NOTICES When Government drawings, specifications, or other data are used for any purpose other than in connection with a definitely related Government procurement operation, the United States Government thereby incurs no responsibility nor any obligation whatsoever; and the fact that the Government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other data, is not to be regarded by implication or otherwise as in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use, or sell.any patented invention that may in any way be related thereto. The information furnished herewith is made available for study upon the understanding that the Government's proprietary interests in and relating thereto shall not be impaired. It is desired that the Judge Advocate (-WCJ), Wright Air Development Center, Wright-Patterson Air Force Base, Ohio, be promptly notified of any apparent conflict between the Government's proprietary interests and those of others. xTY o0 ~~5,X~IY Op 3` ~ P0

WADC TECHNICAL REPORT 57-150 EFFECT OF PRIOR CREEP ON MECHANICAL PROPERTIES OF AIRCRAFT STRUCTURAL METALS Jeremy V, Gluck Howard R. Voorhees James W, Freeman Engineering Research Institute The University of Michigan January 1957 Materials Laboratory Contract No. AF 33(616)-3368 Project No. 7360 Wrig Air Deyel^rnevnt CQenter Air Research'asind- CeveTlopment C oand United,'St'es.,Air Force Wright-Patter^rbn Air Foro.t, 3Ba&ea Ohio

FOREWORD This report was prepared by the Engineering Research Institute of the University of Michigan under USAF Contract No. AF33(616)-3368. The contract was initiated under Task No. 73605, with Mr. E. L. Home acting as project engineer for the Materials Laboratory, Wright Air Development Center. The research is identified as Project No. 2498 in records of the Engineering Research Institute. This report covers work done from February 10, 1956 to January 9, 1957. WADC TR 57-150

ABSTRACT Tests have been performed on two typical aircraft structural sheet alloys in an investigation to study changes in mechanical properties brought about by prior exposure to elevated-temperature creep conditions. Specimens of 2024T86 aluminum alloy and 17-7PH (TH 1050) precipitation hardening stainless steel were exposed for times of 10, 50, and 100 hours at stresses giving up to 3% total deformation, using temperatures of from 350' to 500*F for the 2024T86 and 600' to 900F for the 17-7PH. Following the exposures, short-time tensile, compression, or tensionimpact tests were run at either room temperature, the temperature of exposure, or both. The results indicate that the short-time strength of structural materials may be either raised or lowered. The changes in properties may approach as much as 50 percent of the original value. The direction of the change depends on the material, test temperature, creep exposure conditions, and property being measured. From the standpoint of the structures designer the most important changes found to date are a large drop in strength for 2024-T86 after prior creep exposure for times of from 10 to 100 hours and an apparent decline in the room temperature ductility of 17-7PH (TH 1050 condition) after prior creep exposure for 100 hours at temperatures near 600'F. PUBLICATION REVIEW This report has been reviewed and is approved FOR THE COMMANDER: WADC TR 57-150 iii

TABLE OF CONTENTS Page INTRODUCTION............................. 1 TESTING PROGRAM..2 TEST MATERIALS................ 4 Armco 17-7PH Stainless Steel. *,............. 4 2024-T86 Aluminum Alloy,............... 5 C-110M Titanium Alloy.............. 5 SPECIMEN PREPARATION................. 6 TEST EQUIPMENT.................. 8 Exposure-Test Equipment.............. 8 Tensile and Compression Test Equipment.... *.*... 8 Compression Test Fixture,..,........... 9 Extensometer for Tension and Compression Tests.....,. 9 Tension-Impact Test Equipment.......,...... 10 TEST PROCEDURES....................... 14 Creep-Exposure Test Procedure........ 14 Tension and Compression Tests.. O.D....... d, 15 Tension-Impact Test Procedure.......... 16 Calculation of Effective Gage Length for Extension Measurements in Creep Tests............s...... 17 Metallographic Examinations.......... l,.. 19 EXPERIMENTAL RESULTS.......... 21 Preliminary Total Deformation Curves........ 21 Base Properties of Material Before Creep Exposure...... 22 2024-T86........................ 22 17-7PH (TH 1050)............. 24 Tension Properties after Prior Creep Exposure....... 25 2024-T86................... 26 17-7PH (TH 1050).......s s...... 29 Compression Properties after Prior Creep Exposure..... 31 Tension-Impact Strength after Prior Creep Exposure.......32 Metallographic Examinations,, *......,32 Effect of Re-Machining on Tensile Test Results...... 33 DISCUSSION........................ 35 CONCLUSIONS....................... 36 BIBLIOGRAPHY......................... 37 WADC TR 57-150 iv

LIST OF TABLES Table Page 1. Example Calculation of Effective Gage Lengths for Strip Specimens 17-7PH Alloy (TH 1050 Condition).................... 38 2. Rupture and Total Deformation Data 17-7PH Alloy (TH 1050 Condition).. 39 3. Rupture and Total Deformation Data 2024-T86 Aluminum Alloy..... 40 4. Tensile Test Data for 2024-T86 Alloy..................... 41 5. Compression Test Data for 2024-T86 Alloy.*............ *. 42 6. Smooth-Bar Tension-Impact Test Data for 2024-T86 Alloy........ 43 7. Notched-Bar Tension-Impact Data for 2024-T86 Alloy........ 44 8. Room-Temperature Tensile Data for 17-7PH Alloy (TH 1050 Condition). 45 9. Tensile Test Data at 600F for 17-7PH (TH 1050 Condition)....... 46 10. Room Temperature Compression Test Data 17-7PH Alloy (TH 1050 Condition)...............*.. 47 11. Room-Temperature Tension-Impact Data 17-7PH Alloy (TH 1050 Condition)............... 48 12. Comparison of Tensile and Compression Properties Determined at the University of Michigan or Elsewhere for 17-7PH Given the TH 1050 Treatment................*. 4 13. Effect of Unstressed Exposure on Room-Temperature Tensile Properties of 2024-T86 Alloy........... e *a................ a e e le 50 14. Effect of Unstressed Exposure on Elevated-Temperature Tensile Properties of 2024-T86 Alloy........................... 51 15. Effect of Prior Creep-Exposure on Tensile Properties and Hardness of 2024-T86 Alloy............................ 52 16. Effect of Stressed and Unstressed Exposure on Room-Temperature Tensile Properties of 17-7PH Alloy in the TH 1050 Condition.......... 55 17. Tensile and Yield Strengths of 2024-T86 after Specified Exposure, Expressed as Percentage of Unexposed Value at Test Temperature..... 56 18. Effect of Unstressed Exposure on Room-Temperature Compression Properties of 2024-T86 Alloy.............................. 57 WADC TR 57-150 v

LIST OF TABLES (continued) Table Page 19. Effect of Unstressed Exposure on Elevated-Temperature Compression Properties of 2024-T86 Alloy.................... 58 20* Effect of Prior Creep Exposure on Compression Properties of 2024-T86 Alloy.. * * * *.................... 59 21. Compression Yield Strength of 2024-T86 after Specified Exposure Expressed as Percentage of Unexposed Value at Test Temperature......... 60 22. Effect of Unstressed Exposure on Room-Temperature Tension-Impact Properties of 2024-T86 Alloy......................... 61 23. Effect of Unstressed Exposure on Elevated-Temperature Tension-Impact Properties of 2024-T86 Alloy................... 62 24. Effect of Prior Creep-Exposure on Room-Temperature Tension-Impact Strength of 2024-T86................................ 63 WADC TR 57-150 vi

LIST OF ILLUSTRATIONS Figure Page 1. Sampling Procedure for Sheets of 2024-T86 Aluminum Alloy..... 64 2. Panel Sampling Scheme for Sheets of 17-7PH Stainless Steel Sheet... 65 3. Specimen Blank Sampling Schemes for Panels of 17-7PH Stainless Steel Sheet................... 66 4. Details of Test Specimens.........*............. * * 67 5. Design of Notched Tension-Impact Specimen............. 68 6. Simplified Drawing of Modified Martens Extensometer System Used for Deformation Measurement in Creep Tests.,........ * 69 7. Components of Compression Fixture................. 70 8. Compression Fixture Assembled for Testing with Averaging Extensometer in Place........................ *. *. * 71 9. Original Rod and Tube Extensometer Fixture with O. S. Peters Microformer Strain Follower Attached............. 72 10. Detail of Lower End of Revised Extensometer System......... 73 11. Tension-Impact Specimen and Gripping Assembly for Smooth Specimens.. 74 12. Geometry of Olsen Impact Machine as Modified for Tension-Impact Testing...........................* 75 13. Gage Section of Typical Strip Specimen for Illustration of Calculation of Effective Gage Length *.................. 76 14. Stress Versus Relative Creep Rate at 600, 800, 900F for 17-7PH Alloy in TH 1050 Condition................. 77 15. Time for Rupture and Specified Total Deformations Versus Stress for 17-7PH Alloy in TH 1050 Condition.................. 78 16. Stress Versus Time for Rupture and Specified Total Deformations for 2024-T86 Aluminum Alloy at 350*, 400, 500'F....... 79 17. Comparison of University of Michigan Data Points with Rupture and Total Deformation Curves of Hanlon, Et Al for 17-7PH at 800'F... 80 18. Effect of Temperature on Short-Time Properties of As-Received 2024-T86 Aluminum Alloy...................... 81 WADC TR 57-150 vii

LIST OF ILLUSTRATIONS (continued) Figure Page 19. Representative Tensile Test Stress-Strain Curves for As Received 2024-T86........................ 82 20. Representative Compression Test Stress-Strain Curves for As Received 2024-T86... *.....,, 83 21. Representative Stress-Strain Curves in Tension at Room Temperature for 2024-T86 Alloy after Exposure to Various Amounts of Prior Creep at 350~, 400~, or 500~F....................... 84 22. Representative Stress-Strain Curves in Tension at 350', 400', or 500F after Prior Exposure to Various Amounts of Creep at the Same Temperature....,, o,............. 85 23. Effect of Prior Unstressed Exposures of 2024-T86 on Tensile Properties at Room Temperature and at the Temperature of Exposure....... 86 24. Room-Temperature Tensile Strength of 2024-T86 Alloy after Prior Creep at 350, 400, or 500~F..0............... 87 25. Room-Temperature Tension Yield Strength of 2024-T86 Alloy after Prior Creep at 350e, 400~, or 500'F............... 88 26, Tensile Strength and Tension Yield Strength of 2024-T86 Alloy at Exposure Temperature after Prior Creep for 10, 50, or 100 Hours at 350~, 400, or 500~F........................ 89 27. Effect of Prior Creep Deformation for 10, 50, or 100 Hours at 350, 400~, or 500'F on the Rockwell "B" Hardness of 2024-T86 Aluminum Alloy............................ 90 28. Elongation of 2024-T86 in Tensile Tests at Room Temperature and at 350'F after Prior Creep at 350~F for 10, 50, or 100 Hours....... 91 29. Effect of Unstressed Exposure at Indicated Conditions on Tensile Strength, Elongation, and Hardness of 17-7PH Alloy in TH 1050 Condition............................. 92 30. Stress for 2% Total Deformation in Various Time Periods Versus Test Temperature for 17-7PH Alloy (TH 1050 Condition).......... 93 31. Effects of 100 Hours Unstressed Exposure or 100 Hours Stressed Exposure to 2% Total Deformation at Indicated Temperatures on Room Temperature Tensile Properties of 17-7PH Alloy (TH 1050 Condition).. 94 32. Proportion of Total Loading Deformation or Plastic Loading Deformation to Total Deformation for 17-7PH (TH 1050) Stressed to 2% Nominal Total Deformation in 100 Hours at Indicated Temperature.......... 95 WADC TR 57-150 viii

LIST OF ILLUSTRATIONS (continued) Figure Page 33. Representative Stress-Strain Curves in Compression at Room Temperature for 2024-T86 Alloy after Exposure to Various Amounts of Prior Creep at 350, 400, or 500'F................... 96 34. Representative on Stress-Strain Curves in Compression at 350', 400*, or 500eF after Prior Exposure to Various Amounts of Creep at the Same Temperature....................... 97 35. Effect of Unstressed Exposure on Room-Temperature Compression Yield Strength (0.2% offset) of 2024-T86 Alloy........... 98 36. Effect of Unstressed Exposure on Elevated Temperature Compression Yield Strength (0.2% offset) of 2024-T86 Alloy............. 99 37. Compression Yield Strength of 2024-T86 Alloy at Room Temperature after Prior Creep for 10, 50, or 100 Hours at 350, 400~, or 500F. 100 38. Compression Yield Strength of 2024-T86 Alloy at Exposure Temperature after Prior Creep for 10, 50, or 100 Hours at 350', 400', or 500"F.. 101 39. Effect of Unstressed Exposure on Tension-Impact Strength of 2024-T86 Alloy............................. 102 40. Room-Temperature Tension-Impact Strength of 2024-T86 after Prior Creep Exposure at 350-, 400', or 500~F..............*** * 103 41. Representative Photomicrographs of the 2024-T86 Alloy........ 104 42. Representative Photomicrographs of the 17-7PH Alloy..... 105 43. Effect of Exposure Temperature and Stress on Subsequent Room-Temperature and Elevated-Temperature Tensile Strengths of 2024-T86 Aluminum Alloy Subjected to 10 or 100 Hours of Prior Creep Exposure. *..... 106 WADC TR 57-150 ix

a.) INTRODUCTION This investigation under Contract AF 33(616)-3368 seeks to determine effects of elevated-temperature creep exposure on short-time mechanical properties of several aircraft sheet materials. Test conditions were chosen to produce property changes approximating those which might be induced in airframes subjected to aerodynamic heating. In this initial phase of the study, creep stresses giving up to 3% total deformation in times from 10 to 100 hours have been considered. The properties to be measured before and after such creep exposure are tension, compression and tension-impact properties, together with hardness levels. The current testing program includes sheet materials representative of three types of alloys employed in skins of current air vehicles -- an aluminum alloy, a heat-treatable stainless steel and a titanium alloy. a.) Manuscript released by the authors on 20 February 1957 for publication as a WADC Technical Report. WADC TR 57-150 1

TESTING PROGRAM Materials and temperature ranges to be considered during the first year of the contract were specified as follows: 1. An aluminum alloy, 2024-T86, from 350~ to 500~F. 2. A titanium alloy, C110M, from 6500 to 800~F. 3. A precipitation hardening stainless steel, 17-7PH (TH 1050 condition) from 600~ to 9000F. For the implementation of this program three primary test temperatures were selected to cover the range for each material: 2024-T86 350~, 400~, 500'F C11OM 650~, 700~, 800~F 17-7PH 600~, 800', 900~F Time periods for exposure were fixed at 10, 50, and 100 hours with the exposures to be carried out at zero stress and at those stresses resulting in 0. 5, 1. 0, 2. 0, and 3. 0 percent total deformation in the three time intervals listed. These total deformations include all deformation (both elastic and shorttime plastic strain) occurring during load application plus the creep deformation of the specimen at the creep-exposure temperature and stress. Only three of the variables time, stress, temperature and total deformation can be chosen independently. For ease of scheduling, the first three of these were fixed. The creep-exposure stresses were determined from average curves of log stress versus log time for a given total deformation. The inherent scatter in creep properties results in actual deformations for some specimens greater or less than the desired nominal value. After the exposure period, the following tests were carried out: 1. Tensile tests including stress-strain curves at room temperature and at the exposure temperature. 2. Compression stress-strain tests at the same temperatures. 3. Tension-impact tests at the same temperatures. 4. Hardness determinations at room temperature. Where deemed useful, metallographic examination was made. For a number of creep-exposure conditions, duplicate tests were run with specimens taken randomly from the test material. Properties of specimens with prior exposure to creep conditions were compared with average properties established for unexposed material by a series of from five to ten replicate tests designed to define the normal scatter for each material. WADC TR 57-150 2

The aluminum and titanium alloys were specified to be tested in the conditions supplied by the manufacturers. The C11OM titanium alloy was furnished hot rolled and annealed, and the 2024-T86 aluminum alloy was furnished in the cold worked and artificially aged condition. The stainless steel, 17-7PH was tested in the TH 1050 condition, a double aging treatment which was performed at the University. The aluminum and the stainless steel alloys were specified to be tested in the direction crosswise to the sheet rolling direction, while the titanium alloy was to be tested in the direction parallel to the rolling direction. Initial testing priority was given the aluminum alloy, with no work planned on the titanium alloy for the first year beyond procurement of the material. Work with the stainless steel for the initial contract year has been limited to a survey of effects on room temperature tensile properties from prior creep to 2% total deformation in 100 hours. Temperature increments of 50'F between 600' and 900'F were used with this alloy in order to establish the temperature of maximum effect from creep exposure. WADC TR 57-150 3

TEST MATERIALS The test materials specified by the Materials Laboratory, WADC, were 2024-T86 aluminum alloy, C-110M titanium alloy, and 17-7PH stainless steel. The source, form, analysis, and available processing details for each material are summarized in the sections that follow. Armco 17-7PH Stainless Steel Sixteen sheets of the 17-7PH precipitation hardening stainless steel were received from the Armco Steel Corporation. The material was supplied in sheets 0. 064-inches thick by 36 inches by 120 inches in No. 2D finish and in Condition A. (Condition A consists of an annealing treatment carried out at 1925~F followed by air cooling). The certified chemical analysis furnished by the producer was within the nominal composition limits for this alloy. These are the following: Element Nominal (percent) Actual (Heat 55651) Carbon 0.09 Max 0.072 Manganese 1.00 Max 0.55 Phosphorus 0.04 Max 0.018 Sulfur 0.03 Max 0.011 Silicon 1.00 Max 0.33 Chromium 16.00-18.00 17.03 Nickel 6.50- 7.75 7.25 Aluminum 0.75- 1.50 1.28 Iron Balance Balance The TH 1050 condition was carried out at the University using the following treatment on bundles of one-inch wide specimen blanks. 1. Condition A material heated in air for 1-1/2 hours at 1400+10F, 2. Air cool 10 minutes to approximately 500-F, 3. Quench in 60~F water, 4. Hold 8-12 hours at 60~F, 5. Age 1-1/2 hours at 1050+10~F, then air cool. This treatment is a refinement of that specified by Armco. (See Ref. 1) It was adopted to insure a closer degree of control and uniformity than required by the usual commercial treatment specifications. The 8-12 hours holding at 60~F before the final aging treatment was largely for convenience in scheduling the use of available furnaces. WADC TR 57-150 4

2024-T86 Aluminum Alloy Nineteen Alclad sheets of the aluminum alloy, 2024-T86, were procured from the Kaiser Aluminum and Chemical Corporation. The sheet dimensions were 0. 065-inches thick by 48 inches wide by 72 inches long. Although the heat number of the material was not specified, a certified inspection report was received from the producer stating that the composition of the material shipped to the University was within the following nominal limits for this material: Element Range (percent) Copper 3.8-4.9 Manganese 0.3 -0. 9 Magnesium 1.2-1.8 Silicon 0.50 Max Iron 0. 50 Max Chromium 0.25 Max Zinc 0. 10 Max Others 0. 15 Max Aluminum Balance The T86 condition of this material is a cold working and aging treatment carried out by the producer. It consists of the following steps: 1. Solution treatment: 910-930~F, quench in cold water. 2. Cold work: approximately 5. 5 percent reduction. 3. Aged: 370-380-F, 10 hours. C-11OM Titanium Alloy Eleven sheets of annealed C-110M titanium alloy were purchased from the Rem-Cru Titanium Corporation. The sheets were 0. 064 inches thick by 30-36 inches wide by 60-90 inches long. The material was all from Heat Number A1172600. The chemical analysis furnished by the producer follows: Element Percent (by weight) Manganese 7.9 Carbon 0.10 Nitrogen 0.02 Hydrogen 0. 0093 Titanium Balance WADC TR 57-150 5

SPECIMEN PREPARATION The preparation of test specimens for this investigation involved two considerations. First was the sampling of the specimen blanks from the sheets; and second, the actual design and machining of the specimens. The sampling procedure is very important. A reliable set of base properties (or a scatter band of properties) was essential to provide a base from which any possible changes could be measured. It was also important that the exposure samples be representative of the test stock. In material produced according to given specifications, and especially in sheet material, a number of possible sources of scatter in properties exist. For instance, variations in mill practice and in chemical analysis might result in property differences. Even in material from a single heat, differences in properties from sheet to sheet may arise from inherent variations in processing conditions and, for that matter, inhomogeneities might be encountered over a single sheet. Such variations could result from point-to-point differences in the amount of reduction, segregation carried through from the ingot, or the effects of differing thermal history. Any or all of these sources of scatter could be encountered in the testing of sheet material and must be allowed for when establishing the normal scatter in properties. In the present investigation, it was not deemedfeasible to include possible heat-to-heat variations, wherefore all test material for each alloy was taken from a single heat. However, it was felt essential that variations between sheets and within a given sheet be recognized. Since the physical dimensions of the as-received sheets differed for the several alloys, actual details of the sampling schemes differed although the principle of selection was the same. A prime consideration was that any given test specimen be readily identified according to location. Since both the 2024-T86 and the 17-7PH alloy were specified to be tested in the direction crosswise to the rolling direction, specimens had to be taken across the narrow direction of the as-received sheets in such a way that some idea be gained of the variation in properties across the width of the sheet. This was accomplished by setting up a basic sampling unit termed a panel. Within each panel, specimen blanks were arranged in a non-repeating pattern which represented sampling across the width of the sheet. Repetitions of the panel carried the sampling over the length of the sheet. Three sheets of material were arbitrarily selected for tests of each alloy. Each sheet was sheared into panels five or six inches wide, and the panels themselves sheared into one-inch wide specimen blanks. Figure 1 indicates the sampling scheme for the 2024-T86 aluminum alloy while Figures 2 and 3 show the scheme for the 17-7PH stainless steel. The specimennumbering scheme is also indicated in these figures. Thus, the code number for each specimen identifies its sheet number, panel number, and specimen position within the panel, WADC TR 57-150 6

Dimensions of the various test specimens that were machined from the one-inch wide specimen blanks are shown in Figures 4 and 5. All specimens for the tests of the mechanical properties were designed so that they could be machined from the creep specimens following the desired exposure. For the exposure tests themselves, the width of the gage section of the specimen was machined 0. 030 inches over the 0. 5 inch nominal width for tensile test specimens. The gage section of all types of specimens was remachined after the prior exposure, even under zero load. This common procedure for all tests permits measurement of the properties of the sheet material itself unaffected by the particular edge effects, if any, associated with the prior exposure of a given specimen. For ease in machining, jigs were constructed so that five or six specimens could be made at the same time. The specimens were milled to rough dimensions. The shoulder radii and gage sections were then ground to finished dimensions. The notched tension-impact specimen was prepared to the major dimensions using standard procedures. Following this, a flat-bottomed Vgroove was ground into each edge of the specimen. During this operation the specimen was held in a special fixture so that the location of the notches could be accurately controlled. Next, the center of each flat was nicked with a sharp grinding wheel. Finally, the nicked flat was lapped to the final width and root radius, using a lapping compound and a phosphor bronze wire whose radius was slightly under the final radius desired for the notch. For the notch prepared to the dimensions indicated in Figure 5 the theoretical stress concentration factor, Kt, is equal to 4.2. The notched tension-impact test was added to the program after the dimensions for un-notched specimens had been established. The notch geometry adopted was that which had been previously chosen for notched-specimen rupture tests in another research program being conducted for the Materials Laboratory, The width was thus not the same for smooth and notched specimens used in the present program. This fact should be of little consequence since the desired comparison is not between different types of specimens, but between like specimens with different histories of prior creep exposure. WADC TR 57-150 7

TEST EQUIPMENT The test equipment utilized in this investigation may be divided into two categories: the creep-rupture equipment used to produce the desired exposures either with or without stress; and the equipment for the subsequent tensile, compression, or tension-impact tests. Exposure-Test Equipment The creep-rupture tests and elevated-temperature exposure tests, either stressed or unstressed, were carried out in individual University of Michigan creep-testing machines. In these units the stress is applied to the specimen through a third class lever system having a lever arm ratio of about 10 to 1. The specimen is held by a gripping system that includes universal joints at either end in order to provide uni-axial loading. The specimen is heated by a wire-wound resistance furnace fitting over the specimen ass embly. Strain measurements are accomplished by a modified Martens optical extensometer system. A simplified drawing of this system is presented in Figure 6. Pairs of extensometer bars are normally attached to collars which are pinned through holes in the shoulder sections of the test specimen. This method of extensometer attachment necessitates the use of correction factors in order to obtain the true deformation of the gage section of the specimen, as will be discussed in the section on test procedures. The extensometer bars extend from the bottom of the furnace and are spring clamped (over a cylindrical pin) against machined flats on the bottom specimen holder. Sandwiched between the sets of extensometer bars are the stems of small mirrors. Differential movement of the top and bottom sets of bars causes the mirrors to rotate. A fixed illuminated scale and a telescope fitted with cross hairs are mounted about five feet from the mirrors. As the specimen elongates, a very small movement of the extensometer bars results in a large change in the reflected scale reading observed through the telescope. The factor for converting the observed movement to absolute deformation has been computed from the geometry of the system and checked experimentally. The dimensions of the system used at the University of Michigan permit detection bf a specimen elongation of about 10 millionths of an inch. Tensile and Compression Test Equipment The tensile and compression tests were carried out in a BaldwinSouthwark hydraulic tensile machine equipped with a strain pacer. The holders for the tensile tests were the same type as used for creep testing, while a special fixture discussed in the next section was constructed for the compression tests. WADC TR 57-150 8

For elevated-temperature tests a wire-wound resistance furnace was constructed with a 5-inch diameter core. This larger-than-usual core was necessary to accommodate the extensometer assembly and compression fixture. The difficulties in obtaining temperature distribution over the specimen gage length in such a furnace with a high ratio of core diameter to length were minimized by providing a closer spacing of furnace windings at the bottom of the furnace. Compression Test Fixture The basic design of the compression test fixture was adapted from that of Flanigan, et. al. (Ref. 2). It consisted of a base, a pair of adjustable guide blocks, a loading ram, and a cylindrical head to position the loading ram. The components of the fixture are shown in Figure 7, while the unit is shown in Figure 8 assembled for testing. The base and guide blocks were made from H-40 steel and the loading ram from 17-22A(V) steel hardened to Rockwell "C" 40. The purpose of the guide blocks is to constrain the specimen from lateral buckling during the test. A pair of set screws provides the means for adjustment of the movable guide block. The original guide blocks were smooth surfaced. However, during the initial tests of this unit, to obtain reproducible stress-strain curves with respect to both slope and proportional limit was found to be too much of an art. The receipt of a report (Ref. 3) from the Titanium Metallurgical Laboratory at Batelle Memorial Institute on compression testing techniques led to modification of the compression guide blocks. The results of Kotchanik, et. al., were cited to show that values of compressive modulus (slope of the stress strain curve) were independent of supporting force when the guide blocks contained off-set grooves. Accordingly, a set of grooves off-set from each other were machined into the surface of the guide blocks. These can be seen in Figure 7. This modification of the basic design proved to be successful as judged by the good consistency of data obtained with the modified unit. Extensometer for Tension and Compression Tests Although the Martens extensometer system could have been used for tensile and compression tests, it was not convenient for such short-time tests inasmuch as the measurement of elongation with this system requires alternate readings from the two mirrors and requires periodic interruption for resetting of the mirrors when large strains are involved. Consequently, the tensile machine was equipped with an 0. S. Peters automatic stress-strain recording system to permit a continuous plot of the test results. This recording system also included a strain pacer which permitted accurate control of strain rates. WADC TR 57-150 9

The 0. S. Peters recording system employs a linear variable transformer (or microformer) to detett deformations. To permit the use of the microformer for elevated temperature testing, an auxiliary extensometer unit was constructed to transfer specimen motion outside the furnace. In the original design (See Fig. 9) the extension was transmitted from only one side of the specimen and was sensitive to whether the sides of the specimens were parallel and to the axiality of load application. After initial experience with this equipment, the desirability of an averaging-type extensometer was recognized and the system accordingly modified. The modified system transmits the deformation of the specimen through an averaging linkage. The revised system is shown in Figure 8 set up for a compression test. The specimen is gripped by screws made of heat-resistant alloy and tipped with tungsten carbide inserts. Motion of these screws is transmitted by pairs of flat extensometer bars made of 17-7PH alloy. At the lower ends of these bars are two cross pieces —one attached to a rod and the other containing a tube. The ends of the cross pieces are grooved to fit pins brazed to the lower ends of the extensometer bars. This joint acts in much the same manner as a knife edge. A spring maintains the seat of the pin in the cross piece. Finally, the microformer pickup is attached to the rod and tube. (See Fig. 10) Also essential to this system is the open frame that forms the base for the compression test set-up and which is drilled and tapped at each end so that it can be included in the specimen gripping assembly for tensile tests. The purpose of this frame is to permit the attachment of the microformer to the rod and tube on the center line of the compression or tension axis. This system has been successfully used for obtaining stress-strain curves at room temperature and at elevated temperature in both tension and compression. The extensometer was checked by comparing stress-strain curves obtained with it at room temperature against those in which the microformer was attached directly to the specimen. The results showed excellent agreement, Tension-Impact Test Equipment An existing Olsen impact testing machine was modified to permit carrying out tension-impact tests on sheet specimens. The modifications included construction of pairs of specimen-holding jaws that could be attached to the pendulum of the impact machine, and extension of the striking surfaces so that the impact occurred at the maximum downward point of the pendulum swing. In addition, it was necessary to re-calibrate the scale of the machine to obtain true values of impact strength under the test conditions employed. The design of the specimen-holding jaws is shown in Figure 11 and a schematic representation of the test set-up is shown in Figure 12. WADC TR 57-150 10

The specimen-holding jaws were modified from the design of Muhlenbruch (Ref. 4). The grip assembly was made to screw into a holding assembly fixed to the pendulum head. The specimen itself is held in the split grip sections. A cavity was machined into one side of the split grip to accommodate the specimen. The other half of the split grip has a plane surface and is fixed into position by an indexing pin located at the back end of the grip. The two halves of each grip are locked together by a snap ring. Stiffening rods fixed to the front holder and allowed to "float" in holes in the rear holder reduce the bending tendency of the assembly as the pendulum falls. The striker, which is screwed onto the rear holder provides the necessary tension impact loading as it hits the striking plates of the machine. Since the shoulder dimensions of the notched specimens were different from those of the smooth specimens a set of jaws was constructed for each type of test. Because of the location of the specimen holding assembly, an auxiliary set of striking surfaces had to be added to the existing impact machine base. This modification is indicated in Figure 12. The location of the striking plates was fixed such that the distance L on Figure 12 was the same for the pendulum head and the striking surface in relation to the center of rotation of the pendulum arm. This arrangement permitted the impact blow to take place at the maximum downward point of the pendulum swing. The impact data can not be read directly from the scale of the machine because of the added weight of the grips and because the rear portion of the grips falls from the head immediately after the impact blow. The scale of the machine can be used, however, in the sense that it indicates the height to which the pendulum rises on the up-swing. An arm concentric with the pendulum arm and one-fifth of its lengthcontacts a sine-curve rectifier that slides on a pair of vertical rods. The rectifier in turn contacts an indicating disk which provides a reference point on the scale of the machine. The height to which the indicating disk is pushed above its rest position is directly proportional to the height of the pendulum head. A measurement of the scale showed that 0. 73 inches corresponded to 20 scale divisions. It was then possible to obtain an expression that would convert scale divisions to pendulum height, since a 5:1 ratio exists between the lengths of the pendulum arm and the indicator arm. The expression follows: H' = (0.73)(5) =(0. 0152)(S) 20 (az) where H' is the pendulum height in feet after impact, and S is the number of scale divisions traversed by the indicating disk. Using the terms indicated on Figure 12, the kinetic energy just before impact is Ep = WH - aF WADC TR 57-150 11

where E = initial energy, ft-lb; H - initial height of pendulum center of gravity, ft; W = pendulum weight, lb; a = angle of rotation on downswing, degrees; F = friction loss per degree and the final energy just after impact is Ef = WH' + PF where Ef = final energy, ft-lb H' = final pendulum height, ft P = angle of rotation on up-swing, degrees The difference between these terms is I, the energy absorbed by the impact. Thus, I = Ep - Ef = WH - aF - WH' - PF I = W(H - H') - F (a + 3) The calibration of the machine consisted of the determination of the friction loss and the effective initial height of the pendulum head. Because of the irregular shape of the pendulum head it was necessary that the initial height of the center of gravity of the pendulum be calculated from the characteristics of the machine. The basis of the calibration was the fact that when no specimen is fixed onto the pendulum head, there can be no impact energy absorbed. Thus, the difference in heights would represent the friction loss of the machine. The equation then reduced to the following: I = 0 =W(H - H') - F (a + P) W(H - H') = F (a + P) The pendulum was removed from the machine and weighed. This was found to be 57, 5 pounds. The side plates and front specimen holder were found to weigh 5 pounds and the complete specimen holding assembly was found to weigh 7. 7 pounds. Using these various pendulum weights, the assembly was allowed to fall from the initial height and the final height was determined. Weight S (avg) H Angle of Rotation (a + P) W = 57.5 (pendulum only) 117 1.78 ft. 151~ W + 5 = 62. 5 (plus front grips) 122 1.85 153' W + 7.7 = 65.2 (complete assembly) 123.5 1.88 154' The angle of rotation was determined by laying out the various distances on a sheet of paper and measuring with a protractor. This procedure was approximate and possibly an average angle could have been used. WADC TR 57-150 12

From these data, a series of three equations could be written. Since only two unknowns were present it was possible to use the third equation as a check of the accuracy of the determinations. (57. 5)(H - 1.78) = 151'F (62. 5)(H - 1.85) = 153'F (65. 2)(H- 1.88) = 154~F Solving these equations leads to values of F = 0.40 ft-lbs per degree for the friction loss, and the effective initial height H = 2. 82 feet. With these values known, it was then possible to compute the equation for the actual testing conditions of 65. 2 pounds initial pendulum weight and 62. 5 pounds final weight. (This comes about since the rear grips fall from the assembly after impact. ) With the aid of a cord attached to the rear grips it was possible to simulate the operation of the equipment without a specimen being present. Thus, the rear grips were pulled from the assembly at the maximum downward position. In this case HI was found to correspond to 124 scale units. A value of 155' was used for the angle of rotation and the calibrating equation was written as follows: I = 0 = W1H - W2H' - F (a + 3) I = (65.2)(2. 82) - 62.5 (0. G152S) - 0.40 (155) I = 122 - 0.95S (1) where I is the impact energy absorbed in ft-lbs S is the scale difference This equation was then plotted so that the values of impact energy could be read directly for any measured scale difference. For elevated temperature tension-impact tests a wire-wound resistance furnace was mounted horizontally on a table adjacent to the impact machine so that the specimen and its gripping assembly could be heated prior to their attachment to the pendulum head. It was originally intended that the furnace be mounted vertically so that the specimen assembly as attached to the head could be pushed up, locked into place in the furnace, and then released when temperature had been attained. The high thermal conductivity of the aluminum specimens precluded this since a portion of the grips and the pendulum head remained outside the furnace. This relatively large mass of unheated metal acting as a heat sink resulted in a large temperature gradient over the specimen when attempts were made to heat it while attached to the pendulum head. WADC TR 57-150 13

TEST PROCEDURES Except for elevated-temperature tension impact measurements, rather standard test procedures are available for all tests required for this program. Wherever applicable, ASTM Recommended Practices were adhered to. Other testing details followed practices developed through experience at the University of Michigan. Specimen temperatures for all elevated-temperature tests were measured with chromel-alumel thermocouples wired to the gage section. All thermocouple heads were shielded from direct furnace radiation by a wrapping of asbestos cord. In order to limit the holding time at the start of a test, furnaces were preheated within 50'F of the desired final temperature before specimens were placed into them. The temperature distribution over the entire gage section could be brought to within +3~F of the nominal test temperature in a time period of no more than four hours. For the creep-exposure tests, an elapsed time of four hours between placing the specimen in the furnace and application of the load was adopted to provide uniformity of testing procedures. Creep-Exposure Test Procedure For each creep test, three thermocouples were used, one in the center and one at each end of the gage section. The modified Martens extensometer system described previously was used to measure the deformation both during load application and during the ensuing creep period. For the tests run to large total deformations the extensometer mirrors were reset from time to time to prevent their moving beyond the ends of the fixed scale. At the end of the 10, 50, or 100 hour exposure period a final extensometer reading was taken and the power to the furnace turned off. Experience has shown that cooling the specimen with the load in place minimizes property changes of the type associated with creep "recovery. " For the tests carried out under no load, i.e., temperature exposure only, the same general scheme was used. All the steps of a normal creep test were followed with the exception of the loading. The two duplicate specimens for each unstressed exposure were wired together and run in the same unit at the same time. The slight additional thickness of the material had no detectable effect on the temperature distribution within the furnace. In the initial tests to determine time-deformation data of 17-7PH alloy, the extensometer bars were suspended from pins through the specimen shoulders. For later creep exposures the extensometer bars were attached to collars clamped directly onto the specimen gage section. This procedure proved to be satisfactory in tests with up to two percent total deformation. It had been hoped that all exposure tests could be carried out With collars mounted directly on the gage sections, however, this did not prove to be practical in the case of the 2024-T86 alloy. The softness of this material and WADC TR 57-150 14

its clad coating led to the danger of inadvertently notching the specimen while clamping on the collars. In at least one case, premature failure occurred at a collar mounted on the gage section. Tension and Compression Tests The tensile test procedure with respect to temperature level and distribution was the same as that described for creep-exposure with the exception that two thermocouples rather than three were mounted on the gage section of the specimen. This was necessary in order not to interfere with the extensometer assembly mounted on the gage section. With reasonable care it was found possible to attain a temperature distribution of 2-3~F over the gage length of the specimen mounted in the large core diameter furnace used for these tests. At the higher temperatures it occasionally became necessary to shunt a portion of the furnace winding in order to obtain proper temperature distribution. Due to the manner in which the specimen was gripped in the fixture, it was not possible to mount thermocouples directly on the compression specimens. For actual compression tests, the temperature measurements were taken from couples mounted at the base of the cylinder at the upper end of the fixture and the support block at the lower end of the fixture. With suitable shunting of the furnace winding it was possible to obtain a distribution of 3'F over the fixture. The validity of this method of temperature measurement was checked by comparing the readings from the external couples with the readings from a set of three couples that had been spot welded to the edges of a dummy specimen of 17-7PH alloy. The correlation between the dummy and the external couples was good. For the room temperature tension tests the microformer strain follower was mounted directly on the specimen gage section, while at elevated temperatures the extensometer assembly was used in conjunction with the strain follower. In either case a two-inch gage length was used. All tensile tests were run at a strain rate of 0. 005 inches per inch per minute with the aid of the strain pacer. The test data were recorded in the form of a curve of load versus deformation. From this curve were calculated the 0. 2 percent offset yield strength and the slope of the elastic portion (elastic modulus). The maximum load observed from the recorder trace was used to calculate the ultimate tensile strength. Measurements of elongation and reduction of area were made from the fractured specimen. Because of the clearances that existed in the fixture, it was necessary to use a gage length of 1. 7 inches for the compression tests. After accurately setting the gage length with the aid of a jig, the holding screws were tightened until it was certain that the tungsten carbide tips had achieved a tight grip on the specimen, A light coating of Molykote lubricant was applied to the specimen, the entire assembly placed in the opened compression fixture, and the top of the fixture was then set in place and screwed down. WADC TR 57-150 15

According to Kotchanik, et. al. (Ref. 3) compressive yield strength values obtained from this type of fixture have a critical relationship to the supporting force. Consequently, a torque wrench was used to tighten the specimen guide blocks. A force of from 2 to 4 inch-pounds was found to give consistent results. After the fixture was closed, the assembly was set on the pedestal and placed under the cross head of the tensile machine as shown in Figure 8. Finally, the strain follower was attached to the rod and tube of the extensometer and the recording system zeroed. The load was applied at the approximate tensile machine setting that would give a strain rate of 0. 005 inches per inch per minute in a tensile test. (This was necessary since the extensometer system was actually operated in the reverse direction from a tensile test and thus it was not possible to follow the strain pacer dial). The load application was continued until a marked change in slope was observed in the recorder trace. From the trace, the slope of the elastic portion (compressive modulus) and the 0. 2 percent offset yield strength were determined. Tension-Impact Test Procedure Prior to assembling the specimen in the tension-impact test holding grips, measurements were made of the shoulder-to-shoulder distance and the cross sectional area of the specimen gage section. The actual running of the test consisted of screwing the grip assembly to the holder at the back of the pendulum head which had been previously raised to the fixed initial height. The latch holding the specimen was then released and the head allowed to fall between the striking surfaces. The height to which the indicating disc rose after the impact was read from the scale of the machine and this value converted to energy absorbed upon impact by the use of equation (1), page 13. Measurements of specimen elongation and reduction of area after impact were made on a number of specimens. Although these data are reported, significance of reduction of area for sheet specimens is q ues tionable. A considerable amount of difficulty was encountered in running the elevated temperature tension-impact tests on aluminum specimens (the only material on which such tests have been run to date). It had originally been intended that the specimen in its gripping assembly would be heated in a vertical furnace while attached to the pendulum head. When proper temperature had been attained, it was planned to merely raise the furnace out of the way and release the pendulum latch. However, the high thermal conductivity of the aluminum specimen and the large unheated mass of the pendulum head combined to cause a large temperature difference over the length of the specimen gage section. As an expedient, a procedure was adopted in which the specimen and gripping assembly were heated in a separate furnace and then attached to the pendulum head while hot. In this manner a reasonable temperature distribution could be reached over the specimen gage section. WADC TR 57-150 16

A series of trial runs established the amount of time necessary to remove the specimen from the furnace and attach it to the head. It was necessary that this be done while the operator wore asbestos gloves and thus the operation was somewhat clumsy. Next the amount by which the specimen would cool in this time period was determined. In the actual running. of the tests, the specimen assembly was heated to a temperature that much above the nominal test temperature in order that the actual impact would occur at the nominal test temperature. Fairly consistent values of impact energy were obtained after the operator had gained proficiency in the handling of the hot specimen assembly. Improvements in this procedure are to be attempted before extensive tension impact tests are conducted for the balance of the planned program. Calculation of Effective Gage Length for Extension Measurements in Creep Tests,, Many of the creep data taken in this investigation were obtained using extensometers located between collars attached to pin holes on the shanks of the specimens. The deformation recorded included not only the extension in the gage section but also in the fillets and shanks. Consequently, it was necessary to calculate an effective gage length for these specimens that would take into account the deformation of the fillets and shanks. Two different corrections were needed, depending on whether elastic or plastic deformation was being measured. The elastic correction was used for loading deformations or in short time tensile tests where the Martens extensometer was used, while the plastic correction was used for creep periods. No correction was necessary for tests using the automatic recording system since the extensometer attached directly to the gage section. The effective gage length for the elastic case may be calculated from the specimen geometry alone, A sketch of a typical specimen is presented in Figure 13. This drawing defines the various terms used in the calculation of the effective gage length. The measurements made on a typical specimen were the widths at equal increments of distance from the fillet shoulder to the actual gage section. The widths are tabulated in column (b) of Table 1 for distance increments of 0. 050 inches. In the elastic case the strain in any section is inversely proportional to the area, so that the effective gage length for each short interval was simply the interval length multiplied by the ratio of the relative area of that interval to the area in the gage section. For a sheet specimen, the relative areas (column g) were merely the interval widths. The ratio between this width and the gage section width was multiplied by the interval length (column h) and summed to give the total contribution of the fillet. This was doubled to account for both fillets. The equivalent shank length was the total shank length multiplied by the ratio between the gage section width and the shank width. The shank length is the pin-to-pin distance minus the shoulder-toshoulder distance. The effective gage length then was calculated by subtracting WADC TR 57-150 17

the actual fillet lengths from the shoulder-to-shoulder distance and adding the effective lengths of the fillets and shanks. This is indicated in Table 1 and was equal to SS + 0.45" for the particular specimen design under consideration. For a 0. 530-inch wide specimen, the effective gage length for loading was SS + 0.48". For the calculation of the plastic case, it was necessary to have information on the stress-creep rate relationships for the material at the test conditions. This information was obtained from the test data themselves. Examination of the rough time-elongation data showed that the minimum deformation rate for all specimens occurred at about 25 percent of the rupture life. A calculation was made of the minimum creep rate in scale units per hour at the time corresponding to about 25 percent of the rupture life for that particular stress. The case illustrated in Table 1 considers a gage section stress of 110,000 psi for a test on 17-7PH at 800~F. A plot of stress versus creep rate in scale units is presented in Figure 14. From the specimen geometry, the stress was then calculated at each previously measured interval in the fillet. The stresses are tabulated in column (c). The creep rate at 800'F corresponding to each stress was obtained from Figure 14 and recorded in column (d) and finally the average creep rate was calculated for each 0. 050inch interval of fillet length. The effective length for each 0. 050-inch interval was then calculated by multiplying the length by the ratio of the creep at that particular stress to the creep rate in the gage section (i.e., at 110,000 psi). This calculation, indicated in column (f), was then doubled to account for both fillets. The equivalent length of the shank was computed by multiplying the shank length by the ratio of the shank creep rate to the gage section creep rate. The effective gage length for creep at 800~F was then expressed in terms of the shoulder-to-shoulder distance by first subtracting the actual fillet lengths and then adding the calculated effective lengths of the fillets and shanks. The value obtained for 800'F was SS - 0. 905". The values for 600' and 900~F obtained in a similar manner are as follows: EGL600oF = SS - 1.01" EGL900oF = SS - 0. 83" For the 2024-T86 alloy, similar calculations gave the following results: EGL350~ and 400'F s 0. 70" EGL5OOF =SS - 0. 90" It must be emphasized that such effective gage lengths are valid only for the particular material, temperature and specimen geometry considered. WADC TR 57-150 18

Metallographic Examinations Conventional techniques of mounting, grinding, polishing and etching were followed in preparing specimens of the 2024-T86 and 17-7PH alloys for metallographic examination. Initial polishing steps for the 2024-T86 alloy were carried out on a slow rotating wheel (at about 300 rpm) using 180-or 240-mesh silicon carbide paper lubricated with a few drops of oil. Polishing was started first on 400-mesh and then 600-mesh silicon carbide paper —in each case lubricated with oil, The next step consisted of hand polishing on No, 4-0 emery paper which had been lubricated with a few drops of a kerosene-liquid paraffin mixture (one part paraffin to five parts of kerosene). This step was continued until all previous polishing marks had been removed. Then the specimen was washed with benzene or isopropanol. The final polishing was started on a slow (300 rpm) wheel covered with "Broadcloth," using a polishing medium of 5 micron Alumina, The last steps were carried out on a wheel covered with "Microcloth," using a medium of 1 micron Magnesium Oxide to which had been added a small amount of liquid green soap. The specimen was polished first at 300 rpm, then the wheel was stopped and the polishing finished by hand. Care was taken that the hand polishing be carried out with.a circular motion, The polished samples were photographed in the un-etched condition and then etched with Keller's Etch in order to reveal the microstructure. The composition of this reagent follows: HF (conc) 1 part HCL(conc) 1 HNO3(conc) 2.5 H20 95 A sample of the as-produced material was examined using the selective etching technique described by Keller (Ref. 5) in an attempt to identify its constituents. This technique involved the following etches used in successive order: 1 percent HF; 20 percent H2SO4; 25 percent HNO3; and 1 percent NaOH. The differences by which these reagents attack the constituents can be used to identify them. In addition, a phosphoric acid etch (Ref. 6) was also used for identification studies. The technique for metallographic preparation of the 17-7PH alloy was considerably simpler and easier to carry out than was the case with the much softer aluminum alloy. The samples were first mounted in bakelite and then wet ground in order to remove any disturbed metal. The rough polishing steps were carried out successively on 240-, 400-, and 600-mesh silicon carbide paper on a rotating lap. The paper was lubricated with water throughout these steps. Finish polishing was accomplished with acqueous media of Linde "A" and Linde "B" polishing compounds on rotating laps covered with "Microcloth, " The polished samples were then etched with Marble's Reagent or with a special reagent developed at the University of Michigan for the examination of heat-resistant materials. (See Ref. 7) WADC TR 57-150 19

The composition of Marbles' Reagent follows: CuSoj 20 gm conc H C1 100 ml H2-O 100 ml The composition of the special etch developed at the University is the following: No. 4 Etch 29 % CuC12 in H20 36 % Glacial Acetic Acid 23 % HC1 5 % H2S04 7 % HCrO4 WADC TR 57-150 20

EXPERIMENTAL RESULTS Testing priority in this investigation was given to the aluminum alloy, But since the 17-7PH material was received first, studies on that alloy were carried out until receipt of the aluminum. Work completed on the 17-7PH included: (1) preliminary studies of room temperature properties, (2) 600'F tensile tests, (3) definition of elevated temperature rupture and total deformation, (4) a check of the effect of remachining creep specimen prior to tensile testing, (5) studies of the effects of unstressed exposure and exposure to 2 percent total deformation in 100 hours on the room temperature tensile properties. Experimental results for both materials tested to date are arranged together in the following general order: (1.) Preliminary tests to establish creep deformation properties, (2.) Short-time properties of specimens before creep exposure, (3.) Effect of prior creep exposure on (a) tension properties, (b) compression properties, and (c) tension-impact properties. (4.) Results of metallographic examination and special studies. Preliminary Total Deformation Curves Before the required stress levels could be chosen for the actual creep-exposure periods, data had to be obtained on total deformation as a function of stress and time. Creep-rupture tests on the 17-7PH at 600, 800; and 900'F and on the aluminum alloy at 350', 400', and 500F gave the times listed in Tables 2 and 3 for total deformations between 0. 5 and 3%. The tabulated results include rupture times and fracture elongation, which are useful measures of variability of a material. At each temperature good consistency of rupture and elongation was found. Reduction of area values for sheet specimens are difficult to measure and are often considered not worth reporting. They have been included in the present study largely because the reduction of area is the only measure of ductility applicable to the notched tension-impact specimens. Curves of stress versus time for total deformations of 0, 5, 1, 2, and 3% total deformations were established at each of the test temperatures from the data obtained. (See Figs. 15 and 16) At 600F, none of the test stresses used for the 17-7PH alloy was low enough to give less than 0. 5% loading deformation, while at 800' and 900'F results for 0. 5% deformation were obtained only for time periods of a few hours or less. Consequently, additional tests will be required at lower stresses. In order to fit curves to the available time-deformation data it was necessary to allow for breaks in some of the curves. In general, these curves tend to follow the same slopes as the rupture curves at the same temperature, WADC TR 57-150 21

A check of the 17-7PH data was possible by a comparison with the results of Hanlon, Salvaggi, and Guarnieri (Ref. 8) for tests at 800-F. Figure 17 compares the two investigations. The agreement appears to be good. The curves for 0. 5 and 1.0% total deformation were established for the 2024-T86 alloy without too much difficulty at all three temperatures, but 2. 0% appeared to be a practical limit for deformation at 350~ and 400'F. Even this required stresses to within 1000 psi of the rupture strength and examination of Figure 16 reveals the difficulty of stress selection inherent in trying to reach 2.0 and 3.0% deformations in 10, 50, or 100 hours. Therefore, for the time being, the attainment of 3. 0% total deformation was ruled out at 350~ and 400~F. Even at 500~F, stresses selected from Figure 16 to give 3% deformation resulted in fracture before the time period for creep exposure was over, Hardness measurements taken on the 17-7PH (TH 1050) specimens after the completion of testing are included in Table 2. They show a moderate increase in hardness from exposure to time, stress, and temperature. Random hardness impressions taken on each sample, three in the shanks and three in the gage section, show no significant differences in hardness between the shanks and gage section. An analysis of the hardness data indicated that the hardness change at all test temperatures was significant with respect to the as-treated (base) condition, but that there was no significant difference between the average hardness changes for 800~ and 900'F exposures, while the difference between the 600'F exposures and the other two temperatures was on the borderline of significance. Base Properties of Material Before Creep Exposure Sufficient tension, compression and tension-impact tests were conducted on random specimens of the 2024-T86 alloy to establish the normal scatter in properties both at room temperature and at the temperatures used for creep exposures —350~, 400~, and 500~F. Results for the three types of tests are listed separately in Tables 4 through 7. With the 17-7PH stainless steel in the TH 1050 condition, tension tests to establish base properties have been completed only for room temperature and for 600~F. Compression and tension-impact properties were obtained only at room temperature during the first year of the contract. (See Tables 8 through 11) 2024-T86 The results of ten tension tests at room temperature and nine at each of the elevated temperatures (Table 4) shows good agreement in the ultimate and yield strengths for 2024-T86 specimens. Differences between sheets appear to be no greater than the differences within an individual sheet. Statistical analysis of the data indicate that creep exposure must result in a change in strength from the unexposed condition greater than 1500-3000 psi for the change to be significant. WADC TR 57-150 22

At the elevated temperatures, the strengths were lower and the spread between the tensile and yield strengths decreased. Thus, at room temperature the yield strength was about 5, 000 psi lower than the tensile strength, while the spread had decreased to approximately 1,500 psi at the higher temperatures tested. The elongations and reductions of area showed only a moderate increase over the room temperature values for tests up to 500*F. These effects of temperature on properties of the as-received material are brought out by Figure 18. The room temperature compression yield strengths for 2024-T86 show perhaps a bit more scatter than did the tensile yield, however, the elevated temperature values have about the same scatter for both tension and compression. The scatter within sheets appears to be of the same order as the scatter between sheets. The compression yield strength was about 5,000 psi higher than the tensile yield strength at room temperature and about 10, 000 psi higher at the three elevated temperatures, 350~, 400*, and 500*F. Thus, at room temperature the compression yield strength is about 105 percent of the tension yield strengthwhile at 500~F it is of the order of 125 percent of the tension yield strength. Representative stress-strain curves in tension and in compression are shown in Figures 19 and 20. The elastic modulus, as determined from the slope of the initial portion of such curves is about the same for tension and compression in corresponding tests at room temperature or at 350'F. At 400' and 500'F the compression modulus was higher than the value for tension. The average values for the tension-impact data in Tables 6 and 7 have been included on Figure 18. The data for each testing temperature show a large scatter in tension impact strength within individual sheets, but the scatter between the sheet averages is fairly small and the sheet averages agree well with the average value for all tests run at a given temperature. Thus, although the reliability of an individual tension-impact value might be questionable, the average of several tests can be considered a fair measure of the impact properties. Increasing the test temperature appeared to have little effect on the tension-impact strength. The average values showed a slight decrease in strength at 350', an increase at 400', and a decrease at 500 F. No explanation is offered for the hump at 400'F. Since the smooth-bar tests appeared to show little sensitivity for tensionimpact strength with temperature, two notched-bar tests were run at each of the test temperatures. These results, reported in Table 7, are also plotted in Figure 18. The notched-bar strength was almost exactly half the smooth-bar strength, while the effect of test temperature was the same as that for smooth bars —even to the occurrence of the hump at 400'F. Again, no explanation for this behavior is evident. WADC TR 57-150 23

Statistical analysis of the room temperature data for smooth bars indicated that for a change in tension-impact properties to be significant with respect to the as-received condition, a difference of 3 ft-lbs would be necessary, while the significance limit between the averages of pairs of exposed samples would be 4 ft-lbs. 17-7PH (TH 1050) The room temperature tension data of Table 8 indicate that the samples from 17-7PH Sheet No. 1 were somewhat stronger and less ductile than the samples from Sheets 2 and 3. There was little difference between the hardnesses of the samples from all three sheets. The average properties at room temperature were calculated for each sheet and for all tests. Since six specimens were run from Sheet 1 and only two each from Sheets 2 and 3, a second set of averages, that of the average of the sheet averages, was calculated to reduce the bias that would result from the simple average of all ten tests. The basis for this was that an average of the three sheets should not be weighted 60 percent with values from Sheet 1. Statistical analysis of the scatter in the room temperature data indicated that changes in tensile and yield strength after exposure would have to be about 12,000-15,000 psi in order to be significant. The tensile tests at 600'F showed less scatter from sheet to sheet than they did at room temperature; however, large differences in strength were noted within Sheets 2 and 3. In Sheet 2, one of the three samples was quite a bit weaker than the other two, while in Sheet 3 just the opposite was the case, The scatter from low to high in room temperature strength represented about 14 percent of the average strength, while at 600~F the scatter was about 17 percent of the average value. The drop in average tensile strength from room temperature to 600*F was about 15 percent of the room temperature strength. Elongation decreased as the testing temperature increased. Room-temperature compressive yield strength for 17-7PH showed fair consistency. (See Table 10) The scatter between sheets and within individual sheets was slightly greater than the scatter previously encountered in tensile tests of the same material. In addition, the deviation from low to high individual values was about 22 percent of the average strength for all sheets. These results suggested that significant changes in compressive yield strength would be of the order of from 15,000 to 18,000 psi. Both the compression yield strength and modulus were higher than those obtained in tension, with the compression yield about 12-13 percent higher. The increase in modulus for compression over tension was of the order of 4-5 percent. WADC TR 57-150 24

The as-treated tensile and compression properties of 17-7PH determined at the University of Michigan were compared with the results available in the literature from other laboratories. Such a comparison indicates not only the possible heat-to-heat variability of the material, but the effect of heat treatment within the commercial specifications. The data summarized in Table 12 indicate a fair correlation between the results of the various laboratories. While the Cornell values (Ref. 11) of room temperature strength were the highest, they corresponded to the higher hardness reported. The WADC results (Ref. 9) were reported for material of two hardness levels, with the University of Michigan results falling between. The Armour results (Ref. 11) were a bit lower, while the typical values given by Armco were the lowest of all. The 600*F results obtained by the University of Michigan and by Armour were somewhat higher than either the WADC or Armco data. The compression yield strength determined at the University of Michigan was somewhat higher in absolute value than the data from other sources but were about the same percentage higher than the tensile yield strength as were compression results from other laboratories. These data indicate that the material treated at the University of Michigan was fairly representative of the alloy, although the tensile properties were somewhat on the high side. The results of tension-impact tests run at room temperature on both smooth and notched specimens of the 17-7PH alloy are summarized in Table 11. As mentioned in the section on specimen preparation, the notched samples had a theoretical stress concentration factor of 4. 2. The notched-bar tests showed a greater degree of scatter than did the smooth-bar tests. In both cases, however, the average values of impact energy absorbed were lowest for specimens from Sheet 1. In the case of the smooth bars, Sheet 2 was intermediate in strength while Sheet 3 was intermediate in the case of the notched bars. For both types of test it appeared that the scatter between extreme values within an individual sheet was greater than the scatter between the averages of the sheets. Based on the averages of all tests, the effect of the notch was to reduce significantly the amount of energy absorbed upon tension-impact. It should be noted, incidentally, that the cross sectional area at the base of the notch was 25 percent greater than the gage-section area of the smooth samples. Slight and probably unaccountable differences in the notches themselves may have contributed to the scatter in the notched bar results. Tension Properties after Prior Creep Exposure Tables 13 and 14 list results of short-time tension tests at room temperature and at the exposure temperatures for 2024-T86 specimens exposed to 10, 50, and 100 hours at 350*, 400', and 500-F without any applied stress. The added effect of stress to cause total deformations of 0,5, 1, 2, and 3% in the 10, 50, and 100 hour periods of creep exposure was studied in experiments reported in Table 15. On both Tables 13 and 15, hardness data have been included. WADC TR 57-150 25

Effects of both stressed and unstressed exposures at temperatures between 600* and 900*F on room-temperature tensile properties of 17-7PH alloy are covered by the listings in Table 16. In these tables each specimen is described by the nominal exposure conditions, the actual exposure conditions, the actual deformation obtained, and the tensile properties after completion of the exposure treatment. The nominal exposure conditions consisted of the exposure time, temperature, and desired total deformation. The stress to produce this deformation was estimated from the total deformation data of Figure 15 and 16. The actual deformations obtained differed somewhat from the nominally specified deformation, However, every effort was made to cover the range of deformations specified to be studied and the data were correlated with respect to the actual deformation, Measurement of specimen extension both during load application and during the following creep-exposure period permitted separation of the total deformation into its component parts. In many cases the test stresses were below the proportional limit, but in a few cases there was some plastic deformation on loading. The amount of this deformation was quite small. The major portion of the plastic deformation occurring during a test was from creep at the testing temperature and stress. This component, designated the creep deformation, was obtained by subtracting the total loading deformation from the total deformation at the end of the test, The contract called for a study in terms of fixed total deformations, but the total plastic deformation, short-time plastic deformation (from loading), or the creep deformation may prove to offer better general correlations of the final data. For this reason the several components of the total deformation have been included on the tables of data where such entries are appropriate. In several cases, separate curves of results have been plotted in terms of total deformation and of creep deformation. 2024-T86 Representative stress-strain curves in tension have been assembled in Figures 21 and 22 to illustrate in graphical form the general effects of prior creep or of exposure to temperature alone on subsequent yielding of 2024-T86 alloy. Room-temperature yield strength was noticeably reduced by exposure to the elevated temperature, with a greater reduction as the creep-exposure temperature increased from 350' to 400* to 500*F. For the same length of the exposure period, the decline in yield strength brought about by exposure to temperature in the absence of applied stress was greater than the further decline in strength for stresses causing creep to tbtal deformations of 0. 5-3%, especially at the lower two temperatures where the stress-strain curves seemed to be rather independent of the stress at which exposure took place. The fourth set of curves for room temperature stress-strain tests after prior exposure at 400*F illustrates the progressive lowering of yield strength when the exposure time is increased from 10 to 50 to 100 hours. WADC TR 57-150 2 6

Corresponding sets of representative curves in Figure 22 illustrate trends for tension stress-strain characteristics at the exposure temperature after prior periods of creep or of unstressed exposure. In contrast to the findings for room temperature tension tests, prior exposure to the elevated test temperatures under zero stress appeared to have no particular effect on the subsequent yield at 350~, 400~, or 500~F. However, creep due to an applied stress during the exposure period did measureably lower later yield strength at temperature. This lowering of strength was but slightly influenced by the amount of creep which took place. The set of curves for different times of exposure at 400~F at stresses giving about 1 percent of creep deformation suggests that the time of creep exposure may be more important than the amount of creep obtained, at least insofar as later yield strength is concerned. The curves of Figure 23 show graphically the data of Tables 13 and 14 for tensile properties after prior exposure to elevated temperature under zero stress. Unstressed exposures at 350~F for 10 - 100 hours resulted in a slight drop of room-temperature yield or tensile strength. Decrease in room-temperature strength was progressively greater for exposure at 400- and 500~F. For all three temperatures of prior unstressed exposure, declines in room temperature strength were greater for longer exposure periods. The yield and ultimate strengths in tension for tests conducted at the exposure temperature showed no large effect of prior holding at temperature without stress. Subsequent elongation at fracture seemed to be rather independent of the prior unstressed exposures considered for tests at room or elevated temperature. In the room-temperature tests with prior exposure at 500~F, a 20 - 30 percent drop in yield or tensile strength was observed after a 10-hour unstressed exposure. With duplicate tests, the tensile and yield strengths after 50 hours of prior exposure were about the same as for 10 hours, while a longer time exposure (100 hours) resulted in noticeable drop in strength below the values after 10 and 50 hours exposure time. This observed trend could be the result of erratic data, but could also reflect a double-peak aging reaction such as has been reported for this alloy composition (See Ref. 12). The factor of deformation during the creep-exposure period has been added to the test data presented in Figures 24 through 26. In the first two of these figures, room-temperature strength was correlated separately against creep deformation and against total deformation, with the creep-exposure time and temperature as parameters. In all cases the creep deformation was such a predominant part of the total that the character of the curves is the same whether results are plotted against total deformation or against the creep deformation above. Some decrease in tensile and yield strength is suggested with increased amounts of prior deformation at 350'F. It should be recognized that the points for zero deformation indicate that the loss of strength from time at temperature alone was of the same order of magnitude as the effects of creep under stress. The data of Figure 26 show the decrease of strength in tests at 350'F to be about the same as the loss of room-temperature strength after the same amount of prior creep exposure. WADC TR 57-150 27

With prior creep at 400~F, the effect of deformation during the creep exposure on reduction in subsequent strength was greater than for creep at 350eF. The room-temperature strength was further reduced by prior deformation by about the same amount that it was reduced by exposure to temperature alone. A condition that produced 2-percent total deformation in 100 hours at 400~F resulted in a drop in room-temperature tensile strength to 80 percent of the unexposed value and a drop in the 400'F tensile strength to about 75 percent of the unexposed value. The corresponding yield strengths were reduced to 70 and 75 percent respectively of the unexposed value. Exposure to temperature alone for the same time period reduced the room-temperature tensile and yield strengths by 15 and 25 percent respectively, while the strengths at 400eF test temperature (Fig. 26) were virtually unaffected. The data for 500'F prior creep exposure show a severe loss in subsequent tensile strength at both room temperature or 500'F after exposure. The exposure to temperature alone resulted in a loss of about 18 - 22 percent of the roomtemperature tensile strength and from 30 - 45 percent of the room-temperature yield strength, depending on the length of the prior exposure time. The effect of stressed exposure caused a further drop in the subsequent strengths. Onehalf percent total deformation at 500'F dropped the room-temperature strength to about 60 - 70 percent of the unexposed value and cut the yield strength almost in half. Larger amounts of total deformation accentuated the loss of strength. After the most severe condition —- 100 hours exposure to 3 percent total deformation —- the room-temperature tensile strength was 53 percent of the unexposed value and the yield strength only 33 percent of the unexposed value. The strengths at 500~F (shown in Fig. 26) were similarly affected by exposure at 5001F. The unstressed exposure to temperature alone had little effect on the tensile properties —reducing the tensile and yield strengths by only 6 or 7 percent in the extreme case. However, stressed exposure had a severe and immediately deleterious effect on the 500'F strength. In many cases the tensile strength was reduced to 50 - 75 percent of the unexposed value. The yield strengths were reduced about the same percentage as were the tensile strengths. This was contrary to the results of room-temperature tests of the same conditions which showed the yield strength to be reduced a greater percentage than was the tensile strength. The most severe drop in both the room-temperature and elevated-temperature strengths occurred up to 1. 0 percent total deformation. Thereafter the subsequent tensile and yield strengths leveled off. In the case of 10 hours creep exposure at 500-F the room-temperature strength appeared to increase slightly with amounts of prior creep deformation beyond 1.5 - 2. 0 percent total deformation. The relative effects of the various prior creep exposures on tensile strength and yield strength in tension are summarized in Table 17, with the strengths expressed as a percent of the unexposed value for the given test temperature. At 350-F the maximum loss of strength is listed as about 15 percent, at 400eF the loss of strength ranged to 25 percent, while at 500-F a loss of 50 - 60 percent of the original strength was encountered for the longer times and greater amounts of total deformation. WADC TR 57-150 28

Hardness determinations at room temperature run on the exposed specimens were listed in the tabular data referred to earlier. These data for the 2024-T86 alloy have been plotted in Figure 27 as a function of exposure temperature and time. Effects of both unstressed and stressed exposure follow the same general course as was found for tensile and yield strengths. Hardness decreased with both longer exposure times and higher exposure temperature. For prior creep at 500~F, the curve indicated a reversal in slope at 50 hours exposure time. The time of exposure appeared to have little influence on the elongation in tensile tests after prior creep exposure. In general, larger creep deformations at any temperature seemed to reduce the elongation measureably, especially for subsequent tests at the exposure temperature. The curves of Figure 28 for exposure at 350'F demonstrate the type of results obtained. 17-7PH (TH 1050) Table 16 lists all data obtained to date on effects of prior exposure on subsequent short-time properties of 17-7PH. Included in the tabulation are results of room-temperature tensile tests for specimens exposed at zero stress for 10, 50, or 100 hours at 600, 800-, or 900F. Two specimens from different sheets were run at each exposure condition. A plot of the average values of tensile strength, elongation, and hardness versus exposure time is presented in Figure 29. Statistical analysis of the replicate tests of the as-treated material had indicated a change of 12, 000 to 15, 000 psi would have to be obtained in order to be significant. The data indicate that the unstressed exposures at 600'F had no significant effect on the tensile strength of the material. The effects were also negligible for 10 hours exposure at both 800 and 900~F. However, the longer exposures at these temperatures did result in a significant increase in the strength. At 900'F there may have been a maximum effect somewhere between 50 and 100 hours, while at 800'F, there may be a maximum effect at somewhat over 100 hours. The hardness data confirm the trends indicated by the tensile strengths. Elongation shows slight change, although moving consistently in the opposite direction from the change in strength. The scatter in strength between replicate exposure conditions was most pronounced for the exposures carried on at 600' and for 10 hours at 800-F and ranged from 6,000 to 17,000 psi. At longer times and higher temperatures, the two values were only 500 to 4,000 psi apart. By mutual agreement between the University and WADC an initial phase of the evaluation of the 17-7PH alloy was a survey of the effects on the room-temperature tensile properties of creep to two-percent-total deformation in 100 hours. The exposure temperatures were fixed at 50'F increments between 600' and 9000F. The stresses required were interpolated using data from the totaldeformation curves of Figure 15, replotted as shown in Figure 30. WADC TR 57-150 29

At least two tests were run for each condition chosen. Results of this preliminary study are among the data of Table 16. Plots of tensile strength, yield strength, elongation,and hardness (all taken at room temperature) are presented in Figure 31 as a function of exposure temperature. The effects of both stressed or unstressed exposure were to raise the tensile and yield strengths over the as-treated value. Significant effects were noted for unstressed exposures at 800* and 900~F, and for stressed exposures at all temperatures above 600~F. The stressed exposure raised the strength to a greater extent than did the unstressed exposure, with the maximum effect for both occurring at about 850~F. The strengthening effect of stressed exposure over unstressed exposure appears to be greater in the case of the yield strength than for tensile strength. The effects of the exposures on the hardness and elongation were contrary to the trends indicated by the tensile and yield strengths. At the lower end of the range of exposure temperature the elongation was greatly reduced by stressed exposure. At 800'F creep-exposure temperature the elongation of the unstressed samples also showed some reduction; elongations for both types of exposures tended to converge thereafter. The final hardness for samples given stressed exposure tended to be slightly lower than the hardnesses of the unstressed samples, at least up to exposure temperatures of 800~ - 850~F. This was contrary to the normal expectation that increased hardness would accompany the higher tensile and yield strengths of the stressed samples. The most significant results of this initial survey appear to be the following: 1. Stressed or unstressed exposures between 600- and 900*F tend to raise the tensile and yield strengths. 2. The effect of stressed exposure is greater than that for unstressed exposure —particularly in reducing the spread between the tensile and yield strengths. 3. The temperature of maximum effect is about 800 - 850'F. 4. At the lower end of the temperature range, i. e. 600~ - 750*F, stressed exposure greatly reduced the room-temperature ductility. This low room-temperature ductility after stressed exposure at 600~ to 700'F may be the most important effect noted in this survey. Extension of the testing to temperatures below 600'F would appear valuable in order to better define any adverse results from prior creep or time at temperature. Attention is called to the variability of total deformation obtained at 600~F with 17-7PH specimens under substantially identical creep-exposure conditions —despite fairly consistent loading deformation. This behavior is perhaps not too unusual in that this alloy has a rather extensive period of relatively-rapid primary creep early in the test and since primary creep tends to be variable from test to test. WADC TR 57-150 30

The proportion of total deformation which occurred during load application was rather high at 600OF due to the high stresses involved, but most of the loading deformation even in this case represented elastic strain. Figure 32 presents the ratio of loading deformation to total deformation and the proportion of the loading deformation due to the elastic portion. The results indicate that even at 600~F most of the total deformation is due to the creep during the exposure period. Compression Properties after Prior Creep Exposure To date compression tests on exposed material have been completed only for the 2024-T86 aluminum alloy. The results of such exposures in the absence of stress are listed in Tables 18 and 19 respectively for subsequent tests at room temperature and at the exposure temperature. Effects of stress during the exposure period are considered in the tests reported in Table 20. Actual stress-strain curves for representative compression tests have been reproduced in Figures 33 and 34. At room temperature, the same period of exposure at a given temperature seems to have lowered the yield strength about the same degree regardless of the stress present during the exposure period. The greatest factor in strength after exposure appears from these curves to be the temperature of the exposure, with little further influence of the duration of exposure or the deformation during it. Tests at the elevated temperature of the prior creep exposure are similar except that now larger deformations during the exposure period resulted in lower compression yield strengths than did unstressed exposures or low prior creep deformations. Figure 35 summarizes the effect of the exposure conditions on the room temperature compression yield strength (0.2 percent offset strength), while Figure 36 is a similar plot for the compression yield strength at the exposure temperature. The room-temperature results were somewhat similar to the effects of exposure on the tensile strength. Exposures at 350~ and 400'F resulted in a progressive loss of strength with both temperature and time of exposure. At 500oF there was a severe drop in strength for 10 hours exposure and then an increase at 50 hours and an intermediate decrease at 100 hours. Ten hours exposure at 500'F reduced the room-temperature compression yield strength almost 39 percent below the unexposed value, while 50 hours exposure reduced the strength only 24 percent and 100 hours exposure reduced the strength about 29 percent. This behavior is a probable manifestation of the double aging reaction mentioned earlier. Apparently the compression properties were more sensitive to this effect than were the tensile properties. What might be considered more normal behavior was exhibited by the effects of exposure time on the elevated temperature compression yield strength (Figure 36). In this instance, an increase in the exposure time and temperature resulted in a loss of strength throughout the range of time and temperature studied. The first ten hours of exposure had relatively the greatest effect; thereafter the strength dropped off less rapidly with time. A major loss of strength from the unexposed value —53 percent —was observed for 100 hours exposure at 500'F. The loss of strength at 350F was slight, only about 3 percent for 100 hours exposure. One hundred hours exposure reduced the 400~F strength by about 16 percent. WADC TR 57-150 31

Compression yield strengths after prior creep are shown in Figures 37 and 38 for tests at room temperature and at the creep temperature. Separate curves are plotted for exposure periods of 10, 50, and 100 hours, with separate presentations against creep deformation and against total deformation during the exposure period. For exposures at 350~ or 400'F, and for a fixed exposure time, the curve of room-temperature compression yield strength versus creep deformation or total deformation exhibited a peak at intermediate values in the deformation range investigated. In contrast, all curves for 500~F creep exposure and the curves of elevated-temperature strength for 350'F and 400'F exposure exhibited a steady decline from zero prior deformation to the largest deformation used. The explanation for these observations is not immediately apparent. The percentages of the initial compression yield strength retained after specified exposure conditions are listed in Table 21. After 50 - 100 hours creep at 500'F, half or less of the original strength may remain. Tension-Impact Strength after Prior Creep Exposure Tension-impact tests after prior creep-exposure histories were limited to the 2024-T86 alloy. (See Tables 22 through 24 and Figures 39 and 40). From Figure 39, a possible slight drop in room temperature tension-impact strength is indicated with time and temperature of exposure. However, the results of the 100-hour exposure tests are confusing. One hundred hours at 4000 or 500'F apparently raised the tension-impact strength. The scatter between the 100 hour results at 350~F was large, with the average of the two determinations indicating a drop in strength from the 50-hour value at this exposure temperature. It will be remembered that analysis of the replicate tests on the unexposed material indicated that the significant changes in tension-impact strength between pairs of determinations would be about 4 ft-lbs. On this basis, only the 500~F exposures showed a significant change in properties with respect to the unexposed condition. Thus, it appears that the room-temperature smooth-bar tensionimpact test was not as sensitive to the effects of unstressed exposure as were the tensile and compression tests. Absolute effects of prior unstressed exposure on elevated-temperature tension-impact strength were small, possibly less than the limit of significance. Effects of creep during the exposure period prior to tension-impact testing at room temperature appear to be quite variable from the curves plotted in Figure 40. If we disregard the point for 350~F with the largest deformation studied for 100 hours exposure, tension-impact strength at room temperature seems not to be much affected by moderate changes in conditions of prior creep exposure. Metallographic Examinations Samples of 2024-T86 and 17-7PH alloys were studied metallographically to establish a record of the microstructure before testing and to examine for structural changes brought about by the testing. WADC TR 57-150 32

Photomicrographs of the aluminum alloy shown in Figure 41 include the as-received material and specimens after creep exposure at 350- and 500~F, respectively. The latter two samples were chosen to have about the same amount of total deformation from the creep exposure. Apparently, the 500'F exposure altered the response of the material to the etchant, but possible visible precipitation had occurred in this sample. The specimen exposed at 350'F shows evidences of deformation and a variation in the overall grain size. Using selective etching techniques, the following phases were identified: Cu A12; A12 Cu Mg; A17 Cu2 Fe. Others may be present and this list of constituents is not intended to be all-inclusive. An incomplete metallographic examination of the 17-7PH alloy included specimens of the material as received (Condition A) and after the TH 1050 heat treatment. (See Figure 42). The effect of the heat treatment was precipitation both within the grains and at grain boundaries. A creep-test specimen examined after some 500 hours at 800~F and 90,000 psi showed evidence of over-agihg of the precipitate. (See Fig. 42) Effect of Re-Machining on Tensile Test Results In the section on Specimen Preparation it was noted that the design of creep specimens is such that after creep exposure the edges of the gage sections could be remachined before subsequent tests of mechanical properties. This was done for two reasons. First, it was desired that the final tests measure the properties of the sheet material itself and not the particular specimen's edge effects. Second, it was desired that the practice for subsequent tensile test specimens conform to that adopted for the tension-impact and compression specimens which were designed to be machined from the gage section of an exposed creep specimen. The question arose as to what effect, if any, the subsequent remachining operation would have on the tensile properties of an exposed specimen. A check test was run on 17-7PH specimens intended for exposure at 700'F and 120,000 psi to reach 2 percent total deformation in 100 hours. One specimen, 2R-T2, was given the standard remachining operation after exposure. Another specimen 3Q-T6 was given the identical exposure and then tensile tested without remachining; i. e., with 0. 530-inch wide gage section. The results of these tests follow: Ultimate Total Tensile 0.2% offset Deformation Strength Yield Strength Elong. Red. of Area E, Hardness (%) (psi) (psi) %-2 in. (%) 10 pi R"C" R emachined (2R-T2) 2.54 219,000 218,000 2.2 13.7 30.6 44.0 Not Remachined (3Q-T6) 1.95 220,000 219,000 3.5 13. 8 29.6 44.2 WADC TR 57-150 33

The result of these two tests indicates that the remachining operation apparently had no significant effect on the tensile properties. The effect of remachining on the subsequent elevated temperature tensile properties of 2024-T86 given unstressed exposure was also checked for two specimens given 100 hours exposure at 400 or 500~F. Results were checked against two specimens given the identical exposures and then remachined. The data, included in Table 15, show that the tensile strength of the un-machined samples was slightly higher than the remachined samples. However, the yield strength, elongation, and reduction of area showed good agreement with the remachined results. In any case, no cause to depart from the adopted procedure is evidenced. WADC TR 57-150 34

DISCUSSION To date, two results of concern to the designer have been noted to result from prior creep exposure: (1. ) A marked decline in subsequent short-time strength for the 2024-T86 aluminum alloy, (2.) An apparent drop in subsequent ductility of 17-7PH after prior exposure to temperatures around 600'F. The best way to present these findings for possible design application must still be resolved. For structures in which critical sections are subject to local concentrated stresses, the estimated total deformation imposed by the geometry and loading of the structure may be the preferable criterion against which to correlate strength and ductility changes. For most structures subjected to creep during service, only the permanent deformations can be measured. In this case, the strength changes would probably be desired in terms of total plastic deformation (or creep deformations if the initial plastic strains of loading are small). Perhaps the simplest correlation for most general use would be in terms of the temperature and stress present during the period of creep exposure. Figure 43 illustrates a possible graphical presentation of subsequent tensile strength after creep exposures for 10 hours and 100 hours. In this figure the limiting exposure condition, shown in dashed lines, corresponds to the rupture strength for the exposure time and temperature under consideration. These initial findings correspond to a rather limited range of test variables and only one type of prior history —constant-stress creep for exposure periods between 10 and 100 hours. Results obtained may or may not be the same as effects on short-time properties caused by the variable or complex stressing, alternating loads and fluctuating temperatures of actual service. Some data which were obtained indicated the direction of stressing may be important. Thus, the compression properties of the 2024-T86 alloy showed a greater reduction than did tension properties after the same prior creep in tension for the two cases. An operating structure may be subjected to simultaneous stresses acting in different directions. Proper application of the simple-tension data of a study such as this to actual structures is as yet unaswered. Even the two different alloys studied to date show that the direction of strength changes after prior creep varies with the particular material and conditions involved. Until such time as sufficient data are on hand to generalize the trends, test results appear to be needed for each alloy, major heat treatment and range of exposure conditions. WADC TR 57-150 35

CONCLUSIONS Rather complete coverage has been given to 2024-T86 aluminum alloy in a study of effects on short-time mechanical properties from total deformation up to 2% at 350~, 400~, and 500~F, in 10, 50, and 100 hours. Limited data with 17-7PH alloy in the TH 1050 condition have also been determined for creepexposure temperatures from 600~ to 900'F. Test results obtained suggest the following conclusions: 1. Short-time strengths may be either raised or lowered by prior exposure to temperature, with or without the presence of stress. Changes in strength may be as much as 50% of the original value. The direction and magnitude of the changes depends on the material, test temperature, creep-exposure conditions, and the property being measured. 2. Exposure to temperature in the absence of applied stress had approximately the same magnitude of effect on subsequent properties as did the added effect of creep during the exposure period. In most cases, longer exposure times and larger amounts of deformation during the exposure resulted in greater changes in mechanical properties. 3. For the 2024-T86 alloy tests, compression properties showed a greater sensitivity to tension exposure conditions than did tensile properties. Tensionimpact strength was relatively insensitive to prior creep exposure. 4. The most important changes from a designer's standpoint are a large drop in the strength of 2024-T86 after prior creep-exposure for time periods of 10-100 hours and an apparent decline in room-temperature ductility of 17-7PH (TH 1050) after prior creep exposure for 100 hours at temperatures near 600 F. WADC TR 57-150 36

BIBLIOG RAPHY 1. Armco Steel Corporation, Product Data Bulletin on Armco 17-7PH Steel, March 1, 1954. 2. Flanigan, A. E., Tedsen, L. F., Dorn, J. E., "Compressive Properties of Aluminum Alloy Sheet At Elevated Temperatures," Proceedings A. S. T. M. Vol. 46, pages 951-967, (1946). 3. Hyler, W. S., "An Evaluation of Compression-Testing Techniques for Determining Elevated Temperature Properties of Titanium Sheet," Titanium Metallurgical Laboratory, Battelle Memorial Institute, TML Report No. 43, pages 21, A-13 (June 8, 1956). 4. Muhlenbruch, C. W., "A Tension-Impact Test for Sheet Materials" A.S.T.M. Bulletin No. 196, page 43, February 1954. 5. Keller, F., "Metallography of Aluminum Alloys" from ASM Publication Physical Metallurgy of Aluminum by Fink et al - Cleveland, Ohio (1949) - p. 100. 6. Sperry, P. R. "The Intermetallic Phases in 2024 Alloy" Transactions ASM, Vol. 48, p. 904 (1956). 7. Decker, R. F., Rowe, J. P., Freeman, J. W. "Influence of Crucible Materials on the High-Temperature Properties of a Vacuum-Melted 55 Ni - 20 Cr - 15 Co - 4 Mo - 3 Ti - 3 Al Alloy." Engineering Research Institute, University of Michigan, Report 55 to The National Advisory Committee for Aeronautics, p. 7, January 18, 1957. 8. Hanlon, F., Salvaggi, J., Guarnieri, G. J., "Bimonthly Progress Report on Intermittant Stressing and Heating of Aircraft Structural Metals" Cornell Aeronautical Laboratory Report No. KB-892-M-12 to Air Research and Development Command on Contract AF 33(616)2226, Figure 1, (June 30, 1955). 9. Brisbane, A. W., "Mechanical Properties of 17-7PH Stainless Steel" WADC Technical Note 56-169, Table II, IV, (April 12, 1956). 10. Miller, D. E., "Determination of Physical Properties of Ferrous and Non-Ferrous Structural Sheet Materials at Elevated Temperatures" Report by Armour Research Foundation to WADC, AF Tech. Report No. 6517, Part 4, p. 132, 133 (December 1954). 11. Salvaggi, J., and Hanlon, F., "A Compilation of Data Summarizing the Effects of Intermittant Stressing and Heating of Aircraft Structural Metals", Cornell Aeronautical Laboratory, Report No. KB-892-M-13 to Air Research and Development Command on Contract AF 33(616)-2226, Table 2 (Aug. 31, 1955). 12. Fink, W. L., Smith, D. W., Willey, L. A., "Precipitation Hardening of High Purity Al-Cu Binary and Ternary Aly Age Hardening of Metals, published by American Society for Metals (1939). WADC TR 57-150 37

Table 1 r^~~~ ~Example Calculation of Effective Gage Lengths for 0tl~~~ ~Strip Specimens 17-7PH Alloy (TH 1050 Condition) H t-n^~ __________~~~~~Gage Length for Creep at 800~FfEltGgL t (f) [I}___________ Elastic Gage Length (a) (b) (c) (d) (e) Avg. Creep (e) (g) (h) Distancefrom Spec. Widths, Stress Creep Rate, Avg. Creep Creep at Center Rel. Area Area in GS Length of j Shoulder, inches inches (psi) (AL + AR)/hr Rate per 0. 050" per 0. 050" of Interval (g) Interval C 0 1.0050 55,400 0,.025 1.005 0.0255 0.050 0.9236 60,300 0.066 0.0455 0.001 0.924 0,0274 0.100 0.8466 65,800 0.095 0.0805 0.002 0.847 0.0299 0.150 0.7790 71,500 0.210 0.1525 0.004 0.779 0.0326 0.200 0.7210 77,300 0.470 0.340 0.008 0.721 0.0351 0.250 0.6707 83,100 1. 1 0.785 0.019 0.671 0.0377 0.300 0.6278 88,800 2. 2 1.65 0.039 0.628 0.0403 0.350 0.5916 94,200 4.8 3.50 0.083 0.592 0.0428 0.400 0.5622 99,000 9.5 7.15 0.170 0.562 0.0450 0. -450 0.5387 103,500 17.0 13.25 0.316 0.539 0.0470 0.500 0.5208 107,000 27.0 22.0 0.524 0.521 0.0485 0.550 0.5094 109,400 38.0 32.5 0.774 0.509 0.0498 Sum 1.940 Sum 0. 4616 = 0.46 Center 0.5064 110,000 42,.0 --- 0.506 U.) 00 PLASTIC CASE - 800~F ELASTIC CASE Effective Length 2 fillets = 2(1. 940)(0. 050) Effective Length 2 fillets = 2(0. 46)= 0. 92" = 0. 194" Shank Length = pin-pin minus shoulder-shoulder Shank Length = 1. 27" = 1. 82 - 3. 55 = 1.27 Equivalent Length of Shank: Equivalent Shank Length: (Creep Rate in Shank) (Gage Section Area) = 1.27 (0.506. 1.27 (Creep Rate at Center) =1.27 025) =Q 0008" 1.27 S hank Area )7 (1.005 Total Equivalent Length: Shank plus Fillets Total Equivalent Length: Shank plus Fillets 0. 0008 + 0.194 = 0.195" 0. 92 + 0.63 = 1.55" EFFECTIVE GAGE LENGTH = SHOULDER TO SHOULDER - ACTUAL FILLET + (EFFECTIVE SHANK PLUS FILLETS) EGL = SS - 2(0. 55) +0. 195 EGL = SS - 2(0. 55) + 1. 55 800~F elastic = SS - 0.905" = SS + 0. 45" Similarly EGL O = SS -1 01" (600"F) EGL F)= SS - 0.83" (900'F) And Similarly, for 2024-T86 with 0. 530" gage section width Elas tic gg g. Elastic EGL = SS + 0. 48" Plastic EGL = SS - 0.70"; EGL = SS - 0.90" (350~ and 400'F) (500~F)

U H a U-1 (i-I Table 2 Rupture and Total Deformation Data 17-7PH Alloy (TH 1050 Condition) Test Temp. Stress Rupture Time Elongati6n Reduction of Hardness after Loading Time to Reach Indicated Total Deformation - hours Spec. No, (OF) (psi) (hours) (% in 1 inch ) Area (%) test (R"C") Def.,% 0.5% 1.0% 2.0% 3.0% IK-T5 600 180,000 0. 1 4.0 13.1 44.4 IK-T2 180,000 broke on loading 4.0 0 42.3 U-TI 1;75,000 15.1 10.0 17.5 45.5 0.80 0.05 1.6 4.1 IC-T3 170,000 11.9 7.0 15.0 44.7 0. 75 0.4 2.5 57 IG-T O170,000 42.6 9.0 20.5 45.8 0.72 4. 0 4.6 120 IL-T6 165,000 98..8 12.5 20.5 44.3 0.69 -- 06 175 32.0 IC-T5 160,000 661.2 16.5 26.0 47.7 0.64 8.5 71.0 1520 2E-T1 150,000 stopped at 2515.2 hrs. -- -- --- 0.59 46.0 330.0 670'-0 2E-T5 125,000 stopped at 1893.3 hrs, -- -- -- 0.52 -- 20000* -01G-T5 800 105,000 37.3 22.0 37.0 46.3 0.47 0.05 0.3 0.8 13 3A-T6 100,000 61~3 43.0 44.0 46.8 0.41 0.1 1,9 6.4 102 IU-T3 100,000 107+5 32.0 44.0 46.0 0.41 0.1 2.3 8.5 60 IC-T4 95,000 179,.1 26.0 36.5 47.2 0.38 0.4 4.0 14,0 255 IU-T4 90,000 555.6 37.5 48.5 48.2 0.35 0.5 8.0 29.0 520 1Q-T25 70, 000 stopped at 1936.7 hrs. -- --- --- 0.26 7.0 90.0 850.0 IU-T5 900 75,000 19.8 31.0 46.5 46.9 0.32 0.10 1.U 29 46 IK-T4 70,000 29.1 28.0 49.0 46.1 0.29 0.20 1,2 3.4 5.7 IK-T6 70,000 56.7 38.5 52.8 45.9 0.30 0.25 1,4 4.6 77 IL-T5 70, 000 24.5 29.8 48.6 45.6 0.31 0.15 0.8 2,4 443 IC-T2 70,000 28.4 32.2 47.2 46.8 0.30 0.17 1.1 3.2 522 1K-T3 60,000 152.2 33.0 65.0 45.7 0.26 0.8 4.4 13,5 24,4 IG-T4 55,000 323.6 43.0 51.0 46.8 0.24 1.5 5,0 23,0 45,5 IC-T2 50,000 699.1 40.0 49.5 46.4 0.21 4.0 17,0 76,0 134,0 * Estimated

Table 3 H Rupture and Total Deformation Data 2024-T86 Aluminum Alloy (ji — j"^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~Time to Reach Indicated Total Deformation c*~~~~ ~ Test Temp. Stress Rupture Time Elongation Reduction of Loading (hrs) ^ Spec. Loc. ('F) (psi) (hrs) (%/2 in.) Area (%) Def. (%) 0.5%0 1.0%9 2.0% 3.0% 0 2B-T5 350 46, 000 20.4 6.0 8.8 0.51 -- approx. 7 3L-T11 45,000 24.5 4.2 9.2 0.47 0.08 -- -- 4A-T4 40,000 82.3 4.5 6.7 0.42 1.0 40.0 71.0 3E-T5 37,500 171.3 3.0 4.6 0.38 6.5 76.0 approx 7 2C-T1 35,000 481.2 2.8 4.1 0.37 19.5 256.0 4M-T4 32,000 460.5 2.0 5.1 0.32 31.5 310.0 2F-T11 30.000 (742.5)b -- -- 0.32 46.0 554.0 2P-T4 400 40,000 6.6 7.0 14.4 0.46 0.3 -- -- 3D-T3 37,500 19.2 5.0 8.1 0.41 0.5 8.1 18 (est) O 4M-T11 35,000 28.1 2.0 1.6 0.41 1.2 15.0 -- 3E-T11 30,000 (51.5)a 1.5 4.6 0.32 4.0 32.0 -- 2C-T5 30,000 83.1 4.0 6.6 0.33 4.0 43.5 76.5 2J-T5 25,000 360.6 3.5 6.2 0.29 23.0 169.0 354.0 4G-T5 20,000 (1127. 8)b -- -- 0.21 160.0 825.0 -- 3L-T2 500 25,000 1.7 7.0 20.4 0.34 0.06 0.51 1.05 1.5 2J-T2 20,000 8. 6 + 1 10.5 22,.0 0.26 1.1 4.0 -- 4G-TII 20,000 7. 1+1 5 11.0 27.4 0.27 0.6 2.6 2J-T11 19,000 22.8 9.2 13.1 0.22 2.4 7.9 2C-TII 15,000 113.1 9.2 16.3 0.16 11.1.42.4 -- 4A-T1 14,000 66.6 9.3 19.1 0.18 8.4 26.0 45.8 60 (est) 3D-T5 14,000 104.5 8.8 13.6 0.17 11.5 40.0 73.5 85 (est) 4A-TI1 10,000 461.0 8,.7 19.4 0.13 74.0 184.0 378.0 438.0 (a) failed at collar; collar on gage section in this instance (b) Test discontinued without failure

Table 4 Tensile Test Data for 2024-T86 Alloy Ult. Tensile 0.2% offset Reduction E Test Temp Strength Yield Strength Elongation of Area 6 Hardness (~F) Spec. No. (psi) (psi) (% - 2 inch) (%) (10 psi/in. /in.) (R"B") room 2P-T5 75,000 70,100 10.2 12.9 10.7 82. 5 2C-T2 75,800 70,900 7.2 12.7 10.9 82.0 2J-T3 76,100 70,800 8.0 8.9 11.0 79.7 Average 75,633 70,600 8.5 11. 5 10.9 81.4 3E-T1 74,500 69,400 8.0 19.0 10.4 79.5 3L-T3 75,400 70,800 7.2 13.6 11.3 79. 1 3L-T5 76,000 70,600 6.2 8.9 11.0 80.8 3E-T2 76,400 70,600 7.5 11.3 10.6 80.0 Average 75,575 70,350 7.2 13.2 10.8 79.8 4A-T5 75,200 70,000 8.0 8.6 10.7 79.9 4M-T3 77,500 72,000 7.5 10.6 10.9 78.9 4G-T2 75,000 70,400 8.0 12.2 10.7 80.8 Average 75,900 70,800 7 8 10.4 10.7 79.9 Average - 10 tests 75,690 70,560 7.8 11.9 10.8 80. 3 350 2B-T55 57,100 55,700 9.5 15.9 10.5 2F-T3 58,300 56,400 9.8 20.6 10.2 2M-T2 59,400 58,500 8.5 17.9 10.5 Average 58,267 56,867 9.3 18.1 10.4 3A-T11 56,900 55,500 9.5 20.3 10.6 3G-T3 58,100 56,900 9.0 19.1 10.0 3K-T2 57,500 56,700 10.0 20.0 9.9 Average 57,500 56,367 9.5 19.8 10.2 4C-T11 56,800 55,600 7.0 13.1 10.6 4H-X11 58,500 56,900 9.5 18.2 9.8 4Q-TI 58,100 56,900 9.5 17.4 10.3 Average 57,800 56,467 8.7 16.2 10.2 Average 9 tests 57,854 56,456 9.2 18.0 10.3 400 2D-T11 51,800 50,000 9.5 19.2 9.5 2F-T5 52,100 50,300 8.5 16.6 9.3 2M-T3 54,900 53,000 9.5 21.9 9.8 Average 52,933 51,100 9.2 19.2 9.5 3A-T2 54,600 52,300 10.8 20.4 9.0 3G-TI 51,700 50,000 9.0 19.6 9.4 3K-T1 51,700 49,600 8.0 18.6 9.3 Average 52,667 50,633 9.3 19.5 9.2 4C-T55 51,400 49,500 7.0 (9.0)* 9.3 4N-T2 52,300 50,700 10.0 18.3 9. 1 4P-T3 54,400 53,900 8.8 18.8 9.5 Average 52,700 51,700 8.6 18.6 9.3 Average 9 tests 52,784 51,033 9.0 19.2 9.4 500 2D-T4 37,600 35,200 9.5 23.9 7.3 2H-T3 38,900 38,000 9.5 21.6 7.7 2M-T1I 43,200 42,000 9.0 19.3 7.9 Aver.ge 39,900 38,400 9.3 21.6 7.6 3B-TI 38,400 36,900 8.8 23.1 7.4 3F-T3 40,200 39,100 8.5 25.1 7.7 3N-T5 40,300 38,400 9.5 20.7 7. 6 Average 39,633 38,133 8.9 22.6 7.6 4B-TI 42,600 -42,000 7.5 20.5 7.5 4E-T2 42,900 42,100 8.5 24.0 7.6 4N-T4 44,400 43,400 9.0 20. 1 7.9 Average 43,300 42,500 8.3 21.5 7.7 Average — 9 tests 40,944 39,677 8.8 21.9 7.7 * omitted from average - broke at gage point WADC TR 57-150 41

Table 5 Compression Test Data for 2024-T86 Alloy Elastic 0.2% offset Modulus Test Temp. Yield Strength 6 ("F) Spec. No. (psi) (10 psi/in./in.) room 2P-C4 74,100 10.7 2C-C1 77,800 10.2 2J-C4 76,000 10.5 2J-C3 73,000 10.2 Average 75,250 10.4 3E-C1 77,800 10.6 3E-C4 75,800 10.4 3L-C4 79,600 11.1 Average 77,730 10.7 4M-C3 69,200 10.6 4A-C2 72,600 10.1 4G-C3 76,100 10.1 Average 72,630 10.3 Average - 10 tests 75,200 10.4 350 2D-X4 63,900 10.6 2M-X1 66,600 10.2 2F-X1 70,800 10.2 Average 67,100 10.3. 3A-X1 65,600 10.2 3K-X5 69,800 10.2 3P-X5 67,600 10.3 Average 67,667 10.2 4N-X5 68,000 10.3 4H-X5 64,200 10.6 4C-X1 65,800 10.7 Average 66,000 10.5 Average - 9 tests 66,922 10.3 400 2M-X5 61,500 10.7 2K-X1 60,300 9.9 2B-X5 59,400 10.2 Average 60,400 10.3 3B-X5 60,200 10.3 3J-X5 60,500 9.9 3N-X1 61,200 10.4 Average 60,667 10.2 4Q-X1 61,800 10.0 4F-X1 60,000 9.8 4D-X1 61,400 10.2 Average 61,067 10.0 Average - 9 tests 60,711 10.2 500 2E-X1 51,500 8.8 2L-X1 49,800 8.8 2N-X1 48,400 8.6 Average 49,900 8.7 3D-X 48,100 9.3 3G-X5 50,800 8.6 3H-X1 49,700 8.9 Average 49,533 8.9 4B-X5 51,500 9.0 4J-X1 52,700 9.2 4P-X1 50,800 9.4 Average 51,667 9.2 Average - 9 tests 50,734 9.0 WADC TR 57-150 42

Table 6 Smooth-Bar Tension-Impact Test Data for 2024-T86 Alloy Energy Reduction Test Temp. Absorbed Elongation of Area ("F) Spec. No. a) (ft-lb) (% - 2 inch) (%) room 2C-M22 20 7. 5 7.0 2J-M2 19 6.5 13.7 2P-M22 16 5.5 9.3 Average 18.3 6.5 10.0 3E-M2 18 6.5 12.4 3E-M44 21 5.0 11.7 3L-M4 18 5.8 16.3 Average 19.0 5.8 13.4 4A-M2 20 4.5 11.6 4G-M22 14 4.0 6.2 4G-M4 20 7.5 13.7 4M-M4 16 5.2 9.2 Average 17.5 5.3 10.2 Average - 10 tests 18.2 5.8 11.2 350 2P-M5 14 2F-X2 19 Average 16.5 3L-M44 20.5 3E-M5 16 4.8 Average 18.2 4G-M5 16 4M-M5 16 4.0 4A-M5 17 4.5 Average 16.3 350~ - Average 16.9 4.4* 400 2C-M44 16 4.2 2N-X44 27 2P-M4 18 Average 20.3 3G-X2 24 6.2 4B-X44 16 4G-M2 14 4MM44 20 4.2 Average 16.7 400~ - Average 19.2 4.9* 500 2C-M2 14 5.0 2M-X44 18 5.5 2Q-M2 16 Average 16 3K-X44 15 4G-M44 17 4M-M2 18 4M-M22 16 4.8 Average 17 500~ - Average 16.2 5.3* * Average of 3 tests only a) Specimen gauge section 0. 200 in. wide x 0. 064 in. thick. WADC TR 57-150 43

Table 7 Notched-Bar Tension-Impact Data for 2024-T86 Alloy Temp Energy Absorbed (~F) Spec. No. a) (ft - lb) room 2C-X3 9 3M-X33 8 4L-X3 10 Average 9 350 2J-X3 8 4N-X3 8 Average 8 400 3E-X3 12 2C-X33 8 Average 10 500 4D-X3 8 3L-X3 7 Average 7.5 a) Minimum Cross Section at Notch 0. 250 in. wide x 0. 064 in. thick. Theoretical Stress Concentration factor, Kt = 4.2. WADC TR 57-150 44

Table 8 0) Room-Temperature Tensile Data for 17-7PH Alloy (TH 1050 Condition) mn Ult. Tensile 0.2% offset Strength Yield Strength Elongation Reduction of 6 Hardness Spec. No. (psi) (psi) % in Z inch Area (%) (10 psi/in. /in.) (R"C") o IC-T1 212,000 208,000 4.2 16.9 29.0 43.9 iL-T1 209,000 196,000 6.0 13.9 28.8 42.8 1L-T2 214,000 196,000 5.5 14.3 29.0 43.5 1L-T3 216,000 210,000 5.6 9.8 28.7 43.8 IL-T4 215,000 208,000 4.5 13.4 28.6 44.9 1U-T2 211,000 207,000 4.0 17.9 28.6 43.4 Average 212,833 204,160 5.0 14.4 28.8 43.7 " 2J-T3 197,000 186,000 9.0 19.4 27.6 43.4 2N-T3 187,000 173,500 8.8 21.7 29.3 42.3 Average 192,000 179,750 8.9 20.6 28.4 42.8 3G-T1 201,000 195,500 7.8 18.7 28.2 45.1 3Q-T1 202,000 195,000 7.2 20.8 29.2 44.3 Average 201,500 195,250 7.5 19.8 28.7 44.7 Average of 206,400 197,500 6.3 16.7 28.7 43.7 10 Tests Average of 203,100 193,050 7.1 18.2 28.6 43.7 Sheet Average

Table 9 Tensile Test Data at 600'F for 17-7PH (TH 1050 Condition) Elastic Ult. Tensile 0.2% offset Reduction Modulus Strength Yield Strength Elongation of Area 6 Spec. No. (psi) (psi) % - 2 inch (%) (10 psi/in./in.) 1G-T3 179,600 168,500 4.0 12.6 28.1 1P-T22 175,300 169,500 5.8 17.2 28.2 1P-T26 163,600 158,900 5.0 15.0 27.9 Average 172,833 165,633 4.9 14.9 28.1 2E-T2 183,000 168,700 4.5 16.1 29.3 2J-T4 156,900 148,000 5.2 14.8 27.4 2S-T4 186,900 179,000 5.2 16.1 27.2 Average 175,600 165,233 5.0 15.7 28.0 3A-T3 157,100 147,900 2.5 16.4 29.4 3F-T3 186,000 178,600 6.2 15.2 27.9 3P-T4 159,200 150,000 4.5 12.5 28.6 Average 167,433 158,833 4.4 14.7 28.6 Average 9 tests 171,989 163,233 4.8 15. 1 28.2 WADC TR 57-150 46

Table 10 Room Temperature Compression Test Data 17-7PH Alloy (TH 1050 Condition) 0.2% offset Compression Compression Modulus Yield Strength 6 Spec. No. (psi) (10 psi/in. /in. ) 1C-C44 242,000 29.5 1C-C4 235,000 30.1 1C-C22 228,000 29.6 1U-C4 226,000 29.6 Average 232,750 29.7 2J-C44 195,000 29.6 2E-C2 206,000 30.1 Average 2'00,500 29.8 3L-C6 205,000 29.8 3L-C4 234,000 29.6 3L-C44 216,000 30.3 Average 218,333 29.6 Average 9 tests 220,777 29.8 Average of sheet averages 217,194 29.8 0.2% offset Tension Tension Modulus Yield Strength (psi) (10 psi/in. /in.) Average of sheet 1 204,160 28.8 Average of sheet 2 179,750 28.4 Average of sheet 3 195,250 28.7 Average of 3 sheets 193,050 28.6 WADC TR 57-150 47

Table 11 Room-Temperature Tension-Impact Data 17-7PH Alloy (TH 1050 Condition) Notched Specimens Smooth Specimens Energy Energy Absorbed Absorbed Specimen No. (ft-lb) Specimen No. (ft-lb) 1G-M5 32 1C-M5 35 1G-M2 8 1C-M6 37 1U-M2 16 1C-M1 45 1U-M4 12 Average 17 Average 39 2E-M6 36 2J-M1 48 2N-M4 45 2J-M2 41 2N-M5 9 2E-M1 62 Average 30 Average 50.3 3F-M5 36 3L-M2 52 3F-M6 49 3L-M5 52 3L-M1 46 3F-M4 33 Average 47 Average 45.6 Average of 10 tests 28.9 Average of 9 tests 45.0 Average of sheet 31.3 Average of sheet 45. 0 averages averages Note: Notched Specimens 0. 250 inch wide at minimum section. Theoretical stress concentration factor Kt = 4. 2. Smooth Specimens 0.200 inch wide in gauge section. WADC TR 57-150 48

a>^~~~~~~ ~~~Table 12 Comparison of Tensile and Compression Properties Determined at the University of Michigan ok, or Elsewhere for 17-7PH Given the TH 1050 Treatment i O Tensile Properties Ult. Tensile 0.2% offset Test Temp Strength Yield Strength Elongation Hardness (~F) Source of Data (psi) (psi) (% - 2 inch) (Rockwell "C") room University of Michigan 203,100 193,050 7. 1 43. 7 600 171,989 163,233 4.8 ---- room Armco Steel Corporation Typical 200, 000 185,000 9.0 43 room (ref. 1) Minimum 180,000 150,000 6.0 F. 600 157,500 132,500 6.0 room Armour Research 195,900 183,200 8.8 43-44 600 Foundation (ref. 10) 177,700 166,600 3.8 room WADC (ref. 9) 209,200 197,000 6.5 45.5 room 193,000 177,400 8.5 43.0 600 155,200 164,900 5.0 room Cornell Aero. Lab. (ref. 11) 219,500 209,000 5.0 47-48 Compression Properties 0.2% offset Compression Yield Str. Test Temp Yield Strength Tensile Yield Strength (~F) Source of Data (psi) (%) room University of Michigan 219,194 112.3 room Armco Steel Corporation 110%o of Tensile Yield room Armco Research Foundation 195,000 106.8 room WADC 195,800 110.0

Table 13 Effect of Unstressed Exposure on Room-Temperature Tensile Properties of 2024-T86 Alloy C H- Ult. Tensile 0. 2% offset Reduction E l Temp Time Strength Yield Strength Elongation of Area 6 Hardness (OF) (hr) Spec. No. (psi) (psi) (% - 2 inch) (%) (10 psi/in./in.) (Rockwell "B") 1 350 10 2J-T1 74,900 69,000 7.5 9.2 10.9 79.3 _n 10 4A-T2 75,400 69,500 8.2 13. 8 10.1 80.7 0 75,150 69,250 7.8 11.8 10.5 80.0 50 2P-T1 73,300 66,100 7.5 9.9 11.0 77.8 50 4G-T3 74,500 65,900 7.5 8,.1 10.8 77.2 73,900 66,000 7.5 9.0 10.9 77.5 100 2P-T3 71,600 63,500 7.5 11.1 10.8 75.8 100 3M-T1 71,500 63,200 7.0 11.0 10.8 75.8 71,550 63,350 7.2 11.0 10.875.8 (-i 0 400 10 2P-T2 71,600 63,900 6.5 15.3 11.0 75.8 10 4G-T1 71,200 63,300 6.5 12.3 11.0 74.7 71,400 63,600 6.5 13.8 11.0 75.2 50 3E-T4 67,000 56,900 7.5 12.9 11.0 72.0 50 4M-T2 66,600 56,500 7.5 11.4 11.3 71.3 66,800 56,700 7.5 12.2 11.2 716 100 2C-T3 64,500 53,800 7.5 12.1 10.7 68.2 100 3L-T1 64,300 53,800 7.5 13.0 11.3 68.7 64,400 53,800 7.5 12.6 11.0 68.4 500 10 2P-T1l 62,500 50,100 7.0 10.0 10.6 65.3 10 3E-T3 61,500 49,300 7.0 12,.6 10.4 66.8 62,000 49,700 7.0 11.3 10.566.0 50 2C-T4 62,400 50,300 7.5 10.0 10.8 68.0 50 4G-T4 59,900 48,500 7.0 11.7 o10.6 66.1 61,150 49,400 7.2 10.8 10.767.0 100 3L-T4 51,500 37,000 7.0 13.0 10.9 54,3 100 4A-T3 52,100 38,800 b.5 13.6 10.6 54.7 51,800 37,900 6.8 13.3 10.8 54,5

Table 14 Effect of Unstressed Exposure on Elevated-Temperature Tensile Properties of 2024-T86 Alloy Tensile Test Results Exposure Conditions Tensile Test Ult. Tensile 0.2% offset Reduction E iemp -llime Temperature Strength Yield Strength Elongation of Area 6 _] ('F) (hrs) (~F) Spec. No. (psi) (psi) (% - 2 inch) (%) (10 psi/in./in.) ~- 350 10 350 3G-T4 59,800 57,900 9.0 17.3 10.2 0n 350 10 350 2B-T2 59,600 58,600 8.8 14.2 10.4 Average 59,700 58,250 8.9 15.8 10.3 350 50 350 3K-T4 57,000 55,000 6.5 11.4 10.1 350 50 350 4C-TI 57,200 56,000 10.5 21.2 10. 1 Average 57,100 55,500 8.5 16.3 10.1 350 100 350 3D-T1 56,900 56,000 7.5 15.0 9.9 350 100 350 4Q-T11 58,300 56,800 9.8 16.4 10.1 Average 57,600 56,400 8.6- 15.7 10.0 400 10 400 3A-T55 53,500 51,000 9.5 18.1 9.3 0- 400 10 400 4P-T1 55,100 53,400 9. 5 19.0 9.4 Average 54,300 52,200 9.5 18.5 9.4 400 50 400 2D-T1 52,500 50,600 8.5 21.9 9.8 400 50 400 3N-T3 54,300 53,700 10.0 17.6 9.6 Average 53,400 52,150 9.2 19.8 9.7 400 100 400 2H-T4 52,100 50,500 10.0 17.8 9.0 400 100 400 4E-T1 54,700 54,000 10.0 23.6 9.7 Average 53,700 52,250 10.0 20.7 9.4 400 100 400 a)5B-T3 55,400 52,100 9.2 18.9 9.1 500 10 500 2D-T2 39,800 38,000 9.0 26.4 7.6 500 10 500 4N-T55 40,400 38,300 8.8 20.2 7.8 Average 40,100 38,150 8.9 23.3 7.7 500 50 500 3B-T2 39,600 38,300 9.0 23.9 7.8 500 50 500 4B-T11 38,600 37,300 8.0 23.9 8.3 Average 39,100 37,800 8.5 23.9 8.0 500 100 500 3F-T55 39,500 38,300 9.0 23.6 7.8 500 100 500 2L-TII 37,700 35,600 10.5 26.0 7.5 Average 38,600 36,950 9.8 24.8 7.6 500 100 500 a)5H-T5 44,000 35,400 8.2 21.5 8.1 a) Specimens Not Rerachined Prior to Tensile Test

Table 15 Effect of Prior Creep-Exposure on Tensile Properties and Hardness of 2024-T86 Alloy C3 Nominal Exposure Conditions Tensile Properties After Exposure Total Actual Exposure Conditions Deformation Obtained (%) Ult. Tensile 0.2% offset Reduction Modulus E Temp Time Deformation Time Temp Stress Loading Loading Test Temp Strength Yield Strength Elongation of Area 6 Hardnes ('F) (hr) (%) Spec. No. (hr) (~F) (psi) (Total) (Plastic) Creep Total ('F) (psi) (psi) ( % - 2 inch) (%) (10 psi/in.in.) Rockwell"B" (0 350 10 0.5 4H-T5 10. 1 350 36,000 0.36 0.01 0. 16 0.52 room 74,800 68,600 8.5 13.8 10.7 78.2 10 0.5 3A-T1 10.1 350 36,000 0.40 0.01 0. 15 0.55 room 74,500 68,200 9.0 9.3 10.6 79.0 10 1.0 2F-T4 10.4 350 44,500 0.51 0.03 0.62 1.13 room 73,600 68,000 7.0 14.2 10. 7 80.2 10 1.0 4C-T2 10.3 350 44,500 0.49 0.03 0.38 0.87 room 74,500 68,800 7.0 10.5 10.9 79.7 10 2.0 3K-T11 10.1 350 47,000 0.53 0.04 1.09 1.62 room 74,300 69,200 10.0 12.6 10. 8 79. 3 10 2.0 4B-T3 10.2 350 47,000 0.55 0.04 1.35* 1.90* room 73,100 68,300 5.8 9.4 10.9 80.8 10 0.5 4C-T5 10.4 350 36,000 0.37 0.01 0.16 0.53 350 57,500 56,500 9.0 19.9 10.6 80.2 10 0.5 3D-T22 10.0 350 36,000 0.38 0.01 0.15 0.53 350 57,600 56,500 10.5 17.2 10.1 80.3 10 1.0 3N-T1 10.1 350 44,500 0.48 0.03 0.44 0.92 350 56,100 55,600 9.5 19.2 10.0 ---- 10 2.0 2L-T55 10.0 350 47,000 0.55 0.04 1.35* 1.90* 350 56,200 56,100 3,5'10.1 10.2 ---- 50 0.5 3A-T4 50.2 350 30,000 0.33 0 0.21 0.54 room 72,900 65,600 8.0 11.1 11.0 79.0 50 0.5 2N-T55 50.0 350 29,000 0.30 0 0.15 0.45 room 72,900 66,100 6.8 11.4 11.4 79.7 N\) 50 1.0 3G-T55 50.0 350 39,500 0.42 0.02 0.68 1.10 room 69,800 62,400 8.5 10.8 10.7 76.8 50 1.0 4P-T11 50.1 350 39,500 0.41 0.02 0.43* 0.84* room 71,900 64,900 7.5 9.2 10.8 77.7 50 2.0 3G-T1 50.3 350 41,000 0.47 0.02 1.05 1.52 room 71,200 63,900 5.5 8.1 11.0 77.5 50 2.0 4J-T3 50.2 350 41,500 0.46 0.02 1.35 1.81 room 69,800 63,300 5.0 5.9 10.8 77.5 50 0.5 2Q-11 50.0 350 29,000 0.29 0 0.15 0.44 350 56,300 54,600 9.0 19.6 9.9 77.7 50 1.0 2E-T3 53.3 350 39,500 0.42 0.02 0.66 1.08 350 54,500 53,600 9.2 18. 1 10.5 ---- 50 2.0 2A-T2 50.1 350 41,500 0.47 0.02 1.06 1.53 350 53,800 53,000 7.0 15.5 9.8 80.2 100 0.5 2M-T5 100.1 350 28,000 0.29 0 0.24 0.53 room 69,800 61,500 7.0 9.2 10.4 76.0 100 0.5 4F-T4 102.5 350 28,000 0.28 0 0.18 0.46 room 72,600 64,600 8.0 11.9 10.8 79.0 100 1.0 4P-T4 100.0 350 37,500 0.42 0.01 0.71* 1.13* room 71,700 62,900 8.5 10.8 10.7 76.8 100 1.0 2H-T1 100.2 350 37,500 0.41 0.01 0.70 1. 11 room 70,800 62,600 7.0 9. 1 11.0 76.5 100 2.0 3K-T5 100. 1 350 39,000 0.43 0.02 1.52 1.95 room 65,100 60,000 5.0 4.7 10.9 78.3 100 2,0 2E-T2 100.0 350 39,000 0.42 0.02 1.55* 1.97* room 67,400 60,500 4.0 4.7 10.6 78.5 100 0.5 3H-T3 100.0 350 28,000 0.27 0 0.19 0.46 350 53,400 51,500 11,0 18,8 9.9 77.3 100 1,0 3B-T3 99.8 350 37,500 0.39 0.01 0.68 1.07 350 53,000 51,900 8.2 13.2 10.1 ---- 100 2,0 2N-T3 100.0 350 39,000 0.40 0.02 2.04 2.44 350 48,300 48,000 2.0 6.5 9.8'79.0 * Estimated

Table 15 (continued) Effect of Prior Creep-Exposure on Tensile Properties and Hardness of 2024-T86 Alloy C H Nominal Exposure Conditions Tensile Properties After Exposure -^ ~ ------- Total Actual Exposure Conditions Deformation Obtained (%l) Ult. Tensile 0. 2% offset Reduction Modulus E _ Temp Time Deformation Time Temp Stress Loading Loadigng Test Temp Strength Yield Strength Elongation of Area Hardness (IF) (hr) (%) Spec. No. (hr) ('F) (psi) (Total) (Plastic) Creep Total ("F) (psi) (psi) (%l - 2 inch) (%) (10 psi/in, /in.)Rockwell "B" 400 10 0.5 2B-T1 10.0 400 28,000 0.32 0.01 0.34 0.66 room 68,800 59,300 7.5 11.3 10.6 74.3 ~-*J~ ~ 10 0.5 3A-T3 10.0 400 28,000 0.32 0.01 0.27 0.59 room 70,000 61,200 7.8 12.5 10.9 76.5 J1 10 0.5 4C-T3 12.4 400 28,000 0.57 0.26 0.25 0.82 room 70,500 60,900 8.0 14.8 10.5 76.1 C 10 1.0 3D-Tll 10.7 400 36,000 0.40 0.04 0.73 1.13 room 69,000 60,000 8.0 14.2 10.9 75.0 10 1.0 4Q-T2 10.0 400 36,000 0.40 0.04 0.81 1.21 room 68,800 60,400 5.5 11.1 10.6 77.7 10 1.0 4C-T4 12.3 400 36,000 0.42 0.04 0.97 1.39 room 68,600 59,200 8.5 12.3 10.9 74.3 10 2.0 2N-TIl 10.2 400 37,000 0.44 0.04 0.83 1.27 room 70,100 61,500 8.0 11.8 10. 9 10 2.0 2E-T55 rupt. 10.0 400 37,500 0.47 0.05 2.23 at 9.8 hrs. ---- -- -- -- 10 0.5 2D-T44 10.2 400 28,000 0.31 0.01 0.22 0.53 400 48,000 46,700 10.0 22.4 9.2 78.2 10 1.0 2M-T5 10.5 400 36,000 0.42 0.04 0.73* 1,15* 400 46,000 45,600 7.8 17.9 9.3 --- 10 2.0 4K-T2 10.0 400 37,000 0.40 0.04 1.29 1.69 400 47,000 46,400 7.8 15.3 9.4 76.2 50 0.5 4H-T1 50.1 400 23,000 0.24 0 0.29 0.53 room 65,300 55,100 8.0 9.6 10.8 71.3 50 0.5 3K-T3 50.3 400 23,000 0.26 0 0.32 0.58 room 66,600 56, 000 8.5 10.6 10.7 73.2 (3 50 1.0 3K-T55 50.1 400 29,000 0.34 0.01 0.62 0.96 room 65,900 56,000 7.5 8.6 11.3 72.1 C(j0 ~ ~ 50 1.0 2D-T5 52.5 400 29,000 0.34 0.01 0.88 1.22 room 64,300 53,000 7.0 10.9 10.8 69.5 50 1.0 2B-T4 50.1 400 30,000 0.35 0.01 1.08 1.43 room 64,500 53,800 7.0 10.6 10.7 70.8 50 2.0 2M-T4 49.2 400 31;500 0.33 0.02 1.02 1.35 room 64,100 53,600 5.8 8.2 10.8 74.3 50 2.0 4D-TI1 50.0 400 31,500 0.35 0.02 0.79 1.14 room 65,400 55,200 7.5 11.4 10.5 71.8 50 2.0 3F-T1 rupt. 42.2 400 32,000 0.36 1.38 at 34 hrs. ---- -- -- -- 50 0.5 2E-T11 50.1 400 23,000 0.25 0 0.34 0.59 400 44,800 42,700 10.0 22.9 9.1 ---- 50 1.0 4N-T3 50.4 400 29,000 0.33 0.01 1.03 1.36 400 42,500 41,000 8.0 15.1 9.5 ---- 50 2.0 5C-T2 50.0 400 31,500 0.30 0.02 1.34 1.64 400 42,900 41,700 4.5 8.4 9.3 72.3 100 0.5 3D-T4 100.0 400 21,000 0.24 0 0.25 0.59 room 64,500 53,100 9.0 14.6 10.9 70.0 100 0.5 4H-T55 100.2 400 21,000 0.22 0 0.33 0.55 room 64,500 53,900 8.5 11,7 11.0 68.9 100 1.0 4H-T3 100.3 400 27,000 0.29 0.01 0.78 1.07 room 61,800 50,800 11.0 11.7 10.4 69.0 100 1.0 3B-TI1 100.1 400 27,000 0.30 0.01 0.77 1.07 room 63,800 52,000 7.0 10.4 10.8 70.7 100 2.0 3A-T5 100.0 400 29,000 0.28 0.01 1.25 1.53 room 60,600 50,900 5.5 7.5 10.9 71.0 100 2.0 4D-T3 100.0 400 29,000 0.33 0.01 1.27 1.60 room 62,200 23,800 6.5 7.3 10.6 70.5 100 2.0 2K-Tll1 rupt. 82.8 400 29,500 0.30 0.01 1.60 at 72 hrs. ---- -- -- -- 100 0.5 2H-T2 100.0 400 21,000 0.23 0 0.37 0.60 400 41,900 39,800 10.7 23.9 9. 3 100 0.5 3F-T5 100.4 400 21,000 0.22 0 0.35 0.57 400 43,600 41,000 11.0 24.6 9.6 100 1.0 3F-T2 99.6 400 27,000 0.30 0.01 0.98 1.28 400 41,800 39,800 9.0 15.9 9.8 71.3 100 1.0 2M-T55 100.0 400 27,000 0.30 0.01 0.94 1.24 400 40,800 38,500 7.0 12.9 9.4 71,3 100 2.0 5G-T5 100.2 400 29,000 0.30 0.01 1.85 2.15 400 37,600 37,100 2.2 3.1 8. 5 * Estimated

Table 15 (concluded) Effect of Prior Creep-Exposure on Tensile Properties 0) and Hardness of 2024-T86 Alloy Nominal Exposure Conditions Tensile Properties After Exposure (,'Total Actual Exposure Conditions Deformation Obtained (%) Ult. Tensile 0. 2% offset Reduction Modulus, E ",, Temp Time Deformation Time Temp Stress Loading Loading Test Temp Strength Yield Strength Elongation of Area 6 Hardness (F) (hr) (%) Spec. No. (hr) (~F) (psi) (Total) (Plastic) Creep Total (~F) (psi) (psi) ( % - 2 inch ) (% (10 psi/inin.) Rockwell "B" o500 10 0.5 2F-T55 10.2 500 14,500 0.17 0 0.30 0.47 room 53,500 38,900 7.8 10.6 10.5 60.2 ^O 10 1.0 4N-T5 10.0 500 17,000 0.20 0 0.89 1.09 room 48,100 33,700 8.0 14.2 10.5... 10 1.0 4P-T5 rupt. 7.4 500 18,000 0.23 0 2.00 at 6 hrs. -- -- -- -- -- 10 1.0 4H-T4 10.0 500 18,000 0.22 0 1.34 1.56 room 48,900 33,400 8.0 13.9 10.7 50.3 10 2.0 2D-T3 10.4 500 19,000 0.24 0 2.75* 3.00* room 50,300 35,700 7.2 14.2 10.7 57.7 10 3.0 4E-Tll 10.0 500 19,500 0.23 0 3.25* 3.50* room 51,400 36,200 7.8 12.1 10.4 58.2 10 3.0 4N-TII rupt. 10.2 500 19,800 0.25 0 0.89 at 3.75 hrs. -- -- -- -.... 10 0.5 4B-T5 10.2 500 14,500 0.23 0 0.40 0.63 500 28,200 26,300 7.2 29.6 7.9 57.2 10 1.0 2N-T2 10.4 500 17,000 0.22 0 0.57 0.79 500 27,900 26,200 10.0 24.4 8.2 58.3 10 2.0 4L-TIl 10.0 500 19,000 0.26 0 2.67 2.93 500 23,100 22,800 6.0 13.8 8.3 54.3 50 0.5 4P-T55 53.6 500 11,000 0.12 0 0.68* 0.80* room 42,200 25,000 10.2 18.4 10.7 35.3 50 0.5 3Q-T2 50.0 500 11,000 0.12 0 0.63* 0.75* room 47,500 30,900 10.0 13.3 11.3 48.7! ~50 1.0 2H-T 11 50.0 500 13,000 0.14 0 0.85 0.99 room 45,800 31,100 8.0 14.2 10.4 45.8 50 1.0 3G-T5 rupt. 9.5 500 14,000 0.17 0 -- -- -- -- -- -- -- -- 50 1.0 3G-T2 50.3 500 14,000 0.17 0 1.42 1.59 room 46,100 29,400 10.0 15.7 10.6 45.0 50 2.0 3J-TI 50.0 500 14,000 0. 16 0 0.98 1. 14 room 48,700 32,400 9.5 13. 1 11.0 50.2 50 3.0 3B-T5 50.1 500 15,000 0.20 0 3.23 3.43 room 42,100 27,400 7.2 18.0 10.5 45.0 50 3.0 3P-T4 rupt. 47.2 500 15,500 0.18 0 3.35 at 42 hrs. -- -- -- -- --. 50 3.0 2K-T2 rupt. 39.2 500 15,250 0.18 0 1.27 at 22 hrs. -- -- -- -- -- 47.2 50 0.5 5G-TI 50.0 500 11,000 0.14 0 0.46 0.60 500 22,100 20,100 13.0 28.7 9.7.... 50 1.0 4B-T55 50.1 500 13,000 0.17 0 1.09 1.26 500 20,600 18,900 10.8 28.7 7.7 46.8 50 2.0 5M-T2 50.0 500 14,000 0.16 0 2.15 2.31 500 20,800 19,500 10.0 30.6 7.7 45.0 50 3.0 5G-T4 53.2 500 15,000 0.17 0 2.94 3.11 500 20,500 19,900 11.5 33.0 8.1 49.3 100 0.5 3D-T55 100.0 500 9,000 0.11 0 0.51 0.62 room 44,400 28,200 9.8 17.5 10.7 38.8 100 0.5 4J-T4 100.0 500 9,000 0.11 0 0.75 0.86 room 38,000 21,600 12.0 23.6 10.3 30.3 100 1.0 2M-TI 99.9 500 12,000 0.14 0 0.95 1.09 room 44, 100 28,700 8.0 14.1 10.8 43.5 100 1.0 4F-T2 100.0 500 12,000 0.15 0 3.20 3.35 room 39,600 22,800 10.0 14.7 10.4 30.5 100 2.0 4B-T2 100.0 500 12,500 0.17 0 1.72 1.89 room 42,300 25,900 9.0 14.3 10.7 42.0 100 3.0 3N-T4 100.0 500 13,000 0.15 0 3.10 3.25 room 41,000 23,100 8.5 15.6 10.9 37.3 100 3.0 2L-T5 rupt. 80.5 500 13,700 0.17 0 3.43 at 72 hrs. -- -- -- -- --. 100 3.0 3P-T55 rupt. 91.1 500 13,400 0.16 0 3.05 at 82.5 hrs. -- -- -- -- -- 42.7 100 0.5 2N-T2 100.0 500 9,000 0.12 0 0.76 0.88 500 20,800 18,200 16.5 38.8 8.0 32.8 100 1.0 3B-T55 100.0 500 12,000 0. 14 0 1.24 1.38 500 22,100 19,800 13.8 35.3 8.0 37.5 100 2.0 2A-T4 rupt. 59.0 500 12,500 0. 16 0 2.68 at 58 hrs. -- -- -- -- - 40.0 100 3.0 4D-T1 rupt. 91.9 500 13,000 0.14 0 2.67 at 89 hrs. -- -- -- -- -- 42.0 * Estimated

Table 16 Effect of Stressed and Unstressed Exposure on Room-Temperature Tensile Properties of 17-7PH Alloy in the TH 1050 Condition Exposure Comliins Room Temperature Tensile Properties Pla.,;ii, Total Ult. Tensile 0.2% offset Ternp Stress Time T'ol'tl IDl. I.o lding leeodng LD/TD Strength Yield Strength Elongation Reduction of Hardness Spec. No. (*F) (psi) (lhr) (%D 1.7,'.,% ( psi) (psi) ('Io in Z inch) Arear() (10 psi/in./in.) (R"C") Average Properties - 3 sheets - As treated 203,000 193,050 7.1 18.Z 28.6 43.7 2E-T4 600 None 1 0 No,,, 192,000 183,000 8.5 20.0 30.2 40.9 3P-T3 600 None 10 Noneee 209,000 203,000 6.5 19.7 30.4 43.4 A% eraz. e 200,500 193,000 7.5 19.8 30.3 42.2 1P-T21 6000 None 50 None 193,000 186,000 10.5 18.3 30.4 42.0 3L-T5 600 None s0 Ntone' 187,000 180,000 9.0 22.6 31.2 41.6 A% erage 190,000 183,000 19.8 20.5 30.8 41.8 2N-T4 600 None 100 Notne. 192,500 184,200 8.0 18.4 29.4 42.5 3A-T1 600 No 100age 212,000 206,000 7.5 19.4 29.8 45.8 A\ e.rage 202,250 195,100 7.8 18.9 29.1 45.3 2N-TI 600 157,000 100.5 1.8 0.0 0.60 31.8 223,000 (223,000) 1.5 13.7 29.4 45.3 3Q-T7 600 157,000 100.4 3.82 0.72 18.9 209,000 -- 2.0 8.6 30.3 41.1 IP-T24 600 157,000 09, 5.30 0.75 14.-1 217,500 (188,500) 2.0 5.8 28.9 42.8 A erage 3.t07 216,500 (205,750) 1.8 9.7 29.5 43. 1 2S-T3 650 137,000 105.0 1.87 0.5.0 26.8 215,000 215,000 2.5 12.5 30.4 43.5 3B-T4 650 137,000 100.1 2.71 0.05 0.63 23. 206,000 206,000 2.5 14.0 31.8 41.7 Average 2.29 210,500 210,500 2.5 13.2 31.1 42.6 2R-T6 700 118,000 100.2 1.82 0.47 25.8 211,000 210,000 4.0 17.7 29.6 42.8 3G-T3 700 118,000 100.7 1.60 0.015 0.42 26.2 218,500 218,000 3.0 16.0 30.8 44.9 Average 1.71 214,750 214,000 3.5 16.8 30.2 43.8 2R-T2 700 120,000 100.1 2.54 0.50 19.7 219,000 218,000 2.2 13.7 30.6 44.0 3Q-T6 700 120,000 100.1 1.95 0.43 22.1 220,000 219,000 3.5 13.8 29.6 44.2 Average2.24 219,500 218,500 2.8 13.8 30.1 44.1 2J-T5 750 101,000 100.0 1.94 0.42 21.6 222,000 220,000 3.0 17.0 29.7 44.2 3B-T3 750 101,000 100.0 1.62 0.25 15.4 218,000 217,000 4.5 16.7 30.0 46.1 Average 1.78 220,000 218,500 3.7 16.8 29.8 45.2 3H-TI 800 None 10 None 201,000 195,000 07.5 18.7 30.8 43.8 ZR-T3 800 None 10 None 192,000 187,000 5.0 16.9 29.8 41.9 Average 196,500 191,000 6.2 17.8 30.3 42.8 2S-T2 800 None 50 None 218,000 213,000 4.9 15.1 31.2 43.6 IQ-T23 800 None 50 None 220,000 215,000 6.0 17.9 30.4 45.5 Average 219,000 214,000 5.4 16.5 30.8 44.6 3G-T6 800 None 100.0 None 222,000 216,000 4.0 17.9 29.8 47.4 2N-T2 800 None 100.0 None 222,500 216,000 5.0 17.3 30.2 48.2 Average 222,250 216,000 4.5 17.6 30.0 47.8 3P-TI 800 81,000 102.6 2.12 0.31 14.6 232,000 229,000 3.5 12.1 29.9 46.7 2S-T6 800 81,000 102.1 1.88 0.32 17.0 227,000 222,000 4.2 15.8 30.2 46.7 Average 2.00 229,500 225,500 3.8 14.0 30.1 46.7 ZR-T5 850 66,000 100.0 1.99 0.26 13.1 235,000 230,000 5.0 13.4 30.8 46.4 3H-T3 850 66,000 100.1 2.09 0.008 0.29 13.9 231,000 228,000 4.2 14.3 30.0 47.6 Average 2.04 233,000 229,000 4.6 13.8 30.4 47.0 IP-T23 900 None 10 None 205,500 200,000 6.5 17.2 30.2 43.1 3A-T5 900 None 10 None 206,500 201,000 5.0 182 308 44.2 Average 206,000 200,500 5.8 17.7 30.5 43.6 2S-TI 900 None 50 None 230,000 224,000 3.5 14.1 30.9 46.2 3H-T6 900 None 50 None 234,000 228,500 5.0 13. 730.6 47.0 Average 232,000 226,500 4.2 13.9 30.8 46.6 3P-T6 900 None 100.0 None 222,000 215,000 4.5 8.4 30.4 46.2 2N-T5 900 None 100.0 None 220,000 213,000 6.0 171 28.8 470 Average 221,000 214,000 5.2 12.8 29.6 46.6 2R-TI 900 49,000 100.0 1.55 0.19 12.2 214,000 209,000 6.5 16.7 29.9 45.3 3G-T2 900 50,000 100.0 2.04 0.005 0.22 10.8 224,000 219,000 4.0 15.2 29.7 46.8 1Q-T22 900 50,000 100.0 2.33 0.20 8.6 235,000 230,000 4.0 13. 1 30.0 48.1 Average 1.97 224,333 219,333 4.8 15.0 29.5 46.7 gage section not remachined before tensile test, aL. D.= Total Loading Deformation; 1T. D.= Total Deformation at end of Crerep-Exposure period. WADC TR 57-150 55

Table 17 Tensile and Yield Strengths of 2024-T86 after Specified Exposure, Expressed as Percentage of Unexposed Value at Test Temperature Exposure Temp Exlxosure Time Total D)ef. Test Temp Percent of Unexposed Percent of Unex,osed ('F) (hr), (%) (IF) Tensile Strength Yield Strength nonen none noneroom75,690 psi 70,800;si none none none 350 57,854 psi 56,456 si 350 10 none room 99.5% 98.0% 0. 5 room 97.5 97.5 1.0 room 97.0 97.2 2.0 room 95.8 96.5 10 none 350 103.0 103.9 0.5 350 98.6 100.2 1.0 350 97.6 99.8 2.0 350 96.8 98.4 50 none room 97.8 93.2 0.5 room 96.2 92.3 1.0 room 94.9 91.0 2.0 room 91.9 89.0 50 none 350 99.3 100.0 0.5 350 97.0 96.8 1.0 350 94.8 95.2 2.0 350 90.3 93.5 100 none room 94.4 89.5 0.5 room 94.2 89.0 1.0 room 94.0 89.0 2.0 room 87.0 84.7 100 none 350 99.3 100.0 0.5 350 92.4 91.5 1.0 350 91.4 91.3 2.0 350 85. 7 87.0 none none none room 75,690 psi 70,800 psi none none none 400 52,784 psi 51,033 psi 400 10 none room 94.0% 93.2% 0.5 room 92.9 86.1 1.0 room 91.8 85.2 2.0 room 89.4 84.4 10 none 400 102.2 100.8 0.5 400 91.5 91.0 1.0 400 88.2 91.0 2.0 400 90.0 96.9 50 none room 88.5 80.4 0.5 room 87.5 78.9 1. 0 room 86.2 77.6 2.0 room 83. 5 74.9 50 none 400 101.2 100.9 0.5 400 87.2 86. 1 1.0 400 82.5' 82.0 2.0 400 82.3 83.0 100 none room 85. 3 75.6 0.5 room 85.0 74.8 1.0 room 83.6 73.4 2.0 room 79.8 69.8 100 none 400 100.3 102.3 0.5 400 84.3 82.2 1.0 400 79.5 77.5 2.0 400 75.4 74.9 none none none room 75, 690 psi 70,800 psi none none none 500 40,944 psi 39,677 psi 500 10 none room 82.0% 70. 0% 0.5 room 70.6 53.6 1.0 room 64.7 48.1 2.0 room 65.0 48. 1 3.0 room 66. 7 50.2 10 none 500 97.5 96.2 0.5 500 78.4 75.6 1.0 500 66.8 64.3 2.0 500 61.2 59.2 3.0 500 55.5 54.2 50 none room 79.9 69.2 0.5 room 67.4 52.3 1.0 room 61.-i 43.0 2.0 room 58.8 41.0 3.0 room 56.5 38.8 50 none 500 96.4 94.5 0.5 500 74.7 70.5 1.0 500 53.9 48.1 2.0 500 50.4 49.1 3.0 500 50.2 49.4 100 none room 68.0 53.6 0.5 room 60.1 42.4 1.0 room 54.9 36.2 2.0 room 54.2 34.9 3.0 room 53.5 33.2 100 none 500 94.2 93.4 0.5 0 500 74.7 70.5 1.0 500 53.9 48.4 2.0 500 50. 49. 1 3.0 500 50.2 49.4 WADC TR 57-150 56

Table 18 Effect of Unstressed Exposure on Room-Temperature Compression Properties of 2024-T86 Alloy Compression Test Results 0. Z7o offset Compression Exposure Conditions Compression Modulus Temp Time Yield Strength 6 (~F) (hrs) Spec. No. (psi) (10 psi/in./in.) 3500 10 2C-X2 74,100 10.3 10 4A-X44 74,500 10.6 _,.. _.,,, 1 Average 74,300 10.4 50 3E-X2 72,000 10.9 50 4A-X2 71 500 11.0 Average 71,750 11.0 100 2J-X44 66,900 10.5 100 4G-X33 69,900 10.9 Average 68,400 10.7 4000 10 3L-X33 65,400 11.0 10 4G-X44 65,200 10.8 Average 65,300 10.9 50 2P-X44 59,500 10.7 50 4G-X2 59,700 10.8 Average 59^600 10.8 100 2P-X2 53,900 10.6 1 00 4A-X33 57,300 10.3 Average 55,600 10.4 500 10 2J-X2 47,300 10.5 10 4M-X2 45,500 11.3 Average 46,400 10.9 50 3L-X2 57,500 11.2 50 4A-X22 56,500 10.6 Average 57,000 10.9 100 2J-X33 51,500 10.5 100 3E-X44 51,300 10.6 Average 51,400 10.6 WADC TR 57-150 57

Table 19 Effect of Unstressed Exposure on Elevated-Temperature Compression Properties of 2024-T86 Alloy Compression Test Results. 0Zo offset Compression Exposure Condition Compression Compression Modulus Temp. Time Test Temp Yield Strength 6 (~F) (hrs) (~F) Spec. No. (psi) (10 psi/in. /in.) 350 10 350 2L-X5 64,300 10.0 350 10 350 3D-X5 64,500 10.4 64,500 10.2 350 50 350 4N-X1 64,600 10.2 350 100 350 3J-X1 65,000 10.3 350 100 350 4D-X5 65,000 10.5 65,000 10.4 400 10 400 3G-X1 58,100 9.8 400 10 400 4E-X5 55,800 9.7 56,950 9.8 400 00 50 400 3P-X1 51,600 9.9 400 50 400 4N-X5 52,400 9. 8 52,000 9.8 400 0 0000 02N-X1 50, 600 9.6 400 100 400 3L-X44 50,600 9.9 50,600 9.8 500 10 500 2B-X1 36,600 9.3 500 10 500 4M-X44 35,200 9.1 35,900 9.2 500 50 500 2H-X1 30,800 9.0 500 50 500 3A-X5 32,400 8.5 31,600 8.8 500 100 500 4H-X1 22,900 9. 1 500 1 00 500 2D-X1 24,600 9. 1 23,750 9.1 WADC TR 57-150 58

Table 20 Effect of Prior Creep Exposureon Compression Properties of 2024-T86 Alloy Nominal Exposure Conditions Subsequent Compression Properties Total Actual Exposure Conditions Deformation Obtained0.2% offset Compression Temp. Time Deformation ----- Time Temp Stress -Loading Loading Creep Total Test Temp. Yield Strength Modulus *-.(hr) (%) Spec. No. (hr) (F) (psi) (Total) % (Plastic) % (%) (%) (F) (psi) (106 psi/in. /in.) 350 10 0.5 2E-T5 10.0 350 36,000 0.36 0.01 0.15 0.51 room 78,000 10.9 10 0.5 4L-T55 9.9 350 36,000 0.37 0.02 0.15 0.52 350 61,800 10.4 10 1.0 3H-T55 9.9 350 44,500 0.48 0.04 0.36 0.84 room 74,80010.7 10 1.0 4L-T2 10.1 350 44,500 0.47 0.03 0.48 0.95 350 58,800 10.3 10 2.0 2L-T2 10.2 350 47,000 0.50 0.03 1.07 1.57 room 73,000 10.6 10 2.0 3C-T5 9.9 350 47,000 0.53 0.06 1.47 2.00 35052,0009.9 50 0.5 4K-T5 5C,0 350 29,000 0.29 0 0.16 0.45 room 73,600 11.0 50 0.5 5C-TI 50.0 350 29,000 0.29 0 0.18 0.47 350 59,000 10.6 50 1.0 4E-T55 50.1 350 39,500 0.40 0.01 0.61 1.01 room 71,000 11.1 50 1.0 2A-T5 51.0 350 39,500 0.43 0.04 0.0. 0.96 35054,500 10.2 50 2.0 3C-TI1 50.1 350 41,500 0.47 0.06 0.49 1.06 room 69,600 10.8 50 2. 0 4L-T3 50.0 350 -I,500 0.46 0.05 0.50 1.06 35053,60010.1 100 0.5 3N-T2 103.0 350 28,000 0.22 0 0.23 0.45 room 73,10010.6 100 0.5 2N-TI 100.0 350 28,000 0.30 0 0. 19 0.49 35057,00010.1 100 1.0 3F-TII 100.4 350 37,500 0.40 0.01 0.57 0.97 room 68,50011.1 100 1.0 3C-Tl 100.0 350 37,500 0.38 0.01 0.66 1.04 350 52,8009.8 100 2.0 4F-TI 100.3 350 39,000 0.42 0.02 0.35 1.77 room 64,80011.0 100 2.0 5M-T4 350 39,000 0.40 0.02 0.51 0.91 400 10 0.5 3H-T1I 10.2 400 28,000 0.33 0.01 0.22 0.55 room 72,900 10.9 10 0.5 4L-TI 10.0 400 28,000 0.30 0.01 0.24 0.54 400 53,600 9.6 10 1.0 2H-T55 9.9 400 36,000 0.41 0.04 0.82 1.23 room 65,000 10.9 10 1.0 3C-T4 9.0 400 36,000 0.40 0.04 0.38 0.78 400 53,1009.9 10 2.0 4K-T55 10. 1 400 37,000 0.37 0.04 0.60 0.97 room 62,400 10.6 10 2.0 5G-T3 9.0 400 37,000 0.43 0.04 1.02 1.45 400 46,000 —-- 50 0.5 4E-T5 50. 1 400 23,000 0.25 0 0.30 0.55 room 62, 100 11.0 50 0.5 2A-T3 50.0 400 23,000 0.24 0 0. 30 0. 54 400 49,100 9.5 50 1.0 3B-T4 50.9 400 29,000 0.29 0.01 0.47 0.76 room 63,000 10.8 50 1.0 2A-T1I 50.0 400 29,000 0.30 0.01 0.67 0.97 400 47,100 9.8 50 2.0 3M-TI 50.0 400 31,500 0.34 0.02 1.20 1.54 room 56,100 10.4 50 2.0 5C-T4 50.0 400 31, 500 0.36 0.02 1. 20 1.56 400 45,200 9.5 100 0.5 4J-T2 100.2 400 21,000 0.24 0 0.42 0.66 room 60,200 10.7 100 0.5 3C-T55 100.0 400 21,000 0.24 0 0.33 0.57 400 45,600 9.7 100 1.0 2K-TI 100.4 400 27,000 0.28 0.01 1.07 1.35 room 62,500 11.1 100 1. 0 4L-T5 100.4 400 27,000 0.29 0.01 0.58 0.87 400 48,200 10.0 100 2.0 4D-T4 100.2 400 29,000 0. 32 0.01 1.86 2. 18 room 50,400 10.5 100 2.0 4F-T3 rupt. 87 400 29,000 0.29 0.01 1.87 at82hrs. -- —.. 500 10 0.5 4D-T2 10.2 500 14,500 0.19 0 0.41 0.60 room 45,000 11.2 10 0.5 5M-Tll 10.0 500 14,500 0. 19 0 0.46 0.65 500 31,300 8.8 10 1.0 2Q-T2 10.0 500 17,000 0.18 0. 43 0.61 room 43,000 11.0 10 1.0 3C-T3 10.0 500 17,000 0.21 0.35 0.56 500 30,7009.3 10 2.0 5M-TI 10.0 500 19,000 0.25 0 1.26 1.51 room 40,400 10.2 10 2.0 5C-T5 10.0 500 19,000 0.23 0 1.18 1. 41 500 28,600 9.6 50 0.5 3M-T5 50.2 500 11,000 0.20 0.06 0.56 0.76 room 36,100 10.7 50 1.0 2Q-TI 50.1 500 13,000 0.17 0 0.80 0.97 room 34,800 10,5 50 1.0 5G-T4 50.0 500 13,000 0. 16 0 1.44 1.60 500 19,000 —-- 50 3.0 2G-T2 50.0 500 15,000 0. 18 0 3.93 4.11 room 26,800 10.8 100 0.5 2L-T3 100.5 500 9,000 0. 12 0 0.63 0.75 room 38,500 10,7 100 0.5 3M-T1l 100.1 500 9,000 0.11 0 0.50 0.61 500 21,200 9,3 100 1.0 3H-TI 100.4 500 12,000 0. 14 0 1.94 2.08 room 31,000 10.7 100 1. 0 5G-T2 rupt. 75.9 500 12,000 0. 15 0 2.57 at 70 hrs. -- —.. 100 2.0 2A-T55 rupt. 99.3 500 12,500 0. 14 0 3.29 at 90 hrs. -- -- 100 2.0 5M-T3 100.0 500 12,500 0.16 0 1.27 1.43 500 21,8009.1 100 3.0 4K-TII rupt. 58.2 500 13,000 0.16 0 2. 12 at 48 hrs. -- ------ WADC TR 57-150 59

Table 21 Compression Yield Strength of 2024-T86 after Specified Exposure Expressed as Percentage of Unexposed Value at Test Temperature Exposure Temp. Exposure Time Total Def. Test Temp. Compression Yield Strength ( F) (hri) (%) (*F) (% of Unexposed Value) none none none room 75,200 psi none none none 350 66,9Z2 psi 350 0 none room 98.9% 0. 5 room 102. 9 1.0 room 101.0 2.0 room 90. 5 none 350 96.5 0.5 350 92.5 1.0 350 87.5 2.0 350 77.5 50 none room 95.4 0.5 room 97.5 1.0 room 93.8 2.0 room 83.8 none 350 96.6 0.5 350 88.4 1.0 350 81.6 2.0 350 ---- 100 none room 91.0 0. room 95.8 1.0 room 92.5 2.0 room 81.8 none 350 97.4 0.5 350 85.4 1.0 350 79. b 2.0 350-_ none one none roomn 75,'00 psi none none none -100 60,711 psi 400 10 none room 87.0% 0. 5 room 96.. 1.0 room 88. 1 2. 0 room -. none.100 95.5 0. 5 00 88. 5 1.0.00 83.0 2.0 400. —50 none room 79.1 0. 5 room 81. 4 1.0 room 82. % 2. 0 room.. none.00 85.b 0. 5 100 81. 9 1.0 400 78.0 A. 0 400 ---- 1 00 none room 73.9 0.5 room 79. 1.0 room 82.5 2.0 room 71.6 none 400 82. 5 0.5 400 79. 1 1.0 400 74.9 2.0 400... none none none room 75,200 psi none none none 500 50, 73-1 psi 50 0 10 none room 61.9% 0.5 room 59.2 1.0 room 56.5 2.0 room 51.9 none 500 71.0 0.5 500 62.8 1.0 500 58.3 2.0 500 52.0 50 none room 75.5 0.5 room 56.5 1.0 room 45.3 2.0 room 38.4 none 500 62. 3 100 none room 67.8 0.5 room 55.6 1.0 room 49.2 2.0 room 41.3 none 500 47.0 0.5 500 42.9 1. 0 500 42.4 2.0 500 43.3 WADC TR 57-150 60

Table 22 Effect of Unstressed Exposure on Room-Temperature Tension-Impact Properties of 2024-T86 Alloy Tension-Impact Properties (Smooth Bar) Exposure Exposure Energy Reduction Temp Time Absorbed Elongation of Area (~F) (hr) Spec. No. a)(ft - lb) (% - 2 inch) (%) Unexposed Average 18.2 5.8 11.2 350 10 4A-X3 15 3.0 7.9 10 3E-X22 21 5.0 9.9 Average 18 4.0 8.9 50 4M-X4 17 5.0 11.4 50 2C-X22 19 6.0 9.4 Average 18 5.5 10.4 1 00 3L-X4 10 6 0 8.5 100 2C-X4 16 6.0 6.1 Average 13 6.0 7.3 400 10 4M-X3 18 6.5 8.6 10 2J-X4 17 6.0 11.6 Average 17. 5 6.2 9. 1 50 4A-X4 11 8.0 13.0 50 3E-X33 21 6.5 7.7 Average 16.0 7.2 10. 3 100 2J-X22 18 9.0 12.7 100 4M-X33 19 7.5 9.2 Average 18.5 8.2 10.9 500 10 4G-X22 13 5.5 10.2 10 3E-X4 14 6.0 11.0 Average 13.5 5.8 10.6 50 4G-X4 11 4.0 11.5 50 2P-X33 14 4.5 9.2 Average 12.5 4.2 10.4 100 2P-X4 15 6.0 13.8 100 3L-X22 14 6.0 13.9 Average 14.5 6.0 13.8 a) Specimen gauge section 0. 200 inch wide x 0. 064 inch thick. WADC TR 57-150 61

Table 23 Effect of Unstressed Exposure on Elevated-Temperature Tension-Impact Properties of 2024-T86 Alloy Exposure Conditions Test Results Temp Time Test Temp Energy Absorbed (~F) (hrs) (~F) Spec. No. a) (ft - lb) 350 10 350 3J-X44 18 350 10 350 4M-X22 19 18.5 350 50 350 2N-X2 19 350 50 350 4H -X44 19 19 350 1 00 350 2E-X44 20 350 100 350 4M-X44 17 18. 5 400 10 400 2J-M4 20 400 10 400 3B-X44 19 19.5 400 50 400 2M-X2 20 400 50 400 3N-X44 16 18 400 100 400 3F-2 17 400 1 00 400 4D-X44 17 17 500 10 500 2P-X22 15 500 10 500 4P-X44 14 14. 5 500 50 500 2B-X2 14 500 50 500 3L-M4 13 13.5 500 100 500 3A-X44 12 500 100 500 4C-X2 13 12.5 a) Specimen Cross Section 0. 200 in. wide x 0. 064 in. thick. WADC TR 57-150 62

Table 24 Effect of Prior Creep Exposure on Room-Temperature Tension-Impact Strength of 2024-T86 Nominal Exposure Conditions Subsequent Total Actual Exposure Conditions Deformation Obtained Tension Temp. Time Deformation Time Temp Stress Loading Loading Creep Total Impact Strengths (~F) (hr), (%) Spec. No. (hr) (~F) (psi) (Total) % (Plastic) % (%) (%) a) (ft - lb. ) 350 10 0.5 3F-T4 10.0 350 36,000 0.36 0.01 0. 12 0.48 26 10 0.5 4J-TI 10.0 350 36,000 0.34 0.01 0.17 0.51 23 10 1.0 3Q-TI 10.0 350 44,500 0.48 0.03 0.60 1.08 22 10 1.0 Z2L-T4 10.2 350 44,500 0.46 0.03 0.62 1.08 22 10 2.0 3H-T4 10.2 350 17,000 0.51 0.04 0.95 1.46 24 10 2.0 2G-T11 10.0 350 t7,000 0.49 0.04 0.81 1.30 23 10 2.0 4F-T55 rupt. 7.2 350 47,000 0.55 0.04 1.44 at 4. 5 hrs. -- 50 0.5 5M-T55 50.3 350 29,000 0.36 0 0.16 0.52 20 50 1.0 2K-T4 50. 1 350 39,500 0.39 0.02 0.50 0.89 27 50 1.0 3P-T2 50.0 350 39,500 0.42 0.02 0.52 0.94 23 50 2.0 4L-T4 50.1 350 41,500 0.43 0.02 1.18 1.61 18 100 0.5 2K-T5 100.0 350 28,000 0.30 0 0.20 0.50 22 100 0.5 4D-T55 100.0 350 28,000 0.28 0 0. 18 0.46 20 100 1.0 2E-TI 100. 1 350 37,500 0.39 0.01 0.83 1.22 16 100 1.0 3P-T5 100.1 350 37,500 0.39 0.01 0.50 0.89 19 100 2.0 3H-T5 100.0 350 39,000 0.40 0.02 0.56 0.96 25 100 2.0 2N-T4 rupt. 97.5 350 39,000 0.41 0.02 1.81 at 96 hrs. 100 2.0 4K-T3 100.2 350 39,000 0.43 0.02 1.61 2.04 6 400 10 0.5 4D-T5 10.1 400 28,000 0.32 0.01 0.22 0.54 21 10 0.5 2G-T3 10.1 400 28,000 0.31 0.01 0.21 0.52 21 10 1.0 4J-T55 10.0 400 36,000 0.37 0.04 0.77 1.14 21 10 1.0 3M-T2 10.0 400 36,000 0.40 0.04 0.84 1.24 17 10 2.0 3M-T4 10.2 400 37,000 0.42 0.04 0.78 1.20 21 10 2.0 5C-T11 9.0 400 37,000 0.42 0.04 0.62 1.04 19 Note 2E-T5 rupt. 10.0 400 37,500 0.47 0.04 2.23 at 9.8 hrs. 50 0.5 3P-TIA 50.0 400 23,000 0.23 0 0.26 0.49 21 50 0.5 4F-T11 50.0 400 23,000 0.24 0 0.30 0.54 33 50 1.0 2K-T3 50.0 400 29,000 0.32 0.01 0.84 1.16 16 50 1.0 4J-T11 50.1 400 29,000 0.34 0.01 0.68 1.02 18 50 2.0 2N-T5 rupt. 43.0 400 31,500 0.36 0.92 at 24 hrs. -- 50 2.0 4K-TI rupt. 50.0 400 31,500 0.31 1.74 at 46 hrs. 100 0.5 2L-T1 100.0 400 21,000 0.24 0 0.36 0.60 17 100 0.5 4K-T4 100.3 400 21,000 0.21 0 0.31 0.52 21 100 1.0 4F-T5 100.2 400 27,000 0.30 0.01 0.79 1.09 13 100 1.0 3P-T1 100.1 400 27,000 0.29 0.01 0.62 0.91 17 100 2.0 2K-T55 100.0 400 29,000 0.31 0.01 1.03 1.34 16 100 2.0 3M-T3 100.1 400 29,000 0.33 0.01 1.23 1.56 18 500 10 0.5 3P-T3 10. 1 500 14,500 U. 15 0 0.36 0.51 17 10 0.5 2G-T55 10.1 500 14,500 0.14 0 0.35 0.49 17 10 1.0 4B-T4 10.0 500 17,000 0.21 0 0.51 0.72 18 10 1.0 2G-5 10.0 500 17,000 0.20 0 0.56 0.76 18 10 2.0 5G-T55 10.0 500 19,000 0.22 0 0.80 1.02 14 50 0.5 5M-T5 50.0 500 11,000 0.12 0 0.57 0.69 15 50 1.0 4J-T5 50.0 500 13,000 0.15 0 3.35* 3.50* 16 50 1.0 3C-T2 50.0 500 13,000 0.16 0 0.90 1.06 16 50 3.0 4N-T1 rupt. 32.2 500 15,000 0. 16 0 2.74 at 29 hrs. 100 0.5 4E-T4 100.0 500 9,000 0.10 0 0.66 0.76 19 100 0.5 3M-T55 100.1 500 9,000 0.09 0 0.49 0.58 13 100 1.0 2E-T4 100.2 500 12,000 0.14 0 1.86 2.00 18 100 1.0 3Q-T11 100.2 500 12,000 0.14 0 1.28 1.42 16 100 2.0 5C-T3 100.0 500 12,500 0.17 0 2.54 2.71 12 100 3.0 2G-T1 rupt. 84.0 500 13,000 0.16 0 3.88 at 83.5 hrs. -- a) Specimen Cross Section 0. 200 in. wide x 0. 064 in. thick. * Estimated WADC TR 57-15063

SHEET 2 SHEET 3 SHEET 4 PANEL NO. RR __________. A R R R 8 ___ R R C R | R D R Q R E R R R F T Q T R E__________R R_________R R a0 _. R R J R R R K __________Q R L R R Q M R R R N [q _ <R TRR R P 0 20 SHEET SAMPLING SCHEME 2024-T86 SCALEA........ I NCHES TI IC I | T I T TENSILE C2 X22 |M22 I X2 I T2 |M2 C COMPRESSION X 33 33 T3 C31 X3 M TENSION-IMPACT M44 | T4 X44 M4 X4 4 X EXTRA T5 I M5 X5 PANEL SAMPLING SCHEME Q TlIl |XI | TI ALL BLANKS X22- T2| X2 I INCH WIDE X33 | T3 I X 3 X44 \ T4 ] X4 T55! X 5 I 5 PANEL SAMPLING SCHEME R 0 10 SHEET SIZE 48 72..065-lNCHES SCALE......... PANEL SIZE 48" 5-5-1/2 INCHES INCHES SAMPLE CODE -(EXAMPLE) 4CT2,1.E.,SHEET 4- LENGTH ONLY PANELC -TENSILE SPEC, NO.2 Figure 1 - Sampling Procedure for Sheets of 2024-T86 Aluminum Alloy. WADC TR 57-150

A B| C |D EF G H J K L | M N P a R S T |U - -PANEL NO. 1 1W 1 1| W Y | 1Y IZ- | |1W SHEET I I Iw | _.. _. SHEET 2 __ __ __ SHEET 3 Sheet Dimensions: 36 x 120 x 0. 064 inches Panel Width: 6-1/4 to 6-1/2 inches Sheet Designation: 1, 2, 3, etc. Panel Designation: A, B, C, etc. Panel Location Code: 1A, 3L, etc. (Sheet No. - Panel No.) Specimen Blank Sampling Scheme: W, Y, or Z (see Figure 3) Figure 2* - Panel Sampling Scheme for Sheets of 17-7PH Stainless Steel Sheet WADC TR 57-150 65

XI Ml| T M2 C22 TZ C2 X33 3 X3 C441. T4 JC4 1 | M4 Y S _ MS YG 7T5 M5 | Y5 y66 |C6 I M6 I YC JiV r w xi T( X22 T2 |X2 X33 T3 - 3 x 44 T4 X4 T5 I 5 T6 | 6 XI | T21 - X22 T22 X2 X33 T23 X3 X44 T24 | X4 T25 | y y6C | T26 -- 0 10 SCALE:,........ INCHES T - TENSILE (LENGTH ONLY) C - COMPRESSION ALL BLANKS I INCH WIDE M - TENSION-IMPACT X - EXTRA Figure 3. - Specimen Blank Sampling Schemes for Panels of 17-7PH Stainless Steel Sheet WADC TR 57-150 66

Exposure Spec. 0.530 _ o 003) H J Tensile Spec. 0. 500 (+ 0 0 ^ <-~15 /1( ------- 4. 8 __________ lip15/l1 rind last 1/32 each edge, Grind- longitudinally - 5/32 D 3/8 D 22 Tensile or Creep-Exposure Specimen ___________ ~ ]R 0. 200 _______ ---------- \^^~ < ~+0. 003).~T.1-1/4 3/4 2 3/4 1-1/4 ^__________________________6 _______________________________ Tension-Impact Specimen DO NOT SCALE 0. 500 ALL SPECIMENS ALL DIMENSIONS IN INCHES (+ 0. 003) FULL SHEET THICKNESS 2-3/4 ~ -f-0. 064 INCHES L _____ 2-3/4 ____ Compression Specimen Figure 4. - Details of Test Specimens (Tension-Impact and Compression Specimens Designed to be Cut from Creep Specimens after Exposure).

All Dimensions in Inches. R R - 1 /o full sheet thickness -.064 inches Figure 5. - Design of notched tension-impact specimen WADC TR 57-150 68 ~ _______ _____ _ —--------— o

Specimen \ Speie Translucent Scale / Spec imeFluorescent Light, Inside / / / ^ S Observer Extensometer Cross Hair Bar —-— / Telescope uC-S Mirror Similar set of Bars on front of Specimen Figure 6. - Simplified Drawing of Modified Martens Extensometer System Used for Deformation Measurement in Creep Tests. WADC TR 57-150 69

:- -:::-::: E.::::::::::::::::-:::.:.:::.'::::::::.': f::::::.::.';: S-:-:.:':-:.:::::::::-i::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::'::: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ -:lllrl-l-rr-i —il:::::.::::::::E.:. i:::::::::.i:.:::::B s:::. >: rs::s~~~~s::::::s:-s:::::s::::: s::: s::::::::::._::::::B a........................................................::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::-:::: *'::-''-'::-_' — - I: 11[: —:::- s_-:':' *:'t -:ii-iDi i-i;"i — _ i:.'S t: 0:.'. -:- t:: -:": ~~~~~~~~~~~~~~~~~:::: 11: v v,,:::': _,:;,,,,~~'-i.:_ -.,,, j 0 0:;:: -:: ti:; i.::0-0fff:::E-E0.t:-0:; 0 f i:0. id-;: ti:00 f)000:::00 00::00S':-:-:-:::-::::::::-::::-::;: Figure 7. - Corrponents of Compression Fixture - Note the Off-set Grooves in Guide Blocks. WADC TR 57-150 70

F~~~~~~~~~iiiiiiigr8.CmrsioFixue A sble dfrTsinwithAeaingiiiiii Extensometer ~~~~~~~~jiin lace.iiiiiljjiiiiijj WADC T R ~~i:~i~ii~:~i: 5 7 -' —~ii —150. 71jj~jjj~jjj:iiiiiii

4: ~ ~ ~ ~ i x~~~~ " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~" * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.4j4.xK~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......... ~~f4ME Figure Original Rod and Tube Extensometer Fixture with 0 S Peters Microformer Strain Follower Attached WADC TR 57 150 72~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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'Siiiiiiiii^^ii-ili~;~o ~;i~i-;:i: Figure 11. - Tension-Impact Specimen and Gripping Assembly for Smooth Specimens. The Plates at Far Left Fit Over the Impact Machine Pendulum Head, WADC T1R 57-150 7.....................74..............:-iiiiiii: i i i i- i i i ii;:;;~:: — ~:'iiii'''~':'i'':'''............. ~ ~ ~ ~ a~~:a;;"":_~iiiiiiiiii,.............ii ii ii ii ii ii ii............ i ii ii ii ii ii ii i............:::::. I::':::I..........~..............~:iii'i i~ii ii....................~::............~~~~~~~:.............~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-............~~~~~~~~~~~~~~~~~~~~~~~~............................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:.............~g~I~~gB........................................................................:~~ii~ji Figure I 110 Tension-Impact Specimen and Gripping Assembly forii~i::ii~i SmothSpcien. hePlte a Fr ef Ft ve Figure the Impact MIm achine Piendulum Head. sse blyfo

INDICATOR AND / SCALE / / EXISTING BASE OF IMPACT MACHINE ADDED STRIKING PLATES AND SUPPORTS Figure 12. - Geometry of Olsen Impact Machine as Modified for Tension-Impact Testing WADC TR 57-150 75

C U> H Ug SCALE UNITS, AL+AR, MEASURED OVER THIS LENGTH? EFFECTIVE GAGE LENGTH SHANK FILLET GAGE SECTION. -- 0~~ ^.~_______^__________^ Vi I' RADIUS SHOULDER TO SHOULDER, SS:3.55* PIN TO PIN. PP:4.82" Figure 13. - Gage Section of Typical Strip Specimen for Illustration of Calculation of Effective Gage Length

175 09 1~~~~~~~~~~~~~~~~.0 600 ~F 0U 150 0 125 100 0 800"F 0 900 OF 50 25.01 0.1 1.0 10.0 100.0 Creep rate - scale units (AL + AR)/hour at 25% of rupture life Figure 14. - Stress Versus Relative Creep Rate at 600~, 800~, 900~F for 17-7PH Alloy in TH 1050 Condition

180 (4.0) C)170 9 ( 170 -9) 600 F Rupture (16.5) 160 U-1 c ode 01 t^ ~150 0 rupture time 2 7 1 ( ) elongation at rupture 1 % /0 3 * 0.5% 600~F Total Deformation 140 1- % x 2 % Total Deformation + 3% J 130 120 to 0 o 110 (22) 800~F Rupture -0 100 4)~~~~~~~~~~~~~~~~~~~~~~~(3 70 — *^^~ A AA Xi~^~^ (370 50 90 0. 5 l/o 3 76o 80 ^ ^ 800F Total Deformation 1% 8 2~ o-., 80 x + ~~~~~(31) (29. 1) 3.5 70 ~~~~~~~~~~~~~~~~~~~~~~~~900'F R upture (29. 8)(33,2 60 (33 )Oi3 (43) 50 900F Total Deformation o0.5% 40 0.1 1.0 10.0 100.0 100.0.0 Time - hours Figure 15. - Time for Rupture and Specified Total Deformations Versus Stress for 17-7PH Alloy in TH 1050 Condition

0~ Rptre40 ^(4,5) Rupture 350 F H1 2~ (2.8) 30 0 Rupture (4. 0) 30 ( )Elongationat rupture R uptur 00. 5% 6 23~~~~~~ ~~~~~0~ ~ ~ ~ - 10 20 30 (7. 0) 500). R uptur e Figure 16 - Stress Versus Time for Rupture and Specified Total Deformations for 2024-T86 Aluminum Alloy at 350, 400, 5000F. (Original Survey Data ).

I I I I I I I I I I I I I l II I III > 110 0 - 10030 ORRuuptu re 90 80 00 0.1 1.0 10.0 100.0 1000.0 oime - hours 60 50 40 Solid Lines - Data of Hanlon, Salvaggi, Guarnieri (ref 8) 0.5% 30 O Rupture 00. 5 %o 1o% Total Deformation University of Michigan Data Points 20 + Jz% 10 0. 1 1.0 10.0 100.0 1000.0 Time - hours Figure 17. - Comparison of University of Michigan Data Points with Rupture and Total Deformation Curves of Hanlon, Et Al for 17-7PH at 800-F

80 o 70 * mp r Compression Yield 70 o ~' ^ssss ~ \s. \ Ultimate C,' \s s Tensile \ Ej Tensile \ Strength, 0 V Yield c 60 50 *Tensile Elongation 10 ~ 40 d- 0) O O E'- W 0 100 200 300 400 500 Test Temperature - ~F bo V 20 Smooth Tension-Impact Strength'-4 0'A4 - e d T8 m A 10 0Notched Tension-Impact Strength g~j3~ Elongation (Smooth Tension-Impact) Test Temperature - tF Figure 18* - Effect of Temperature on Short-Time Properties of A-Rcie204T6AuWADC TR 57-150 81 WADC TR 57-150 81

Room Temperature (75~F). / o 50 1~/ _^ 350~F r L / /, f 400 F 40 / // 500'F 30 — 0 001 20 Strain - inches per inch Figure 19, - Representative Tensile Test Stress-Strain Curves for As Received 2024-T86 WADC TR 57-150 82

80 Room Temperature (750F) 70 ~ 400 ~F 60 0 / 350~F 20 10 0 | X 50* —.001 * 0 Strain - inches per inch Figure 20. - Representative Compression Test Stress-Strain Curves for As Received 2024-T86 WADC TR 57-150 83

100 Hours s 10 Ho Exposure at 3500F Exposure Exposure Stress Creep Total Stress Creep Total Code Spec. No. (pi) De., Def., C de Spec. No. (psi) el., De., A 3E-T2 Unexposed --- -- A 3E-T2 Unexposed --- -B 2P-T Zero -- B 2P-T3 Zero -- -- C 2F-T55 14,500 0.30 0.47 C 2M-T5 28,000 0.24 0.53 D 4N-T5 17,000 0.89 1.09 D 2H-T1 37,500 0.70 1.11 E 2D-T3 19,000 approx. 3 80 E 3K-T5 39,000 1.52 1.95 80 70 70 60 60 o 50 50 S40A 7 40 / 50 Hour4 Expo0ure t 400-F ======= —'i — --- --- Expoaure at 4 OO*F Stre Creep Total EoA B C -- Code Spec. No. (hr) (pi) Df. % Def., % A 3E-T2 Unexpo30ed --- - 20 2 0 10 10 -E0 29,2 Strain - inches per inch Strain - inches per inch 50 Hours Exposure at 400'F T ~em~pouerature for 2024-T86Alloyafter Exposure at 400*F Exposure Stress Creep Total Exposure C ode Spec. No. (psi) Del., % DeS., % Time Stress Creep Total Code Spec. No. (hrs) (psi) Del. 9. Def. 9. A 3E-T2 Unexposed.... B 4M-T2 Zero --- --- A 3EoT2 Unexposed.. C 4H-T1 23.000 029 0.53 B 4GoTI 10 Zero G 4H-T3 100 27,000 0,78 1.07 0 37K-TS 29.000 0. 6 2 0.96 C 3D-TI l lO 3,6.070.40 -A B C D E A B D ~~~30~~~~/ -60 E 2MoT4 31,500 1.020 o F /.001 3T S 0. 001 ~0 O ~,- ~ 2CIT 10I0 Zer -- Strain - inches per inch Strain - inches per inch Figure 21. - Representative Stress-Strain Curves in Tension at Room Temperature for 2024-T86 Alloy after Exposure to Various Amounts of Prior Creep at 350', 4000, or 500F WADC TR 57-150 84

100 Hours Exposure at 350~F Exposure Stress Creep Total Code Spec. No. (psi) Def., Def., % A 3A-TI Unexposed.. B 4P-TI1 Zero - C 3H-T3 28,000 0.19 0.46 10 Hours Exposure at 5Q D 3B-T3 37,500 0.68 1.07 Exposure Creep Total Stress Creep Total 80. E 2NT3 39.000 2.04 2.44 Code Spec. No. psi Def., % Def., % A 3B-T1 Unexposed --- --- B 2D-T2 Zero -- - t' 70 * C 1B-T5 0.40 0.63 D 2N-T2 0.57 0.79 E iL-TII 2.67 2.93 *0 *,0 i 1 2 50 30 A B D E 30 Strain - inches per inch Strain - inches per inch 50 Hours Exposure at 400*F Exposure Stress Creep Total Code Spec. No. (p) Def. Def.,% Expo ure t 400F A ZF-T5 Unexposed --. — Expoeure B 3N-T3 Zero. — - Time Strese Creep Total C 2E-Tll 23,000 0, 34 0.59 Code Spec. No. (hro) (i Dt. S Def..W D 4N-T3 29000 1.03 1. 36 so E 5C-T2 31,500 1.34 1.64 A 4N-T2 Unexposed so 80 3A-T55 10 Zero C 2H-T5 10 36,000 0.73 1.15 D 2D-T1 50 Zero E 4N-T3 50 29,000 1 03 1.36 to~~~~~~70 *~ ~70 F 4E-TI 100 Zero. - --- G 3F-T2 100 27,000 0.98 1.28 60 60 S 0 40 -' 40' Zero A / B / C /D/ E. / B/ / D/ / 2T0 20 610 10 -..oo.-01 Strain - inches per inch Strin - inches per inch Figure 22. - Representative Stress-Strain Curves in Tension at 350*, 400~, or 500~F after Prior Exposure to Various Amounts of Creep at the Same Temperature WADC TR 57-150 85

Exposure and Test Temperature Tensile Strength 60 - 350'F 80 Room-Temperature' ~ Tensile Strength o A 400-F Exposure o A Temperature:-" —-'"''-)-O —- - - - 3500~F 50 s. 20 30 40 50 60 70 80 90 100 10 0 3 10 50 65 0 800 90 r10 Exposure Time - Hours Exposure Time - Hours 70 i Yield Strength O 70 oI~~~ Ir~~~ \; i u-~~~~~^ 8~40 F 50 500 F 40 N Xote: Each point is average of two \ 00~F ^ - 500-F tests,,' Yield Strength 500F 30 3 [,5 I I'I Io 0 10 220 30 40 50 60 70 80 90 100 i'1,- ~ ~ ~ ~ ~ ~ ~ ~ ~ 1 20 30 40 50 60 70 80 90 100 Exposure Time - hoursxposure Ti Hours Exposure Time - Hours E:<posus-c TRoom-Tenemperature 350~F 60 0 350'F A 400()~F Elo 500F Elo 400ation i S Room Temperature Tn st Test at Exposure Temperature 10,.' oY~ ~ ~ ~ ~~~~~~~~ o o50 o 50 o 0 10 20 30 40 50 0 7 0 90 10 0 10 0 30 40 50 6 70 8 90 100 ote: Eacposure Time -s a e of two Figure 23. - Effect of Prior Unstressed Exposures of 204-T86 on Tensile Propertie llrYield Strength f 30 30 0 10 20 30 40 50 70 80 90 100 fL - Exposure Time - hours 7.xposure Timne - Hours Exposure Temrnpe ratu ret 0 350'F A 400OF at Room Temperature at re Tempeure at e Temperature WADC TR 57-150 86

s0o 350'F Exposure 8 00 EpJr 1 60 6x0 * o 0;5 * - l l * 0 * 1'.^ * --.o6 - *lo 0 p osure 60060 a0 0.5 1,0 15 Z.0 0 0.5 1.0 1.5 2.0 Creep Deformation - % Total Deformation - % 80 80 &1 400F Exposure 400-F Exposure o, 0 -4 1 o 60..I..I. lpI..7 IaaIa_____________0 _ _AI. _ 7I A_ I a ~, 70- - i --- -O 10 hra X 70 ~ —- u,_10 hro t= 50 hrs O.00 c I, ~, t 670,. I.... I ~ 100.Ir I O 100 i hrr I ~0 ~ 0.5 1.0 1.5 2.0 00 0.5 1.0 1.5 2.0 Creep Deformation - %Total Deformation - Total Deformation - % 60 -6 50 -. — 0o_-O- 10 hrs.41O-hru Creep 500*F Exposure 50o Ep00- Exposure E o o o 3 10 Temperature 30 -- -— o -- - - 2- o5. 40 0 4r 40 1 0 0 hr s Creop Deformation - % Total Defor0mation - % Figure Z4. 5- Room-Temperature Tensile Strength of 2024-T86 Alloy after Prior Creep at 350, 400, o 30.Temperature 30 0 0. 1.0 4.0 5.0 Creep Deformation - * Total Deformation - % Figure 24. -O Room-Temperature Tensile Strength of 2024-T86 Alloy after Prior Creep at 350, 4000, or 5000F

^>a~~~~~~~~~~~ ~350'F Exposure 0 -. ~~~70 J 0 a'^ -- -- ---- -As10 hra e d 350 F Exposure h-1 ~ A ~ As Received 0 0..... 00510159 Hj. 7 70 60.- hrI o C 10 hkw 60 100 hr0 U1 A __LnU 60 I 100I 1_ -— _____-__ -____________________ 100kwI\.____ ly ~ ~.ra 5 r 0 ~~0.5 1. 1.5 2.0 0 0.5 1.0 1.5.0 Creep Deformation - Total Deformation 70 400IF F ~~~~~70 ~400'~F Exposure~ 70400'F Exposure 0.~~~~~~~ \ ~ ~ ~ ~ ~' 50* Exposur ~ Y\\u 60 0 10 hkw, Creep Exposure 0 0 l0hws 0'60 0 0h 34 5~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~$ 50 hrs UA 505 h 00 50h20 00 50 A 100 s 100 hr. 0 1.010 12.5 23. 4. 0 0.05 1.0 1.35 2.0 Creep Deformation - Total Deformation -5 500-F Exposure 505 0i0r 2, - R oTemperature 0 500~F Exposure Ui, R 40 40 - -10 hrs o h 34 Z AA30 to A33 50 hr. 0 050kwre A 0 ~-~1 —- 100 hr. 100 hrs 20 0 20 0 1.0 2.0 3. 0 4.0 0 1.0 2. 0 3. 0 4.0 5.0 Creep Deformation -, % Total Deformation - Figure Z5. - Room-Temperature Tension Yield Strength of 2024-T86 Alloy after Prior Creep at 350, 400, or 500-F

60 X, 60 S^ 350*F Tensile Strength ^ I> o *R _ _ e g —p, 60 1350F Yield Strength 0 @ so ~ t-XT —-- -0-l~.. =.G.IO....-1 50 hr. --' " o*1.5 1. (1 1,.5 2,0 (I ()' b 1.0 h.. r.( 0 100 hrs so ~~~~~~~~~~s V}~~~~~~~~~~~r —— ^~~~~~~~~~~~~~~~~~~~~~~~~~ O0 hrs 00.5.010 0.5 1.0 1.5 200 Creep Deformation - % C reep Deformation - % 40 IO~~~~~~~~~~~~i5 4\00*F Tensileld Strength 400*F Tensile Strength - - -- 2 - | - 0o hr r, 10 hrs''0 100 hr1 00 4~ |-2a - ^ - 50 - A\ n ___ --- 50and 100 hrs, Z!! I n. L.,,.. 1.' I''0'' I. 0 1.0 1. 3.0 4. 0 0. 1.0 2.0 3.0 4.0 Z. Creep Deformation - % Creep Deformation - % Figure 26, - Tensile Strength 500Prior Yield Strength o 30 m 10 hrs 10 hrs ~ " 20 -tr 0 ~' ~-' —-'""' —---- 50 and 100 hrs 5 0 10 j,,...,. I, I,,10 I I I Creep Deformation - Creep Deformation - Figure 26. Tensile Strength and Tension Yield Strength of 2024-T86 Alloy at Exposure Temperature alter Prior Creep for 10, 50, or 100 Hours at 350', 400', or 500F

10 hrs PQ 80 O -, -P -A _Orf_ 50 and 100 hrs U 75 r0 Q |350-F Exposure ~ 70...... 0 0.5 1. 0 1.5 Creep Deformation - % 80 0 400 ~F Exposure X 65.. 0 0.5 1.0 1.5 Creep Deformation - % 70 65 4 500 F Exposure _- VS 0o 0 10 hrs T_4 -. - 6 t-5 \ n- __ 50 hrs x b \ 0 35 f- ^~_________________________ 100 hrs 30 - 0 25, I t 0 1.0 2.0 3.0 4.0 Creep Deformation - % Figure 27. - Effect of Prior Creep Deformation for 10, 50, or 100 Hours at 350~, 400~, or 500~F on the Rockwell "B" Hardness of 2024-T86 Aluminum Alloy WADC TR 57-150 90

0 10 H g 0 ~~~~~~~~~I.~~~~~~~~~~~~~~b vj J0 Tests at Room Temperature 43~~~" ~ 0 0.15 1.0 1.5 2.0 Creep Deformation - % Code Creep Period, hours r^~ ~~~~~~ ~~~0 10 A o50 10 0 100 9: 20_9 0 ~ Tests at 350-F 0 0 0.5 1.0 1. 5 2.0 Creep Deformation - F igure 28. - Elongation of 2024-T86 in Tensile Tests at Room Temperature and at 350'F after Prior Creep at 350F for 10, 50, or 100 Hours.

Tensile Strength 240 ~~~~_240 -900~F 220 600"F 200 180 160 140 Hardness 50 100 900 ~F 16~~~ ~~~~~0 r 4600 5F 80 60 40 Elongation o 40 600 10 - 800oF 900 ~F | _0 _ _ _ _ _ _ _ _ _ _ _ ___ 0 0 10 20 30 40 50 60 70 80 90 i00 Exposure Time - hours Figure 29. - Effect of Unstressed Exposure at Indicated Conditions on Tensile Strength, Elongation, and Hardness of 17-7PH Alloy in TH 1050 Condition WADC TR 57L150 92

170 0 Stress for 2% Deformation 160 \ at 600~, 800~, 900~F - from Figure 15 150 140.~^~~~~~ 140 t~~-*- \Estimated Stress for 2% Deformation in 100 hrs. 133 t \ at Intermediate Temperatures o \\ of 650~, 700~, 750~, and 800~F. c 120 ~ 110 100 0 90 - c 80 U S 70 ~ 60 ~ \ ol2% - 10 hrs.'~'t~~ \e8n~~ ^ 2% - 50 hrs. 4J 50 2% - 100 hrs. 40 30 20 10 0 100 200 300 400 500 600 700 800 900 1000 Temperature - ~F Figure 30. - Stress for 2% Total Deformation in Various Time Periods Versus Test Temperature for 17-7PH Alloy (TH 1050 Condition) WADC TR 57-150 93

250 Tensile Strength 240 o A A 230 |f 220 ~ 21 Average of 210 2z10: 3 sheets 200 0 O 190 I I 4.4 230 o Yield Strength A,: (0.2% offset) o 220/ 4 Q 210 -A 4 —,, Z 1 Code - A verage of - / Zero stress for 200 3 sheets 10 hrs o 53 -- A —2% nominal total o a- 9 deformation in 190 0 100 hrs 0 180 I I —-— I I I -- I I I'I I I i 10 -Average of Elongation 1 3 sheets 0]' —'' 1 ^ I II I i,: _ 50 Hardness Average of 3 sheets A U I; 40 4,,, 0 100 200 300 400 500 600 700 800 900 1000 Exposure Temperature - *F Figure 31. - Effects of 100 Hours Unstressed Exposure or 100 Hours Stressed Exposure to 2% Total Deformation at Indicated Temperatures on Room Temperature Tensile Properties of 17-7PH Alloy (TH 1050 Condition). WADC TR 57-150 94

0 LD Plastic Loading Deformation 0 0 LD = Total Loading \ Deformation \ TD = Total Deformation \0 "20 at end of 100 hrs. 0 \DT \ TD i O \ H 10- -10 LD p \ LD LDT I I I J'. I I I,I 0 0 100 200 300 400 500 600 700 800 900 1000 1100 Test Temperature - ~F Figure 32. - Proportion of Total Loading Deformation or Plastic Loading Deformation to Total Deformation for 17-7PH (TH 1050) Stressed to Z% Nomrinal Total Deformation in 100 Hours at Indicated Temperature. WADC TR 57-150 95

10 Hours Exposure at S00o Exposure Stress Creep Total 100 Hours at 350'F Code Spec. No. (psi) De. Del o Exposure A 2C.C3 Unexposed.... Stress Creep Total B 2.X2 Zero Code Spec.No. (psi) Del..% Del.. C 4D-T2 14500 0.41 060 A 2C-C3 Unexposed --- _ 0D 5M-T1 19,000 1.26 1.51 B 2J-X44 Zero -- -- C 3N-T2 28,00 0. 23 045 D 3F-T11 37,500 0;57 097 E 4F-T1 39,000 1.35 1.77 80 80 70 70 60 60 2so 5 so o5 j / / / D E A B C D ~o10o 120 0 Strain - inches per inch Strain-inches per inches Exposure at 400*F 50 Hours Exposure at 400*F Exposure Exposure Time Stress Creep Total Stress Creep Total Code Spec. No. (hrs) (psi) Def., % Def., % Code Spec. No. (psi) Def., % Def., A C3 Une A'ZC-C3 Unexposed A 2C-C3 Unexposed -- --- B 3L-X33 10 Zero --- - B 4G-X2 Zero --- --- C 2H-T55 10 36,000 0,82 1.23 C 4E-T5 23,000 0.30 0.55 D 2P-X44 50 Zero --- - D 3B-T4 29,000 0.47 0.76 E 3B.T4 50 29,000 0.47 0 76 E 3M-T1 31,500 1.20 1.54 F 4A-X33 100 Zero -- - G 2K-T1 100 27,000 1.07 1.35 80 80 70 70 60 60 A B C D E 40 40 A B / D E F/C 30 30 20 20 10 10 0 0 Strain inrhes per inch Strain - inches per inch Figure 33, - Representative Stress-Strain Curves in Compression at Room Temperature for 2024-T86 Alloy after Exposure to Various Amounts of Prior Creep at 3504, 400, or 500F WADC TR 57-150 96

100 Hours Exposure at 350'F Exposure 10 Hours Exposure at 500'F Strenrth Creep Total Code Spec. No. (pi Def., % Def. Exposure Stress Creep Total A 2M-X Unexposed. Code Spec. N. (pi) De.,, % Def., B 3J-X1 Zero. C 2A-T1 28,000 0.19 0.49 A 3G-X5 Unexposed 80 D 3C-T1 37,500 0.66 1.04 8 B 2B-XI Zero C 5M-T11 14,500 0.46 0.65 D 5C-T5 19,000 1.18 1.41 70 70 60 a60 S so 50 A B C D 40 40 30 30 AA 3J-X- -- A 3J-XD 20 20 10 10./ / / / -oo-.6o k /.^ 60 X ~~- oL~ —- I <0 - w 30 y. 0 0 1 Strain - inches per inch Strain - inches per inch 50 Hours Exposure at 400VF 400AF Exposure Exposure Exposure Code Spec. No. Stress Creep Total Time Stress Creep Total (psi) Del., % Del., Code Spec. No. (hrs) (psi) Del., 5Def., % A 33-X5 Unexposed.A. 3J-X5 Unexposed.. S 4N-XS Zero - B 4E-X5 10 Zero C 2A-T3 23,000 0.30 0,54 C 3C-T4 10 36,000 0.38 0.78 D 2A-TI 29,000 0,67 O.97 D 3PoXI 50 Zero.. E 5C-T4 31,500 1.20 1.56 E 2A-TII 50 29,000 0.67 0.97 80 8 so F 2N-I 100 Zero.. G 4L-T5 100 27,000 0. 58 0.87 70 - 70 60 - 60 o 50 s50 o a 40 -40 B C D E k 30 30 A B D E F 20 20 10 10 001.0 4.0 0 Strain. inches per inch Strain - inches per inch Figure 34. - Representative on Stress-Strain Curves in Compression at 350, 400', or 500~F after Prior Exposure to Various Amounts of Creep at the Same Temperature WADC TR 57-150 97

80 *a m ^ - Expos ure o I^\ ^ — n Temperature.,~~~~~: |~~~\\~ \o~ ^3500F ^h \ ^^ ^^^^^ 40 0 60 -r-I I~~~I A 400FO 0 c) I | o 5000F 5 50 0 1f U 40 30 J 0 10 20 30 40 50 60 70 80 90 100 Exposure Time - Hours Figure 35. Effect of Unstressed Exposure on Room-Temperature Compression Yield Strength (0. 2% offset) of 2024-T86 Alloy WADC TR 57-150 98

rF-As Produced - Room Temperature Strength 70 Exposure and Test Temperature 350~F 60 400~F 50 |) 50 \ 2 —---- - 400-F ro \ 0 40 \ c i 0 30 0 o0, 5500~F 0 20 - - - -- - - a ~ I i | 0 10 20 30 40 50 60 70 80 90 100 Time - Hours Figure 36. - Effect of Unstressed Exposure on Elevated Temperature Compression Yield Strength (0. 2% offset) of 2024-T86 Alloy. WADC TR 57-150 99

-4 r80 350'F Exposure ^ ^* ~~ ~ ~ ~~~~~0- 0 Ml ~ /^ ^~^^*~ 350'F Exposure 0 0~~~~~~~~~~~~~~~~~~7 * S~~~~~~~~~~~~~ CO S 107:0 hr.70 10 hrs 70 10 hrs!5' ^ ^ ^ -". lOah rsw 50 5 0 h ro U1 100 hra 100 hre 1~~~~~~~~~~~~~~~~~~~~~~00 hts 60 60 0.5 1.0 1.5 2.00 0.5 I. 0 1. 5 2.0 U1 Creep Deformation - Total Deformation - % 0 70 400'F Exposure 70 400F Expoure 0 / / 0 hrs 0 Pt \Q10 hrs 0 r 60 60 * 60 S I. (-1 I' 50 hrs P 50 hrs O~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~C 0 50 100 hrs50.... I.... 1.... i.... I~_i - * -. -, — I - i-.- i- i- | - i -- i- i.... I.-. -, I 100 hrs 0~-.5 1.0 1.5 2. 0 0.5 1.0 1. 5 2.0 Creep Deformation - o Total Deformation -% 60 60 500 F Exposure 50 50 500-F Creep o Exposure S.%~~~~~ T^^.SI~~~~~~~~ 40R~~~~~~'I~~ ^~ ^~4 10 hr. 040 10 hrs k6 o (t S ^^"^s^^^^^30 -^^^\'^-l''^^3 100 hr. S 30 10 h^Oru ^^ ^50 hrs 50 hrs 20 20 -.... 2 0 -1.0 2.0 3.0 4.0 5. 0 6.0 0 0.5 1.0 1.5 2.0 Creep Deformation - %Total Deformation - % Figure 37. - Compression Yield Strength of 2024-T86 Alloy at Room Temperature after Prior Creep for 10, 50, or 100 Hours at 350', 4000, or 500-F

70 &>b~~~~~~'Szt~ V^^-^ ~ ^^^^^^<3^o 350'F Yield Strength e < 60 3507F Yield Strength 2 60 I- ~ ~ ~ ~ U 1 5 ~p 50hr6 -rs 4 4) E ^ 100hrs 10 hrs s 4 - ~ 100rU) 0 hr 5 10hrs U) 50 D -0hs ". I i^_.0Jr50 L J. f.. * *. *.*r 0 0.5 1.0 1.5 2.05.5 2. 0 — 3 Creep Deformation - % Tot.l;forrrrsti r. -% (1 0 60 60 \ 4 60 -55 4005F Yield Strength 0. v ^ - 0 0 - 0 55 o~~~~~~~~~~~~~~~ o NI n10r 4005F Yield Strength 50 * -10 hrs 45 hr'4 4., 0I hrs.50 r 0 - ~ 0.5 1.0 1.5 2.0 _ _ ~., M ~~~~~~~~~~~~~~Total Deformatio n - %' Creep Deformation -Total Deformatio 0 40. 30 10 hr. 500FF'Yield Strength -8 A at 100 hre 30 200*20 10 hrs 0 0 0: 00 hrr 5 5000F Yield Strength 20 \50 bra*10 ~-.olhrs 20 10 0 1.0 2. 0 3.0 4.0 0 0. 5 1. 0 1. 5 2. 0 Total Deformation - j Creep Deformation - T o Figure 38. Compression Yield Strength of 2024-T86 Alloy at Exposure Temperature after Prior Creep for 10, 50, or 100 Hours at 3500, 400', or 500'F

20 - ~. —\&O 4 = 00 o 4i o A Exposure Temperature, 10 _ E, 10 _ 0-350~F O A 400~F.~ ^ 0 O 500~F ^ ~ Room-Temperature Tests Q u 0 10 20 30 40 50 60 70 80 90 100 Exposure time - hours 30 4J M'SoD~~~.-~~~~ ~Exposure and 6s~~~~~~~~~ ~~~Test Temperature _ 20 0 350F ^5f ( — ----- 400'F 8 F -- -g 500~F W 10 Elevated-Temperature Tests 0I I....-..1 0 10 20 30 40 50 60 70 80 90 100 Exposure'Time - hours Figure 39. - Effect of Unstressed Exposure on Tension Impact Strength of 2024-T86 Alloy. WADC TR 57-150 102

LOT OST-LZ II OCIGVi ~/ Tension Impact Strength - t. Ilb. Tension Impact Strength -ft. b, Tension Impact Strength - ft. lb.'. - o i~ o ^.- M Mo o o o o o C \C.. 0 o o 0 O o 00 cC 0 C, 3 0 Il ~'(D O S. " P-? /D L nc * I I 0^ 3~3'. o, N' OO.:.T ma S t l CD 0 CP.. 0 ~~~~ 0 In~~~~~~~~~~~~~~~10 VI a 1 Tension Impact Strength - ft. lb. Tension Impact Strength - ft. lb. VI C) to 00 a 0/ N 0 0*=- 0 0 1\ (D r+ oo 00oI <j 0 * ~ ~ ~ ~ ~ a S **

Keller's Etch X100 Kellers Etch X100 As Received (Cold Rolled and Artificially Spec No. 2M-T5 Exposed 100 Aged) hrs at 350~F and 28,000 psi; Total Deformation 0. 52% Keller's Etch X100 Spec. No. 3D-T55 Exposed 100 hrs at 500~F and 14,500 psi; Total Deformation 0. 62% Figure 41. - Representative Photomicrographs of the 2024-T86 Alloy WADC TR 57-150 104

Marble's Reagent X1000 Marble's Reagent X1000 Condition A TH 1050 Condition (see page 4) (Annealed at 1925'F + Air Cool) No. 4 Etch X1000 (TH 1050) Spec. No. 1U-T4 Tested 555 hrs at 800F and 90, 000 psi Figure 42. - Representative Photomicrographs of the 17-7PH Alloy WADC TR 57-150 105

10 HOURS PRIOR CREEP EXPOSURE 100 HOURS PRIOR CREEP EXPOSURE 4 80 80 0f o Initial 0 o - ~ --- --- -- - ________^ ^ Initial 00 0 70 r 70 U,1 S 35.0 0ps o p,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~s c-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~c 60 Ro Zero Stress S Room Temperature Strength I Stress 60 Room Temperature Strensth | 0,^~ ~ ~ ~~~~~~ 10, OOO psi -- 27,500 Psi Cs 480 0 s4) A l.O ps |j * ^ 50 - \ 7 n r s 4015000, 0 pi Zero Stress 4000 q40,000 P*l 7,000 psi 1 50 HS 40,000 i\i^ 17.000pi 5 P5 I x^ 5,000 psi P, 30,000 p~i-~~ \ 7,30spsi |E. | ^E 30.000 pri-c^ V7. 500 psi o ~ ~~~~~~~~~I IH4 0 (S 0 I I 10,000 psi I a'. 20.000 psi 0 I 00011si 2 OOOpsi 4 40- ________ _ __ 0 100 200 300 400 500 0 100 200oo 300 400 500 Exposure Temperature Exposure Temperate 0 *Expos ure Temperature 60 60:J ~~~~~~~20, 000 psi (7s~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4 30,000 psi 15,000 psi I 50 a'^^ K 5*0^^ Elvated Tem5eratur 35,000 psi 50 Elevated Tem erature 20,000 psi Str Strength _______ —--- ^ 1~~~~~~~~ \ \\enR~ ~ 27,500 Dsi k~~~~~~~~~~~~~~~ 14 I \,' 0 40 I 1 1 0- \\ Zero Stress 40 cd~' I \ \ \ Zero Stress 40~~~~~~~~~~~~~~~ I ~l\ 0,000 psi I I o I | 30 48, OOO psi-iJ 1 15,OOOpsi 30 40, 000 psi-P \ 50 psi 40, 000psi —-= | \ 17,000 psi 30,000 psi 7,500psi 30, 000 ps14,00 5" 1 I \ 12,500 psi 20, 000 psi i 1 S p 20 20 0s1\'~~~~~~.4-^ _____ I _ i^'^~opi 0-__________________.1'000 0 100Q 200 300 400 500 0 100 200 300 400 500 Exposure Temperature and Test Temperature - FExposure Temperature and Test Temperature - F Figure 43. - Effect of Exposure Temperature and Stress on Subsequent Room-Temperature and ElevatedTemperature Tensile Strengths of 2024-T86 Aluminum Alloy Subjected to 10 or 100 Hours of Prior Creep Exposure.