WADC TECHNICAL REPORT 59-454 EFFECT OF PRIOR CREEP ON THE MECHANICAL PROPERTIES OF A HIGH-STRENGTH HEAT-TREATABLE TITANIUM ALLOY, Ti-16V-2. 5A1 Jeremy V. Gluck James W. Freeman The University of Michigan Research Institute March 1959 Materials Laboratory Contract No. AF 33(616)-3368 Supplement No. 3(58-1715) Project No. 7360 Wright Air Development Center Air Research and Development Command United States Air Force Wright-Patterson Air Force Base, Ohio

FOREWORD This report was prepared by the University of Michigan Research Institute under USAF Contract No. AF33(616)-3368. This contract was conducted under Project No. 7360, "Materials Analysis and Evaluation Techniques," Task No. 73604, "Fatigue and Creep of Materials. " The work was administered under the direction of the Materials Laboratory, Directorate of Laboratories, Wright Air Development Center, with Lt. W. H. Hill acting as project engineer. The report covers work conducted from July 8, 1958 to March 31, 1959. The research is identified in the records of the University of Michigan Research Institute as Project 2498. WADC TR 59-454

ABSTRACT A study was carried out of the effect of exposure to elevated temperature creep conditions on the short-time mechanical properties of a high-strength, heat-treatable titanium alloy, Ti-16V-2, 5A1. Exposures were conducted for 10 or 100 hours either unstressed or at stresses causing up to 2-percent creep deformation at temperatures between 600~ and 900~F. The specimens were taken parallel to the sheet rolling direction, Following the exposures, short-time tension, compression or tension-impact tests were run at room temperature or the temperature of exposure. Prior creep at 6000F raised the ultimate tensile strength and tensile yield strength considerably and the compressive yield strength and tensile elongation were substantially decreased. Exposure to temperature alone caused increases in strength indicative of an age-strengthening reaction. The changes in mechanical properties are attributed mainly to a combination of stress-accelerated age-strengthening and a Bauschinger effect. A lesser change in properties was noted for creep exposures conducted at 700~F, Peak properties from the age-strengthening reaction were noted in the unstressed exposures conducted at 800~F and overaging with a consequent drop-off in strength was obtained from the 900~F creepexposures. Metallographic evidence tended to confirm the presence of stress-accelerated aging. PUBLICATION REVIEW This report has been reviewed and is approved. FOR THE COMMANDER: W. J. TRAPP Chief, Strength and Dynamics Branch Metals and Ceramics Division Materials Laboratory WADC TR 59-454 iii

TABLE OF CONTENTS Page INTRODUCTION............... EXPERIMENTAL PROGRAM.......... 2 TEST MATERIAL AND SPECIMENS...... 4 TEST EQUIPMENT AND PROCEDURES...... 7 EXPERIMENTAL RESULTS........... 8 BASE PROPERTIES BEFORE CREEP EXPOSURE.. 8 T ension Properties.......... 8 Compression Properties........ 9 Tension-Impact Properties......... 9 Transverse Properties.......... 9 Hardness Properties......... 10 ESTABLISHMENT OF EXPOSURE STRESSES.. 10 TENSION AND COMPRESSION PROPERTIES AFTER EXPOSUR E..... *. 12 Unstressed Exposure......... 12 Room Temperature Tension Tests... 12 Elevated Temperature Tension Tests.. 12 Room Temperature Compression Tests. 13 Elevated Temperature Compression Tests.. 13 Creep Exposure............. 13 Room Temperature Tests........ 13 Creep-Exposure of Transverse Specimens.. 16 Elevated Temperature Tests....... 16 TENSION-IMPACT PROPERTIES AFTER EXPOSURE. 18 Unstressed Exposure........... 18 Room Temperature Tests....... 18 Elevated Temperature....... 18 Creep Exposure............. 19 Room Temperature Tests........ 19 Elevated Temperature Tests....... 19 METALLOGRAPHIC EXAMINATION OF Ti-16V-2.5A1. 20 DISCUSSION.,............... 2 1 CONCLUSIONS.......... 25 REFERENCES.............. 26 WADC TR 59-454 iv

LIST OF TABLES Table Page 1. Tensile Test Data for Ti-16V-2.5A1....... 27 2. Compression Test Data for Ti-16V-2. 5A1.. 28 3. Tension-Impact Data for Ti-16V-2. 5A1....... 29 4. Rupture and Creep Deformation for Ti-16V-2. 5A1 Alloy. 30 5. Effect of Unstressed Exposure on Tensile Properties of Ti-16V-2.5A1...............31 6. Effect of Unstressed Exposure on Compression Properties of Ti-16V-2.5A1.. 32 7. Effect of Prior Creep on Room Temperature Tensile Properties of Ti-16V-2. 5A1.......... 33 8. Effect of Prior Creep on Room Temperature Compression Properties of Ti-16V-2. 5A1....34 9. Effect of Creep Exposure on Mechanical Properties of Transverse Specimens of Ti-16V-2.5A...... 35 10. Effect of Prior Creep on Elevated Temperature Tensile Properties of Ti-16V-2. 5A1........36 11. Effect of Prior Creep on Elevated Temperature Compression Properties of Ti-16V-2.5A1...37 12* Effect of Unstressed Exposure on Tension-Impact Properties of Ti-16V-2.5A1......... 38 13. Effect of Prior Creep on Tension-Impact Properties of Ti-16V-2.5A1............ 39 WADC TR 59-454 v

LIST OF ILLUSTRATIONS Figure Page 1. Sampling Procedure for Ti-16V-2.5A1... 40 2, Details of Test Specimens * *. 41 3. Effect of Test Temperature on Tensile Properties of Ti-16V-2.5A1........ 42 4. Effect of Test Temperature on Compression Yield Strength of Ti-16V-2.5A1......... 43 5. Effect of Test Temperature on Tension-Impact Properties of Ti-16V-2.5A1..... 44 6. Stress Versus Time to Reach Indicated Creep Deformation for Ti-16V-2.5A1 at 600~, 8000 and 9000F........... 45 7. Effect of Deformation in 10 hour to 1030 hour Creep Tests at 600~, 800~, and 900~F on Room Temperature Tensile Properties of Ti-16V-2.5A1. 46 8. Effect of Unstressed Exposure on Room Temperature Tensile Properties of Ti-16V-2.5A1..... 47 9. Effect of 100 Hours Unstressed Exposure on Room Temperature Tension and Compression Strengths of Ti- 16V-2.5A1.......... 48 10. Effect of Unstressed Exposure on Elevated Temperature Tensile Properties of Ti-16V-2.5A1.. 49 11. Effect of Unstressed Exposure on Room Temperature Compression Yield Strength of Ti-16V-2.5A1. 50 12. Effect of Unstressed Exposure on Elevated Temperature Compression Yield Strength of Ti- 16V-2. 5A1....... 51 13. Effect of Prior Creep Exposure at 600~F on Room Temperature Tension and Compression Properties of Ti-16V-2.5A1........ 52 14. Effect of Total Plastic Strain Reached in CreepExposure at 600~F on the Room Temperature Tension and Compression Properties of Ti-16V-2. 5Al.. 53 WADC TR 59-454 vi

LIST OF ILLUSTRATIONS (Continued) Figure Page 15. Effect of Prior Creep Exposure at 700~F on Room Temperature Tension and Compression Properties of Ti-16V-2.5A1........*. 54 16. Effect of Prior Creep Exposure at 800~F on Room Temperature Tension Properties of Ti-16V-2.5A1. * 55 17. Effect of Prior Creep Exposure at 900~F on Room Temperature Tension and Compression Properties of Ti-16V-2.5A1............ 56 18. Effect of 100-Hour Exposure at 600~ to 900~F Either Unstressed or to 1%o Creep on Room Temperature Tension and Compression Properties of Ti-16V-2.5A1.............. 57 19. Effect of 10-hr Creep Exposure at 600~F on Room Temperature Tension and Compression Properties of TRANSVERSE SPECIMENS of Ti-16V-2.5A1.. 58 20. Effect of Prior Creep Exposure at 600~F on Tension and Compression Properties of Ti-16V-2. 5A1 at 600~F................ 59 21, Effect of Prior Creep Exposure at 800~F on Tension and Compression Properties of Ti-16V-2. 5A1 at 8000~F................ 60 22. Effect of Prior Creep Exposure at 900~F on Tension and Compression Properties of Ti-16V-2.5A1 at 900F................ 61 23. Effect of Unstressed Exposure on Room Temperature Tension-Impact Properties of Ti-16V-2,.5A1.... 62 24. Effect of Unstressed Exposure on Elevated Temperature Tension-Impact Properties of Ti-16V2.5A1............. 63 25. Effect of Prior Creep Exposure on Room Temperature Tension-Impact Properties of Ti-16V-2. 5A1... 64 26. Effect of Prior Creep Exposure at 600~ or 900~F on Elevated Temperature Tension-Impact Properties of Ti - 16V-2Z. 5A1 65 WADC TR 59-454 vii

LIST OF ILLUSTRATIONS (Concluded) Figure Page 27. Electron Micrographs of Ti-16V-2.5A1 Alloy *.. 66 28. Electron Micrographs of Ti-16V-2.5A1 Alloy.. 66 29. Electron Micrographs of Ti-16V-2.5A1 Alloy.. 66 30. Electron Micrographs of Ti-16V-2.5A1 Alloy... 66 31, Electron Micrographs of Ti-16V-2.5A1 Alloy.. 66 32. Electron Micrographs of Ti-16V-2.5A1 Alloy. 66 33. Electron Micrographs of Ti-16V-2.5A1 Alloy., 67 34. Electron Micrographs of Ti-16V-2.5A1 Alloy., 67 35. Electron Micrographs of Ti-16V-2. 5A1 Alloy.. 67 36. Electron Micrographs of Ti-16V-2. 5A1 Alloy.. 67 37. Electron Micrographs of Ti-16V-2. 5A1 Alloy.. 67 38. Electron Micrographs of Ti-16V-2, 5A1 Alloy.. 67 WADC TR 59-454 viii

INTRODUCTION An investigation was conducted to study the effects of prior creep-exposure at elevated temperature on the short-time mechanical properties of a high strength, heat-treatable titanium sheet alloy, Ti-16V-2. 5A1. This material is one of a series of aircraft structural metals investigated under a program sponsored at the University of Michigan by the Materials Laboratory, Wright Air Development Center, U. S. Air Force, under Contract No. AF33(616)3368 and its accompanying Supplemental Agreements. Other materials studied in this investigation have included 2024-T86 aluminum alloy (Ref. 1), C1IOM titanium alloy (Refs. 2 and 3), and 17-7PH stainless steel in the TH 1050 condition (Ref. 4) and the RH 950 condition (Ref. 5). The Ti-16V-2. 5A1 alloy which contains 16-percent vanadium and 2.5-percent aluminum was developed by the Mallory-Sharon Metals Corporation and produced under the auspices of the Department of Defense Titanium Sheet Rolling Program as one of a group of "second generation" titanium alloys suitable for production in sheet form. The inclusion of this alloy in the present investigation made possible the comparison of two titanium alloys of widely differing composition inasmuch as C 10M was a binary alloy containing 8-percent manganese. The purpose of these studies of structural metals is to provide the necessary background information to aid in the formulation of principles for the prediction of creep damage to short-time mechanical properties. The need for stable short-time properties has become important as flight vehicle design and performance requirements have progressed to the point where creep conditions are attained during a portion of the normal operating cycle. It is not only important that creep strength be sufficient to withstand these conditions but the subsequent short-time properties must also not be adversely affected. The short-time properties are of primary concern in connection with such events as high-intensity stresses of brief duration or the thermal stresses encountered in either heating or cooling. "Manuscript released by authors June 19, 1959 for publication as a WADC Technical Report. " WADC TR 59-454 1

EXPERIMENTAL PROGRAM The creep-exposures of the Ti-16V-2.5A1 alloy were conducted principally at 600~, 800~, and 900~F with some additional studies conducted on specimens crept at 700~F. Specimens were exposed for 10, 50 or 100 hours without stress or for 10 or 100 hours at stresses selected to produce nominal creep deformations of 0.2, 0.5, 1.0, and 2.0 percent in the desired time period. Creep deformation is defined as all deformation occuring between the completion of loading and the end of the test period. The creep deformation therefore does not include either the elastic or plastic deformation, if any, of loading. The creep stresses used were those which had been determined by a series of preliminary tests to give, on the average, the desired amount of creep. Since the time, temperature, and stress of testing were fixed, the inherent scatter of creep properties produced actual deformations that were sometimes greater or less than the desired value. Time-elongation data were taken for all tests and all correlations were based on the actual amounts of deformation obtained. The deformation data were tabulated as follows: Total loading deformation, plastic loading deformation (if any), creep deformation, total plastic deformation (both loading and creep), and total deformation (all deformation elastic and plastic occuring during the application of the load and during the creep period). After the exposures, the following mechanical property tests were carried out: 1. Tension tests at room temperature and the exposure temperature. The data reported are the ultimate tensile strength, 0.2-percent offset yield strength, elongation, reduction of area, and the elastic modulus. While the reduction of area data are reported, the accuracy of such measurements on thin sheets is questionable. The modulus values were computed from the slopes of the stress-strain curves and should not be regarded as precise determinations. 2. Compression tests at room temperature and the exposure temperature. The data reported are the 0.2 percent offset yield strength and the elastic modulus. WADC TR 59-454 2

3. Tension-impact tests at room temperature for specimens exposed 10 hours at each temperature and at the exposure temperature for specimens exposed for 10 hours at 600 or 900~F, The data reported are the tension-impact strength, elongation, and reduction of area. 4. Hardness determinations on representative tensile specimens. Metallographic examination was also carried out on selected test specimens. Most of the test specimens were taken from the sheets in the direction parallel to rolling. This was believed to be weaker than the transverse direction of the material. A few additional tests were conducted on specimens taken transverse to the rolling direction. The properties of specimens subjected to creep-exposure were compared to the average properties of the as-treated material as established by a series of tests performed to define the normal scatter of each property. In most cases only single specimens were tested for each exposure condition. Significant effects were defined as those which resulted in short-time properties outside the scatter band for the original material. The conditions used to fix the base properties were inadequate to fix realistic confidence limits by statistical methods. Under these conditions the information gained from the study of simple trends is probably as effective as that which would have been gained using the statistical approximations necessary with the small sample sizes. Duplicate exposure tests were, however, run in several instances in order to give more confidence in the results. WADC TR 59-454

TEST MATERIAL AND SPECIMENS The Ti-16V-2.5A1 alloy used in the present investigation was allocated from the Department of Defense Titanium Sheet Rolling Program. Three sheets, identified as Sheets No. 0084-1, 0084-2, and 0084-7 from Heat No. M-22154, were received from the MallorySharon Metals Corporation during July of 1958. The material was of nominal 0.063-inch thickness by 36 inches wide by 92 to 105inches long. The material had been solution heat treated and aged by the producer according to the following schedule: solution treated 1/2-hour at 1380~F; water quenched; aged 4 hours at 990~F; air cooled. The following chemical analysis was reported: Element Percent (wt. ) C 0.02 N2 0.014 H2 0.0076 Fe 0.27 Al 2.56 V 15.79 In addition, the producer furnished mechanical property data for the three sheets: Room Temperature Properties Ult. Tensile Yield Strength Elongation H2 Sheet No. Direction (psi) (psi) (%) ppm 0084-1 L 167,000 153,800 7.3 76 L 167, 100 155,700 6.8 T 1._67,800 1.mm mmm_56,300 6m_.0 _ T 167,500 156,700 6.0 ~TWADC TR 59-454156 6. WADC TR 5_ 45 4

Room Temperature Properties Ult, Tensile Yield Strength Elongation H2 Sheet No. Direction (psi) (psi) (%) ppm 0084-2 L 178,000 164,600 6.5 76 L 178,900 165,000 6.5 T 184, 100 164,600 4.5 T 184,500 165,000 5.0 0084-7 L 169,700 153,200 7.0 78 L 169,400 155,800 6.5 T 175,300 160,900 5.0 T 175,900 161,000 5.0 Examination of these data revealed good agreement in properties between Sheets 0084-1 and 0084-7, while Sheet 0084-2 was slightly stronger and less ductile. While the deviation was not considered excessive, it was decided to set aside Sheet 0084-2 for the time being and conduct the creep-exposure studies on the two sheets showing closer correspondence in properties. The plan used for sampling specimen blanks is illustrated in Figure 1. With few exceptions the specimens were taken in the direction of rolling. Each sheet was divided into one-inch wide strips running the length of the sheet. The strips were numbered consecutively from 1 to 36 from one edge of the sheet to the other. The length of the sheet was divided into four sections (A, B, C, and D) approximately 26-inches long in the case of Sheet 0084-1 which was 105-inches in length and 23-inches long in the case of Sheet 0084-7 which was only 92-inches in length. As the individual specimens were sheared from each blank they were stamped with a code number identifying their source: thus a specimen labeled 1CL17T is a tensile specimen taken in the longitudinal direction on strip 17, section C, of Sheet Number 0084-1. Compression specimens were coded "C" and tension-impact specimens were coded "M". The transverse samples were coded with a "T" instead of an "L" following the sheet number and section letter, while the transverse strips were identified as 1, 2, 23, 25 or 26, depending on the side of the section from which they were taken. Tension-impact and compression specimen blanks were cut from tensile blanks. In some cases tensile specimens of less than the normal 22-inch length were WADC TR 59-454 5

prepared from the material remaining after sampling the compression blanks. These specimens were used only for tests of base properties or unstressed exposure where furnace clearance was not critical. In all respects except overall length the short specimens were identical to the standard specimens. The configurations and dimensions of the test specimens are illustrated in Figure 2. All specimens were designed so that they could be machined from the creep specimens following the desired exposure. For exposure to creep, the width of the gage section was machined 0.030-inch over the 0.5-inch nominal width. The excess was machined off after exposure and thus permitted the measurement of the properties of the material to be made without interference from the particular edge effects, if any, associated with the exposure of the specimen. For convenience and uniformity in machining, jigs were constructed so that five or six specimens could be made concurrently. The blanks were milled to rough dimensions and then the shoulder radii and gage sections were ground to the finished dimensions. WADC TR 59-454 6

TEST EQUIPMENT AND PROCEDURES Detailed discussion of the development of the test equipment and procedures has been previously given (Refs. 1 and 4) and will not be repeated in the present report. Wherever applicable, ASTM Recommended Practices were adhered to in test procedures. The creep-exposure tests were carried out in individual creeptesting machines with heating provided by a wire wound resistance furnace fitting over the specimen assembly. Strain measurements were accomplished using a modified Martens optical extensometer system. Tensile and compression tests were conducted in a BaldwinSouthwark hydraulic tensile machine equipped with a strain pacer to give a strain rate of 0.005-inches per inch per minute. A recording extensometer system employing a micro-former strain gage was employed to give a continuous plot of the test results. A special compression testing fixture which included a loading ram and a pair of guide blocks to restrain lateral buckling of the specimen was constructed for use in this investigation. Specimens prepared for electron microscope examination were mounted in bakelite and wet ground on rotating laps using a series of silicon carbide papers through 600 mesh. Final polishing was carried out first with fine diamond compound and then on a Syntron vibratory polisher in an acqueous media of Linde "B" polishing compound. The polished samples were etched with "R" etch —composed of 13.5 gm Benzalkonium Chloride, 35 ml Ethanol, 40 ml Glycerine, and 2r n! Hydrofluoric acid (20%) —by swabbing for 3-4 seconds. For electron microscope examination, collodion replicas were made from the surface of the etched specimens. The replicas were shadowed with palladium to increase contrast and reveal surface contours. Polystyrene latex spheres of approximately 3400 A diameter were placed on the replicas prior to shadowing to indicate the angle and direction of shadowing and provide an internal standard for the measurement of magnification. The micrographs reproduced in this report are direct prints from the original negatives; consequently the polystyrene spheres appear black and the shadows appear white. Since the latex spheres are raised in the replica, a phase casting a shadow opposite to that cast by the latex spheres is in relief on the metal specimen; conversely, areas casting shadows in the same direction as cast by the latex spheres are depressions in the surface of the metal specimen and represent a phase that was attacked by the etchant. WADC TR 59-454 7

EXPERIMENTAL RESULTS The experimental results are presented in the form of tabulations of the test data and such graphical representations as are needed to clearly delineate the effects observed. The data are organized both by type of short-time test conducted and the prior exposure condition. Following the discussion of the base properties, the effects of unstressed exposures and creep exposures are considered for each mechanical property. The metallographic studies are presented after the mechanical property data. BASE PROPERTIES BEFORE CREEP EXPOSURE Tension, compression, and tension-impact tests were conducted in order to establish the average strength of the as-treated material at both room temperature and at the temperatures of creep-exposure. Two specimens each were taken at andom from the two sheets studied and the results were averaged to provide the basis for comparison with the properties following the creep-exposures. Tension Properties The results of tension tests at room temperature, 600~, 800~, and 900~F are summarized in Table 1. A plot of the effect of test temperature on the ultimate tensile and yield strengths and elongation is presented in Figure 3. Fairly good agreement in the tensile and yield strengths was obtained both within sheets and between sheets. Most of the values fell within 5-percent of the average value while in only two cases was the deviation as much as 8 percent. Both the tensile and yield strengths decreased to the same extent as the temperature increased. The elongation underwent little change between room temperature and 600~F, remaining at about 8-percent. At 800~ and 900~F it increased, reaching a value of about 25 percent at 900~F. The average room temperature ultimate tensile and tensile yield strengths determined at the University were within 2.5-percent of the values reported by the producer. A slightly higher value of elongation was obtained at the University. WADC TR 59-454 8

Compression Properties The compression test data for the room temperature and elevated temperature tests are presented in Table 2 and plotted as a function of temperature in Figure 4. The yield strength in compression decreased with test temperature. The fall-off in strength was more rapid than was noted for the tensile properties. The compressive yield strength at room temperature was approximately equal to the ultimate tensile strength while at 900~F it had fallen below the level of the tensile yield strength. At room temperature the compressive yield strength was 112-percent of the tensile yield strength while at 900~F it was 93-percent of the tensile yield strength. At all the test temperatures except 800~F, the variation between tests and between sheets was slight and was not over 2 to 3-percent from the average value. Two tests at 800~F, one from each sheet, deviated from 7 to 8-percent from the average at 800~F. The modulus values observed in compression averaged slightly higher than the corresponding values observed in tension. Tension-Impact Properties The results of the room temperature and elevated temperature tension-impact tests are summarized in Table 3 and plotted in Figure 5. The tension-impact strength decreased somewhat with increasing test temperature while the reduction of area was slightly increased, The elongation, on the other hand, did not change significantly with the test temperature. Fairly good agreement was obtained both between sheets and within sheets. Transverse Properties In addition to the complete tests of longitudinal specimens a few check tests were made on transverse specimens of Ti-16V-2.5A1, A comparison of the as-treated short-time properties of the two directions follows: WADC TR 59-454 9

Test Ult. Tensile Yield Strength Elong. R.A. Modulus Direction Type of Test (psi) (psi) (To) (%) (x 106psi) Trans. Tensile 165,200 152,000 6.5 18.6 14.2 Long. Tensile(Sht. 1) 167,600 152,650 8. 8 20.5 14. 6 Trans. Comp. --- 175,000 - -- 18.6 Long. Comp. (Sht. 1) --- 169,000 - -- 15.3 Note: Transverse tests were run on specimens from Sheet 1. Comparative longitudinal data is the average for Sheet 1. The tensile strengths in the transverse direction showed good agreement with those for the longitudinal direction, while the elongation was slightly less. This observation agrees with the data furnished by the producer (p. 4). The apparently increased compression yield strength in the transverse direction may not be real inasmuch as the deviation was only slightly more than the experimental variation noted in duplicate tests of longitudinal samples. An effect of test direction on compression modulus was noted for previous tests of the C1lOM titanium alloy (Ref. 3). This may also have been the case in the present alloy. Hardness Properties The hardness of solution treated and aged Ti-16V-2.5A1 was determined to be Rockwell "C" 36.8. This value is the average of five determinations each on four room temperature tensile specimens. ESTABLISHMENT OF EXPOSURE STRESSES The stresses for the creep-exposure tests were determined from curves of creep deformation established at 600", 800~, and 900~F. It was the aim of these tests to establish the curves for 0.2, 0. 5, 1. 0 and 2 0 percent creep deformation in periods up to 100 hours. The nominal stresses for the creep exposures were then taken as the intersection of these curves with the ordinates at 10 or 100 hours. In some cases, further experience with the creep exposure tests necessitated readjustment of the stresses. This additional information was also used to revise the creep deformation relationships. The data for these tests are summarized in Table 4 and plotted in Figure 6. The tests were usually discontinued once the limit of useful information had been reached although one specimen each was WADC TR 59-454 10

allowed to run until fracture at 800~ and 900~F. The unfractured creep specimens were tensile tested at room temperature in order to gain some indication of the effect of creep-exposure. In the 6000F creep tests considerable difficulty was encountered in fixing the curves for 1.0 and 2.0 percent creep deformation. The stresses required to reach this deformation in a short time were quite close to the ultimate strength and two tests were even run successfully at 140,000 psi, a stress above the 139,250 psi determined by shorttime testing to be the average strength at this temperature. A large amount of short-time plastic deformation occurred during loading of a number of the 600~F creep specimens. This was a consequence of using test stresses above the proportional limit in order to reach the desired amount of creep deformation. In the tests conducted at 800~ and 900~F the required amounts of creep deformation were generally obtained without the necessity of using stresses above the yield strength. The creep deformation relationships at these temperatures were establish with little difficulty. Tension tests at room temperature of the discontinued creep specimens revealed changes in the strength and ductility from the as-treated condition. In Figure 7 the ultimate tensile strength, tensile yield strength, and elongation are plotted as a function of the total plastic strain in the creep test. The creep time is indicated for each point. Since these data represent a wide range of creep time as well as deformations no attempt was made to draw correlation curves. The specimens crept at 6000F for periods between 10 and 1030 hours all had increased tensile strength and yield strength and decreased ductility from the as-treated condition. The increase in tensile strength ranged from 6-percent to 35-percent over the base value; the increase in yield strength ranged from 18 to 35-percent over the base value; while the absolute value of the elongation dropped from nearly 9-percent down to only one percent. It appeared that the change in properties from 6000F creep was more a function of the amount of prior creep than of the time of exposure. The specimens crept at 800~F had increased ultimate tensile strength and tensile yield strength and slightly decreased ductility. The increase in tensile strength was moderate and reached only 9 percent over the base value while the yield strength increased as much as 20 percent. The lowest elongation observed was 4.3-percent. Again there was an indication that the properties after exposure were affected by the amount of prior creep. WADC TR 59-454 11

The specimens crept at 900~F all had a decreased ultimate tensile strength and exhibited little or no change in the tensile yield strength with increased creep. The decrease in ultimate strength ranged from 6 to 12 percent of the base value while the variation in the tensile yield strength was only 5 percent of the base value. This is within the variability of the base condition. In two of the four specimens crept at 9000F the elongation was slightly higher than the base condition; in the other two it was reduced. The specimens crept at 600 or 8000F had an increased hardness of up to 3 points Rockwell "C" while the specimens crept at 900~F had either an unchanged or slightly decreased hardness. TENSION AND COMPRESSION PROPERTIES AFTER EXPOSURE Unstressed Exposure Room Temperature Tension Tests. Tension tests were conducted at room temperature on specimens exposed without stress for 10, 50 or 100 hours at 6000, 800~, and 900~F. Additional tests were later conducted on specimens exposed at 700~F for 10 or 100 hours. The test data are tabulated in Table 5 and plotted as a function of exposure time and temperature in Figure 8. The effect of the unstressed exposures on the room temperature properties was small but showed some consistency. The ultimate strength curves fell within a range of + 5 percent of the base condition while the yield strengths were either unaffected or increased up to 15 percent above the base value depending on the exposure temperature and time. Little or no change was observed in the elongations of these specimens. Exposure at 6000F had little effect on the ultimate tensile or tensile yield strengths, while the 700~ and 800~F exposures produced increased strengths. The exposure at 900~F caused the strengths to drop back close to the original values. A cross plot of these data at an exposure time of 100 hours slows the effect more clearly (Figure 9) and indicates that the material increased in strength as a result of further aging up to 800~F and was probably overaged at 900~F. The hardness data in Table 5 tend to confirm this. Elevated Temperature Tension Tests. The results of tension tests conducted at the exposure temperature following unstressed exposure are summarized in Table 5 and plotted in Figure 10. WADC TR 59-454 12

The effects of the unstressed exposure on the elevated temperature properties were generally small. The ultimate strength at 6000F after 100 hours exposure and the ultimate strengths after all the exposures at 800~ or 900~F were increased about 6-8 percent. The increases in the yield strength were slightly greater and reached 10 to 15 percent for the 50 hour exposures at 800~ or 900~F, The ductilities, however, were apparently unaffected. Only the specimens tested at 800~F showed any increase in hardness. Room Temperature Compression Tests, The results of room temperature compression tests on specimens subjected to unstressed exposure are summarized in Table 6 and plotted in Figure 11. All of the unstressed exposures caused some increase in the compressive yield strength. The increase in strength ranged from 4 percent above the base value for 10 hours exposure at 600~F to 14 percent for 100 hours exposure at 800~F. The increased strength appeared to be principally dependent on temperature with the time of exposure a minor factor, A cross plot of the data for 100 hours exposure is included in Figure 9 and shows that the compressive yield strength behaved in a manner similar to the ultimate tensile and tensile yield strengths as a function of the exposure temperature. The strength was increased with temperature and reached a peak for the exposure at 800~F, It then dropped off somewhat at 900~F. This behavior is again indicative of an aging reaction. Elevated Temperature Compression Tests. The data for the elevated temperature compression tests following unstressed exposure are summarized in Table 6 and plotted in Figure 12. Unlike the elevated temperature tensile properties, the compressive strength was significantly affected by the unstressed exposure. Although the 6000F strength was increased only 8 percent above the base value at 600~F, the 800~F strengths were increased up to 30 percent and the 900~F strengths were increased up to 44 percent. The greatest part of the increased strength at 800~ and 900~F occurred in the first 10 to 20 hours of the exposure period. The slight increase in strength occurring at 6000F took place over the entire test period. Creep Exposure Room Temperature Tests, Creep-exposure tests were run for 10 or 100 hours at 600~, 800~, and 900~F. Some additional tests were then run at 700~F in order to clarify the initial results. The room temperature tension test data from these exposures are summarized in Table 7 and the room temperature compression test data are summarized in Table 8. Plots of the effect of prior creep WADC TR 59-454 13

on the short-time properties are presented in Figures 13 to 17 for each exposure time and temperature. Creep-exposure at 600~F had quite a substantial effect on the strength and ductility of the Ti-16V-2. 5A1 sheet (Figure 13). The ultimate strength and the tensile yield strength were increased and the compression yield strength and elongation were decreased as the amount of creep was increased. Similar effects were noted in both the 10 and 100 hour exposures. Reference to Table 7 shows that short-time plastic deformation was obtained during loading of most of the specimens exposed at 6000F. This came about since most of the loads required to reach the desired amounts of creep were above the proportional limit. In the 10 hour tests, the short-time loading strain ranged from 30 to 50percent of the total plastic strain, while in the 100 hour tests, the short-time strain ranged from zero to 30 pe~rcent of the total strain. Some trouble with inconsistent premature failure was encountered with several specimens loaded to high stresses at 6000F. For this reason the data only cover creep deformation of up to one percent in 100 hours. Research carried out in another phase of this investigation (Ref. 3) indicated that there was no apparent difference in the relative influence of short-time strain and creep strain in cases where the short-time strain ranged up to 30 percent of the total plastic strain and where there was no opportunity for a no-load recovery period during the test. These conditions were substantially fulfilled during the present exposures to 6000F. Figure 14 presents a correlation of the 6000F creep-exposure data in terms of total plastic strain. These curves had the same shapes as the curves in Figure 13 which were based on creep deformation. There was no apparent difference in the time dependency revealed by either method of correlation. The increase in the ultimate strength after 6000F creep-exposure ranged up to 20 percent above the base value, while the tension yield strength was increased as much as 35 percent. The compression yield strength was reduced to as much as 20 percent. One percent total strain caused the absolute value of the elongation to drop from 8.8 percent down to about one to two percent. The hardness of these specimens was increased only 2-3 points Rockwell "C". Creep-exposures conducted at 700~F had a similar but less severe WADC TR 59-454 14

effect on the tension and compression strength than did the 6000F exposures while the ductility was not particularly decreased. (Figure 15). In these tests virtually all the plastic deformation was obtained during creep and there was no need to consider separately the effect of total plastic strain. The increase in the ultimate strength was barely outside the limit of variability established by the base property tests. The yield strengths, however, were affected to a greater degree. The tension yield strength was increased by a creep deformation of one percent approximately 10 to 12 percent above the value established by exposure to temperature alone, while the compression yield strength was decreased about 22 percent in the 10 hour exposure and only 7 percent in the 100 hour exposure to one percent creep. It will be recalled that both the tension and compression yield strengths were increased about 11 percent over the base value by the exposure at 700~F without stress. For none of the 700~F creep exposures was the elongation reduced below 6.5 percent. The creep-exposures at 8000F had very little effect of significance on the ultimate strength and the elongation and only slight effects on the tension and compression yield strength (Figure 16). The tension yield strength was increased up to about 5 percent by creep in the 10 hour tests while the compression yield strength was reduced up to 8 to 15 percent with increased creep. As was the case in the 700~F exposures, 10 hours creep caused a greater decrease in the compression yield strength than did 100 hours creep. The changes in elongation following 800~F creep-exposure were small and may have been due to experimental variability. Hardness was increased up to 4 points Rockwell "C". Figure 17 shows the effects of creep-exposure at 9000F on the room temperature tension and compression properties of Ti-16V-2.5A1l Again there was very little change in either the ultimate tensile strength or the ductility while the tension and compression yield strengths were affected slightly. The tension yield strength was increased about 9 percent by one percent creep in 10 hours, but less than 4 percent by the same amount of creep in 100 hours. Conversely, the compression yield strength was decreased only 3-4 percent by one to two percent of creep in 10 hours, while the decline in the 100 hour test results was as much as 10 percent. However, most of this decrease was indicated by one test point and the possibility of experimental variability should not be ruled out. Thus the indicated decline may be spurious. The hardness of these samples was increased from one to three points Rockwell "C" above that of the as-treated condition. WADC TR 59-454 15

A clearer understanding of the effects of creep-exposure on the room temperature tension and compression properties of Ti-16V-2.5A1 can be gained from Figure 18. In this figure the mechanical properties are plotted as a function of the exposure temperature for both 100 hours unstressed exposure and for exposure to one percent creep (total plastic strain in the case of the 600~F data) in 100 hours. This figure shows that at 600~F the creep caused a large change in the ultimate tensile and yield strength over that caused by the exposure to temperature alone. The effects of creep on the tensile strength were maintained to a limited extent at 700~F, however, the ductility was not particularly affected. There was a significant difference in compression yield strengths up to 800~F. The increase in tension yield strength and decrease in the compression yield strength with increased creep in the 600~F and 700 F exposures is a manifestation of a Bauschinger effect, while the behavior of the ultimate strength and ductility is due principally to the effect of stress-accelerated age-strengthening. These concepts will be discussed in greater detail in a later section of the report. (pp. 21-24) Creep-Exposure of Transverse Specimens. Creep-exposure tests at 6000F were carried out on two specimens of Ti-16V-2.5A1 taken in the transverse direction to rolling in order to check the previous results on the longitudinal specimens (Table 7). The data from the transverse tests is summarized in Table 9 and plotted as a function of creep deformation or total plastic strain in Figure 19. The results of these tests were similar to the corresponding tests of longitudinal specimens. The ultimate tension strength and tension yield strength were increased with creep and the compression yield strength and the elongation were decreased. The relative extent of the changes was about the same for either test direction. Elevated Temperature Tests. The results of the short-time tests run at the temperature of creep exposure following exposures for 10 or 100 hours at 600~, 800~, or 900~F are summarized in Tables 10 and 11 and plotted in Figures 20-22, In general, the effects noted in the elevated temperature tests were similar to those found in the corresponding tests at room temperature. Creep-exposure at 600~F caused an increase in the ultimate tensile strength and the tensile yield strength, a large decrease in the compressive yield strength, and a moderate decrease in the ductility. WADC TR 59-454 16

(Figure 20). The necessity of using loads low enough to avoid premature fracture at 600~F limited the amount of creep deformation obtained. The maximum increase in the ultimate strength was only about 5 percent in contrast to the 20 percent found in the room temperature tests. The tension yield strength was increased from 16 to 25 percent depending on the exposure time and the compression yield strength was decreased from 20 to 25 percent. These changes were slightly less than the corresponding effects in the room temperature tests. On the other hand, the elongation in the 6000F tests was not reduced as severely as in the room temperature tests. Most of the elongations of these specimens remained above 5 percent. The only exception was a specimen whose reduction of area, however, was not affected. Thus, the low elongation indicated for this specimen may have been due to experimental variability. The hardnesses of the 600~F specimens were very slightly increased above the as-treated hardness. Creep-exposures at 800~F produced little or no change in the 800~F tensile properties but did cause some decrease in the compression yield strength. (Figure 21). The slight changes in the ultimate tensile strength, the tensile yield strength and the elongation were generally within the limits established by the base property tests. There was a slight indication of increased tensile yield strength for one of the specimens exposed to creep for 100 hours. This increase was about 12 percent over the value for the exposure to temperature alone. The compressive yield strength after 10 or 100 hours creep-exposure to one percent deformation was decreased about 12 percent from the value for unstressed exposure. Hardness increases of one to two points Rockwell "C" were noted in these samples. In contrast to the results of the 800~F tests, the creepexposures at 900~F caused apparently significant changes in the 900 F properties (Figure 22). The ultimate tensile strength and tensile yield strength were increased from 10 to 20 percent above the base condition by the application of one to two percent creep. Accompanying the increases in the tensile strength was a decrease in the ductility from an original value of 25 percent down to about 15 percent. The compressive yield strength remained well above the base value, being decreased in the 100 hours exposure only 8 percent from the increased strength that resulted from unstressed exposure. WADC TR 59-454 17

Scatter in the compression test results for the 10 hours exposure made it difficult to correlate the results. This was the only test condition studied for this alloy in which testing scatter made the results uncertain. Apparently, creep exposure for 10 hours at 900~F either increased the 900~F compression yield strength or did not change it. In any event, the changes in the elevated temperature properties after creep-exposure at 800~ or 9000F were not large. In no case was the strength reduced below the value for the as-treated material and the ductilities all remained high. At 600~F, however, the compression yield strength was decreased below the value for the as-treated material while the tension yield strength was substantially increased., These changes in strength were obtained with only a moderate decrease in ductility. TENSION-IMPACT PROPERTIES AFTER EXPOSURE Unstressed Exposure Room Temperature Tests. Data from the room temperature tension-impact tests following unstressed exposure is summarized in Table 12 and plotted in Figure 23. Most of the test points fall within the range obtained for the base property tests of the as-treated material. The 100 hour exposure at 600 F fell slightly below this range while the 50 and 100 hour exposures at 900~F were slightly above the range. The only additional condition showing a large decrease in ductility was the one specimen exposed for 10 hours at 700~F. This may have been due to experimental variability. It appears generally that the unstressed exposure at 600" to 800~F had little effect on the tension-impact properties while the 900~F exposures may have caused some increase in the tensionimpact strength. Elevated Temperature. The results of the tension-impact tests conducted at the exposure temperature following unstressed exposure are summarized in Table 12 and plotted in Figure 24. The data indicate no apparent change in tension impact strength as the result of exposure. The elongations were also not affected significantly. Although some variations were obtained in the reduction of area data they were not consistent and no significance is attached to the variation. WADC TR 59-454 18

Creep Exposure Room Temperature Tests. The test results for specimens subjected to creep and then tension-impact tested at room temperature are summarized in Table 13 and plotted in Figure 25. Because of the lack of effect found in the unstressed exposure tests, the creep-exposures were confined to 10 hours. Creep-exposure at 600~F reduced both the tension-impact strength and ductility of Ti-16V-2.5A1. Creep of up to one percent caused the tension-impact strength to be reduced by about 50 percent from the base value, while both the elongation and reduction of area were reduced to absolute values of about two percent. Test scatter complicated the interpretation of the data for the 700~F creep-exposures. It is possible that the data for the unstressed exposure at 700~Farein error. The correlation curve for this temperature was drawn on the assumption that the unstressed exposure should have produced little change in properties from the base condition. In any event, the loss in tension-impact strength was less than that obtained at 600~F and the ductility does not appear to have been reduced significantly below that of the base condition. The creep-exposure at 8000F caused some decrease in the tension-impact strength but no significant reduction in the ductility. The maximum decline in the strength was about 30 percent below the base condition. This compares fairly well with the test points for the 700"F exposure. Following creep-exposure at 9000F there was a small increase in the tension-impact strength. It is doubtful that this was a real effect. Neither the elongation nor the reduction of area were affected by the 900~F exposures. It appears, therefore, that creep exposure in the range from 600~ to 8000F caused a reduction in the tension-impact strength of Ti-16V-2.5A1 that was somewhat dependent on the amount of prior creep. The maximum reduction in strength ranged from 30 to 50 percent of the base condition. The ductility of the material was only reduced significantly by the 600~F exposures. Elevated Temperature Tests. Tension-impact properties for specimens tested at the temperature of prior creep are summarized in Table 13 and plotted in Figure 26. These results are limited to creep-exposures conducted at 600~ and 900~F. WADC TR 59-454 19

In the tests at 600"F very little change was found in the tension-impact strength as the result of creep-exposure. The ductilities of the specimens were decreased however as the amount of creep was increased. Following creep-exposure at 900~F the tension-impact strength was increased and the ductility was decreased. This behavior was quite similar to that found in the tensile tests at 900~F following creep at 900~F (Figure 22 ). The extent of the losses in ductility following prior creep was about the same in both the 6000 and 900~F tests. METALLOGRAPHIC EXAMINATION OF TI- 16V-2. 5A1. Metallographic examination of the Ti-16V-2.5A1 alloy was made of a number of specimens after creep-exposure. Optical examination of the material was complicated by its extremely fine structure and susceptibility to staining. For example, Figure 27 illustrates the difficulties encountered in trying to interpret optical micrographs of the solution treated and aged condition. A number of the more common titanium etchants were tried with uniformly poor results in attempts to minimize the staining problem. Little success was also had with a 50%H202, loHF, 2%oHN03 plus water, brightening solution suggested by The Mallory-Sharon Metals Corporation. Quite good results were, however, obtained with the use of the electron microscope to examine replicas of the stained surfaces. The as-treated structure is shown at 3500x magnification in Figure 28 and at 8200x magnification in Figures 29 and 30. Figure 29 shows the longitudinal face of the material (i. e, in the direction of rolling) while Figure 30 shows the transverse section (across the thickness of the sheet). The structure consisted of inter-connected, blocklike primary alpha grains in a beta matrix. A very fine alpha precipitate appears throughout the matrix. Changes in the structure as the result of creep-exposure were apparently confined to possible further precipitation and the growth and coalesence of the alpha phase. This shown by Figures 31 and 32, which are the longitudinal and transverse faces of a specimen crept to 1 percent total plastic strain in 100 hours at 6000F. The room temperature tensile elongation of this sample was only 2 percent in contrast to the 8.2 percent elongation of the as-treated condition. WADC TR 59-454 20

The short-time test results indicated that it was the deformation rather than the exposure time that governed properties after exposure at 600~F. Figures 33 for 10 hours exposure and 34 for 1030 hours exposure show that there was some tendency for a reduction in the amount of the fine precipitate in the matrix as the exposure time was increased and an increase in the amount of the primary alpha in both structures as compared to the as-treated condition. Figures 35 and 36 show respectively the structures of specimens that had good ductility after unstressed exposure for 100 hours at 800F or stressed exposure for 10 hours at this temperature. The ductility of these samples was close to the as-treated value, however, the structures apparently were not markedly different from the samples exhibiting brittle behavior after 6000F exposure. Perhaps the greatest change in appearance from the as-treated condition was noted in a specimen crept to one percent deformation in 428 hours at 900~F. (Figures 37 and 38) The fine precipitate in the matrix in the transverse view (Figure 38) particularly showed a considerable amount of growth and agglomeration in comparison to the as-treated condition. The 5.5 percent elongation of this specimen was somewhat below the 8.2 percent of the as-treated condition, however, it was appreciably higher than the elongation of the specimens crept at 600 F. It appears, therefore, that the age-hardening of this material was not complete in the original heat treatment in 4 hours at 990~F. Further transformation probably occurred under the influence of the creep stress at 6000F or at the higher temperatures. It was not clear from the data whether the reaction was a simple one or included a secondary aging peak. It is probable, however, that the sample crept for 428 hours at 900~F was overaged. DISCUSSION The results of this investigation indicate that creep-exposures particularly at 600~ or 700~F, had a significant effect on the short-time strength and ductility of solution treated and aged Ti-16V-2. 5A1 alloy. The changes found were an increased ultimate tensile strength and tensile yield strength and a decreased compressive yield strength and tensile elongation. The effects appear to be more dependent on the amount of prior creep than on the time of exposure. WADC TR 59-454 21

These property changes were the result of two mechanisms: 1. A structural instability of the material resulting in further age-strengthening during testing. 2. The effect of the super-imposed plastic strain of creep which accelerated the age-strengthening, caused the Bauschinger effect and may have produced a slight amount of strain hardening. A good understanding of these effects can be gained from Figure 18 which shows the effect of testing temperature on the mechanical properties following unstressed exposure for 100 hours or exposure to one percent creep in 100 hours. The unstressed exposure caused an increase in the ultimate strength and the tensile and compressive yield strengths that reached a peak at 800~F. This increase in strength was not especially large —amounting only to about 5 percent for the ultimate strength and about 14 percent for the yield strengths. Furthermore, the increased strength was accompanied by little sacrifice in ductility. The original 8.8 percent elongation was only reduced to about 8 percent by the exposure at 800~F. The exposure at 900~F caused a reduction in strength characteristic of over-aging. The addition of creep strain to the 6000F exposures caused quite a substantial increase in the ultimate tensile strength and tensile yield strength above the level for the unstressed exposure. In addition, the compression yield strength was lowered and the elongation was substantially reduced. This behavior was caused by a combination of the two factors mentioned above. Most of the increase in tensile strength was due to stress-accelerated aging. The changes in the yield strength resulted from Bauschinger effects produced by the plastic strain. While only a few percent of plastic strain are required to produce Bauschinger effects, the amount obtained in this investigation was well below that normally required to cause appreciable strain hardening. The Bauschinger effect is defined as "the phenomenon by which plastic deformation of a metal raises the yield strength in the direction of plastic flow and decreases the yield strength in the opposite direction." (Ref. 6) Another report to be issued under this contract deals with the creep-induced Bauschinger effect. (Ref. 3) Consequently, the discussion of the effect in the present report will be limited. WADC TR 59-454 22

The yield strengths measured in this investigation following creep-exposure at 600F are net strengths. The compressive and tensile yield strengths were both increased by the exposure to temperature while the tensile yield strength was increased and the compressive yield strength was decreased by the Bauschinger effect. The observed tensile yield strength is comprised of a plus component from the Bauschinger effect and a plus component from age-strengthening. The observed compressive yield strength is comprised of a plus component from age-strengthening and a minus component from the Bauschinger effect. Furthermore, the ultimate tensile strength was increased mainly by age-strengthening while the adverse effect on ductility followed from the same cause. Since the ductility was not significantly reduced by the unstressed exposure at 600~F, then stress-accelerated age-strengthening must have played a role in reducing the ductility following the 600F creep exposure. Ordinarily, strain-hardening might be considered to be a minor factor since the existence of a Bauschinger effect implies the presence of residual plastic strain which of course is a requisite of strain hardening. However, appreciable strain hardening requires more than the few percent of plastic deformation obtained in these creep exposures. In the 700~F exposures all these factors were operative, however. The higher temperature resulted in less residual plastic strain and the age-strengthening was the major factor affecting the properties. This was evident from the fact that the net compression yield strength after 700~F exposure was considerably higher than the strength following the 600~F exposure. Following the peak age-strengthening effect at 8000~F the properties became dependent principally on the temperature of exposure. As mentioned previously, the 900~F results indicate that the material was over-aged and the ductility data for the 900~F creep-exposures again suggest that the over-aging was stressaccelerated since the ductility was slightly increased. These observations are in fairly good agreement with both the hardness data and the metallographic studies, however, because of the interaction of the effects, it is impossible to establish just what fraction of the net observed change in strength is due to each factor. The behavior of the Ti-16V-2.5A1 alloy was different in several respects from that previously observed for C10OM titanium (a binary alloy containing 8 percent manganese), (Ref. 2) The first difference was that the ClIOM was tested in the hot-rolled and annealed condition and consequently precipitation-hardening or age-strengthening during WADC TR 59-454 23

testing was not much of a factor. There was, however, some breakdown of the beta phase under the influence of the exposure conditions (Ref. 3) that may have resulted in a minor amount of strengthening. In the C1LOM alloy, the Bauschinger effect was found to be at its maximum for the creep exposures at 700 F, while for the Ti-16V-2.5A1 the effect was most marked after the 600~F exposure. It should be noted, however, that the lowest exposure temperature studied for C11OM was 650~F. It is possible that larger effects might have been observed if creep-exposures had been conducted at 6000F. In most respects, however, it appeared that the stressaccelerated transformation of the Ti-16V-2.5A1 made it susceptible to a greater number of changes in properties than the C 1OM was capable of. Thus, the higher strength of the Ti-16V-2.5A1 alloy was obtained at some sacrifice of stability. It should be remembered, however, that the low ductility conditions of Ti-16V-2.5A1 were obtained after creep that was accompanied by a substantial amount of short-time plastic loading strain. In actual practice it is unlikely that loads would be used that were above the yield strength or proportional limit at 600~ or 700~F. Thus, these changes in properties may be more of academic interest than of practical concern. WADC TR 59-454 24

CONCLUSIONS Exposure of solution treated and aged Ti-16V-2. 5A1 sheet to temperatures between 600~ and 900~F and creep deformations of up to 2 percent in 100 hours resulted in changes in mechanical properties that were due to both the structural instability of the material and to the super-imposed plastic strain of creep. Increased tensile strength and decreased elongation after creep exposure at 600~F was attributed mainly to stress-accelerated age-strengthening. An increased tensile yield strength and decreased compressive yield strength were manifestations of the Bauschinger effect caused by the plastic strain from the creep exposure. Exposure to temperature alone caused changes in properties indicative of agestrengthening. A lesser change in properties was noted for creep exposures conducted at 700~F. Peak properties from the age-strengthening reaction were noted in the unstressed exposures conducted at 800~F and a drop in strength from overaging was observed following the 900~F exposures. The application of stress caused little additional effects in the 800~ and 900"F exposures beyond those noted for the exposure to temperature alone. Metallographic evidence supported the existence of an agestrengthening reaction. WADC TR 59-454 25

REFERENCES 1. Gluck, J. V., Voorhees, H. R., and Freeman, J. W. "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals (2024-T86 Aluminum and 17-7PH Stainless)" WADC Technical Report 57-150, January 1957. 2. Gluck, J. V., Voorhees, H. R., and Freeman, J. W. "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals, Part III. C110M Titanium Alloy" WADC Technical Report 57-150, Part III, January 1958. 3. Gluck, J, V., and Freeman, J. W. "A Study of the Creep-Induced Bauschinger Effect in C1IOM Titanium" WADC Technical Report to be issued in 1959. 4. Gluck, J. V., Voorhees, H. R., and Freeman, J. W. "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals, Part II, 17-7PH (TH 1050 Condition). November 1957. 5. Gluck, J. V., and Freeman, J. W. "Effect of Prior Creep on the Mechanical Properties of 17-7PH Stainless Steel (RH 950 Condition)" WADC Technical Report to be issued in 1959. 6. Lyman, T. (editor) Metals Handbook, p. 2, published by American Society for Metals, Cleveland, Ohio (1948). WADC TR 59-454 26

TABLE I TENSILE TEST DATA FOR TI-16V-2.5AI GtU~~~ ~ Test Ultimate 0. 2% Offset 0) Temp. Tensile Strength Yield Strength Elongation Reduction of Modulus,E Hardness (~F) Specimen No. (psi) (psi) (%) Area (%) x 106(psi) R"C" W! Room IAL17T 162,000 149,000 9.0 24.0 14.1 36 ICL4T 173,200 156,300 8.5 17.0 15.1 37.0 167,600 152,650 8.8 20.5 14.6 36. 5 ^ 7BL35T 175,300 152,500 9.0 14.5 15.5 37 3 Cn 7CL14T 180,000 149, 000 8.5 14. 1 14.0 37.2 177,650 150,750 8.8 14.3 14.8 37.2 Average - 4 tests 172,625 151,700 8.8 17.4 14.7 36.8 600 1AL2OT 134,000 112,000 10.0 28.0 12.8 IDL31T 142,000 120,000 7.0 15.0 12.6 138,000 116,000 8.5 22.5 12.7 7AL2T 137,000 117,000 7.0 37.0 12.2 7BL30T 144,000 122,000 9.0 30.0 12.7 140,500 119,500 8. 0 33.5 12.4.,, Average - 4 tests 139,250 117,750 8.2 28.0 12.6 800 1CL3T 130,000 111,000 9.0 25.0 12.0 1DL32T 124,000 105,000 15.0 29.0 11. 3 127,000 108,000 12.0 27.0 11.6 7AL6T 123,500 108,000 11.0 39.5 11.2 7CL17T 122,000 97,000 20.0 38. 1 1. 1 122,750 102,500 15.5 38.8 11.2 Average - 4 tests 124,875 105,250 13.8 32.9 11.4 900 1AL18T 92,700 79,300 20.0 44.0 11.9 IDL30T 103,000 78, 300 27 0 43,0 11.6 97,850 78,800 23.5 43.5 11.8 7AL7T 93,600 77, 300 30.0 64.8 10.0 7CL24T 97,000 82,000 24.5 60.6 9.9 95,300 79,650 27.2 62.7 10 0 Average - 4 tests 96,575 79,225 25.4 53.1 10.9

TABLE 2 COMPRESSION TEST DATA FOR TI-16V-2. 5A1 Test Temp. 0. 2% Offset Modulus, E (~F) Specimen No. Yield Strength, psi x 106(psi) Room IAL14C 168,000 15.6 ICL3C 172,000 15.2 IDL35C 167, 000 15. 1 169,000 15.3 7AL7C 171,000 15.4 7BL25C 168,000 16. 5 7CL13C 172,000 16. 0 170,300 16.0 Average - 6 tests 169, 700 15. 6 600 IAL13C 126,000 13.2 IDL30C 128,000 13.2 ~27,000 13. 7ALIIC 126,000 14.8 7CL14C 132,000 15.0 129,000 14.9 Average - 4 tests 128,000 14.0 800 IAL18C 109,000 12.2 LDL26C 100, 000 12.7 104,500 12.4 7AL2C 108,000 12.2 7CL18C 115,000 12.0 111,500 12. 1 Average - 4 tests 108,000 12 3 900 IAL22C 73,000 11.5 IDL32C 72,700 12.4 72,850 12.0 7BL31C 72,000 11.1 7CL23C 72,700 12.5 72,350 11.8 Average - 4 tests 72,600 11, 9 WADC TR 59-454 28

TABLE 3 TENSION-IMPACT TEST DATA FOR TI-16V-2.5AI Test Temp. Tension-Impact Elongation R.A. (~F) Specimen No. Strength, ft-lb. (%) (%) Room ICL15-3 55 6.5 18.4 ICL17-1 41 6.3 14.8 Average 48 6.4 16.6 7AL25-3 40 7.5 21. 5 7AL26-3 38 --- 20.4 Average 39 7.5 21.0 Average - 4 tests 43.5 6.8 18.8 600 ICL15-2 33 6.3 27.0 ICL17-3 29 7.0 29 0 Average 31 6.6 28.0 7AL26-1 34 7.5 30.0 Average - 3 tests 32 6.9 28.7 800 IC16-2 27 6.8 23.0 7AL26-2 27 6.0 24 0 Average - 2 tests 27 6.4 23.5 900 ICL16-3 28 6 3 23.0 7AL25-1 25 6.5 25.0 7AL25-2 26 7.0 025. 0 Average 25.5 6.8 25.0 Average - 3 tests 26. 3 6.7 27. 7 WADC TR 59-454 29

cP^~~~~~~~~~~~~~~~~~ ~TABLE 4 Un ~^ RUPTURE AND CREEP DEFORMATION DATA FOR TI-16V-2.5AI ALLOY (1380'F-1/2 hour-WQ; 990~F-4 hours-AC) Room Temperature Tensile Properties of Unfractured Creep Specimens Test Hardness Total Plastic Time to Reach Indicated Final Total Ultimate 0. 2% Offset Temp. Stress Rupture Time Elong. R.A. After Test Loading Def. Loading Def. Creep Deformation (hrs) Creep Def. Plastic Def.TensileStrength Yield Strength Elong. R.A. Modulus,E (~F) Specimen No. (psi) (hrs, if any) (%) (%) R"C" (%) (%) 0. 0.5 1. 0 Z.0 (%) (%) (psi) (psi) (%) () x 106, psi 600 ICL5T 140,000 >1030. 1* -- -- 40.0 2.29 1.25 --- 0,02 0.04 3.5 6.10 7.35 230,000 --- 1.0 4.0 14.0 1ALT6 ** 140,000 > 10.0* -- -- 38.4 3.78 2.80 0.2 0.45 0.8 7.3 2.22 5.02 204,000 P04,000) 1.5 12.3 13.7 7CL33T** 138,000 > 10.0* -- -- 36.6 1.52 0.53 0.4 0.95 20(est) --- 0.79 1.32 196,700 196,700 2.5 8.3 15 1 7AL18T 138,000 0.01 8.0 29.0 35.4 2.35 1.30 - --- - -- --- IALT3 ** 135,000 > 9.9* -- -- 36.5 1.66 0.86 0.9 4.0 ---- -- 0.63 1.49 186,500 186,500 3.0 18.8 14.7 lALTI ** 125,000 > 100.0* -- -- -- 1.17 0.26 9.5 78.0 ---- -- 0.59 0.85 191,200 191,200 3.2 9.7 14.2 IAL19T 120,000 > 325 * -- - -- 1.49 0.45 8.5 63.0 196 --- 1.29 1.74 202,200 198,500 3.0 14.2 15. 1 IDL34T 110,000 > 676. 1* -- -- -- 0.79 nil 26.0 144.0 ---- --- 1.07 1.07 202,500 200,500 3.5 7.4 14.5 7AL9T 100,000 > 263.8* -- -- 40.0 0.76 nil 24.0 145.0 540(est) --- 0.71 0.71 191,000 188,000 5.0 15.0 15.0 C)) 7AL8T 90,000 > 171.1* -- -- 38.4 0.66 nil 93.0 320(est) ---- --- 0.29 0.29 183,000 179,000 7.3 15.1 14.6 O 800 1CL8T 70,000 251.9 32.7 53.7 40.0 0.54 0.02 0.6 1.5 5.0 17.5 >>5.6 -- --- ------- - IDL33T 55,000 > 336.9* -- -- 41.0 0.45 nil 1.8 4.5 14.5 54.0 5.57 5.57 178,000 174,000 4.3 20.6 15.1 7BL33T 45,000 > 171. 1* -- -- -- 0.34 nil 1.7 9.5 39.5 168.5 1.99 1.99 188,800 183,000 6.5 17.5 15.2 7BL32T 35,000 > 171.2* -- -- 40.0 0.24 0.02 4.6 20.5 100.0 --- 1.21 1.23 181,000 174,000 8.8 16.0 14.6 7AL4T 20,000 > 340.3* -- -- 0. 13 nil 12.5 137. 0 --- --- 0.68 0.68 174,800 170,000 9.5 250 16. 0 1AL24T** 14,000 > 100.0* -- -- 38.3 0.11 nil 30.0 ---- ---- --- 0.30 0.30 175,000 169,000 12.0 18.9 14.9 900 1DL28T 25,000 226.0 44.3 82.0 34.7 0.23 nil 1.4 3.4 7.4 21.5 >>3.5 --- ---- - -- ---- 7AL12T 20,000 > 142.9* -- -- 36.0 0.17 nil 1.0 6.5 21.0 64.0 3.81 3.81 163,000 160,000 7.5 18.6 14.8 7CL16T 15,000 > 362.3* - -- 36.3 0.13 nil 4.4 25.0 94.0 260.0 2.57 2.57 161,500 157,000 11.0 29.5 14.7 7AL5T 10,000 > 428.5* -- -- 35.6 0.21 nil 10.0 66.0 357.0 --- 1.10 1.10 153,000 152,000 5.5 22.6 14.9 IAL21T 5,000 > 325.0* -- -- 37.0 0.03 nil 99.0 ---- ---- --- 0.37 0.37 152,000 152,000 11.0 28.0 14.9 > Greater than, > Much greater than, * Test stopped before rupture. ** Data from stress-exposure test. (est) Estimated.

TABLE 5 EFFECT OF UNSTRESSED EXPOSURE ON TENSILE PROPERTIES OF TI-16V-2.5A1 Tensile Properties After Exposure CE) Exposure Conditions Ultimate 0.2% Offset H3 Temp. Stress Time Teat Temp. Tensile Strength Yield Strength Elongation R.A. Modulus,E Hardness t Specimen No. (~F) (psi) (hrs) ('F) (psi) (psi) (%) (%) x 106(psi) R"C" 7BL36T 600 none 10 room 175,000 161,500 7.5 16.0 14.3 38.3 IDL26T none 50 room 170,700 155,900 11.0 11.3 14.3 cP~~~~~~^ IAL13T none 100 room 166,200 152,500 9.5 22.1 14.0 34.6 Un 7CL13T 700 none 10 room 180,000 163,900 10. 5 21.0 15.0 39. 5 7AL3T none 100 room 177,000 165,000 8.3 29. 7 14.7 -- 7AL1T 800 none 10 room 176,300 166,500 10.0 22.0 15.0 39. IAL14T none 50 room 170,000 -- 9.5 26.3 14.1 38.4 7BL26T none 50 room 183,500 174,00.0 8.5 14. 7 15. 3 7CL18T none 100 room 182,000 173,500 8.0 23. 4 14.8 36.7 lAL15T 900 none 25 room 166,400 159,000 11.0 25.8 14.9 36.9 7BL25T none 50 room 167,200 159,500 10.0 18.9 15.0 - <J3 p-d l- ~IDL29T none 100 room 163,500 158,500 8. 0 26.5 15. 5 37. 9 ICLIOT 600 none 10 600 142,000 120,000 8.0 22.6 13. 1 37.3 7ALIIT none 50 600 136,800 117,000 7.0 39.2 12.5 36.1 7CL23T none 100 600 148,500 126,000 7.5 29.3 12.5 36.5 ICL12T 800 none 10 800 133,800 113,700 11.0 23.2 11,9 39.9 7BL34T none 50 800 134,200 119,000 13.5 30.3 11.3 41.3 1DL25T none 100 800 132,600 112,500 12.0 28. 6 13.7 38.2 7BL31T 900 none 10 900 104,000 86,100 28.0 51.0 10. 3. 7AL1OT none 25 900 99,800 87,200 24. 0 48.0 10.3 35.5 ICLIIT none 50 900 104,000 93,500 27.0 50.8 10.6 38. 1 7CL15T none 100 900 102,800 81,400 24.0 50.4 10.5 37.4 7AL22T Inadvertently heated to 1500'F room 137,000 129,000 5.0 28. 1 14,7 for 1/2-hour - Air Cooled.

TABLE 6 EFFECT OF UNSTRESSED EXPOSURE ON COMPRESSION PROPERTIES OF TI-16V-2.5AI Compression Properties After Exposure Exposure Conditions 0.2% Offset Temp. Stress Time Test Temp. Yield Strength Modulus, E Specimen No. (~F) (psi) ( hrs ) (~F) (psi) x 106,psi 1CL94C 600 none 10 room 174,200 15.3 7BL26C none 50 room 179,000 15.4 ICL97C none 100 room 180,500 15.7 1CL98C 700 none 10 room 186,000 16.5 ICL96C none 100 room 187,500 15.4 7AL6C 800 none 10 room 186,000 17.6 1DL36C none 50 room 186,500 16.4 7CL17C none 100 room 192,000 16.3 ICLIOC 900 none 25 room 178,900 15.4 7BL34C none 50 room 183,800 16.2 IAL23C none 100 room 179,500 16.4 7CL24C 600 none 10 600 133,000 14.0 IDL27C none 50 600 133,200 13.8 7CL15C none 100 600 138,000 15. 1 _I~_CL1C 800 none 10 800 131,000 13.3 1CLI2C 800 none 10 800 131,000 13, 3 ICL93C none 10 800 131,700 13.2 7ALIOC none 50 800 136,900 13.6 IDL31C none 100 800 138,000 16.4 ICL91C 900 none 10 900 92,000 12.5 7ALIC none 25 900 103,100 12.8 IAL15C none 50 900 80,300 11.9 none 50 900 103,000 11.4 1CL92C none 100 900 105,000 12 8 WADC TR 59-454 32

TABLE 7 EFFECT OF PRIOR CREEP ON ROOM TEMPERATURE TENSILE PROPERTIES OF TI-16V-2. 5AI Norninal ______________ConditionsActual Exposure Conditions Room Temperature Tensile Properties After Exposure t-l Nominal Exposure Conditions.Total Plastic Total Ultimate 0. 2% Offset Temp. Time Creep Def. Time Stress Load Def. Load Def. Creep Def. Plastic Def. Total Def. Tensile Strength Yield Strength Elong. R.A. Modl~u.E Hardness 0) ('F) (hrs) (o) Specimen No. (hr.) (psi) () (70) %) %P) (P) Ws M x 1,psi RSC Hj 600 10 0.2 ICL7T 10.0 118.000 0.91 0.09 0.18 0.27 1.09 174,300 174,300 5.0 16.4 14.3 38.8 W7J 0.5 IALT3 9.9 135.000 1.66 0.86 0.63 1.49 2.29 186.500 186.500 3.0 18.8 14.7 36.5 (JI 1.0 7CL33T 10.0 138.000 1.52 0.53 0.79 1.32 2.31 196,700 196.700 2.5 8.3 15.1 36.6 0 2.0 IALT6 10.0 140,000 3.78 2.80 2.22 5.02 6.00 204,000 204.000 1.5 12.3 13.7 38.4,41 100 0.2 IDL36T 100.0 89,000 0.60 nil 0.17 0.17 0.77 177,700 167.500 9.0 13.5 13.3 39.5 0.5 7CL19T 100.0 110.000 0.84 0.04 0.40 0.44 1.24 184.000 182,500 5.0 15.4 14.0 39.6 1.0 IALTI 100.0 125,000 1.17 0.26 0.59 0.85 1.76 191,200 191,200 3.2 9.7 14.2 2.0 7CLT32 100.0 130.000 1.14 0.28 0.72 1.00 1.86 199.800 199.800 2.0 9.1 13.9 37.3 ICL26T nil 135,000 Broke on loading. 700 10 0.2 7CL9T 10.0 75,000 0.51 nil 0.27 0.27 0.78 180.000 171,200 8.5 20.0 14.4 38.4 1.0 IAL32T 10.0 100,000 0.81 0.07 0.84 0.91 1.65 176.000 176,000 8.5 20.5 14.3 39.6 7AL35T 10.0 106,000 0.83 0.10 0.98 1.08 1.81 186,000 186.000 6.5 16.0 14.2 100 0.5 1BL34T 100.0 57,000 0.41 nil 0.61 0.61 1.02 179,000 169,000 8.8 21.8 16.5 1.0 7AL19T 100.0 80,000 0.61 nil 1.28 1.28 1.89 186,000 181,000 7.8 20.3 14.4 800 10 0.2 7CL34T 9.9 23.000 0.19 nil 0.26 0.26 0.45 184,000 174,000 9.0 18.9 15.0 39.5 0.5 IAL22T 10.0 44,000 0.35 0.01 0.58 0.59 0.93 169,100 161,500 5.5 24.7 14.6 39.5 (p 1.0 ICL6T 10.0 61,000 0.50 nil 1.15 1.15 1.65 177,500 171,300 8.0 24.9 14.2 40.4 2.0 7BL29T 10.0 76,000 0.52 nil 1.85 1.85 2.37 181,500 175,000 7.5 14.9 16.3 39.4 100 0.2 IAL24T 100.0 14,000 0.11 nil 0.30 0.30 0.41 175,000 169,000 12.0 18.9 14.9 38.3 0.5 7CL22T 100.0 22,000 0.15 nil 0.48 0.48 0.63 182,700 174,900 8.0 14.3 14.7 39.5 1.0 IDL35T 100.0 35,000 0.28 nil 1.06 1.06 1.34 179,800 171,500 10.5 13.3 14.9 40.4 2.0 IAL16T 100.0 50,000 0.38 nil 1.84 1.84 2.22 177,000 171,500 9.5 21.2 15.1 40.5 900 10 0.2 ICL2T 10.0 10,000 0.10 nil 0.21 0.21 0.31 172,600 160.000 8.0 16.0 14.3 38.9 0.5 7BL27T 10.0 18.000 0.17 0.01 0.50 0.51 0.67 175,000 167,000 9.5 21.0 14.6 40.0 1.0 7CL2IT 10.0 24,000.0.21 nil 0.90 0.90 1.11 173,800 166.300 8.0 16.5 14.1 38,7 2.0 7CL36T 10. 0 29,500 0.28 nil 1.45 1.45 1.73 185,000 177,800 8.5 11.6 14.6 ICL28T 10.0 31,500 0.28 0.03 1.87 1.90 2.15 166,000 160,000 8.0 23.6 15.8 100 0.2 7CL25T 100.0 5.000 0.04 nil 0.21 0.21 0.25 170,500 164,200 7.5 20.0 15.7 37.7 0.5 IAL5T 100.0 9,000 0.11 nil 0.45 0.45 0.56 163,200 157,000 9.5 34.2 15.8 37.3 X.0 7CL3ST 100.0 14,500 0.13 nil 1.07 1.07 1.20 170,000 163,900 10.5 20.6 14.9 38,5 2.0 ICLTI 100.0 19,000 0.22 0.01 1.84 1.85 2.06 168,000 163,000 10.0 24.3 14.6 37.9

TABLE 8 EFFECT OF PRIOR CREEP ON ROOM TEMPERATURE COMPRESSION PROPERTIES OF T-i-bv-2.SA I Comprseeion Propertlee Actual Exposure Cooidtlons After Exposure No Enal Exposure Copditfam Total Plasttc Total 0.2ZsOffset Temp. Time Crip Dol. Time Stres. Load Del. Load Doi. Creep 0.1. Plaetic De. Total We. Test Temp. Yield Strength Modulus, E (IF) itre) J S icmes No, (bre) Wp.L) ___ __ _) (I J ) (!) (Pci) a lo6(psi) 600 10 0.I 7BL28T 10.0 125.000 1.01 0. I5 0.24 0.39 3.25 room 156.000 13.9 0.5 7CL3OT 10.0 131.000 1.47 0.46 0.39 0.85 1.86 room 139.500 15.3 1.0 7CL26T 10.0 138.000 2.30 1.30 0.54 1.84 2.'84 room 140.500 15.3 IAL23T nlI 139,000 Fractured on loading. 2.0 IAL35T 10.0 140.000 2.35 1.75 Fractured immediately after loadlng. 7AL14T 10.0 140.000 2.3(e.t.) 1.7(est.) 0.69 2.4(est.) 3.O(O~t.) room 117.000 15.8 100 0.2 IALZ5T 100.0 91,000 0.65 nil 0.24 0.24 0.89 room 176,000 17.0 0.5 IALT4 100.0 114.000 1.03 0.25 0.59 0.84 1.62 room 165.000 18.2 1.0 IBL26T 100.1 131,000 2.07 0.16 1.19 1.35 3.26 room 137,000 14.9 2.0 IALT26 nil 137.750 Fractured on loading. 700 10 0.2 IBL24T 10.0 80,000 0.58 nil 0.34 0.34 0.92 room 151.000 15.3 1.0 7BL2T 10.0 105.000 0.86.4l 0.99 0.99 1.85 room 144.000 t5.7 100 0.5 7AL17T 100.0 57.000 0.44 nil 0.59 0.59 1.03 room 172.500 14.4 1.0 ICL31T 100.0 80,000 0.62 0.02 1.26 1.28 1.88 room 175,500 14.3 800 10 0.2 IALTII 10.0 23,000 0.18 nil 0.20 0.20 0.38 room 175.000 15.9 0.5 7CL27T 10.0 37.449 0.29 0.04 0.39 0.43 0.68 room 179.000 16.2 IALTS 10.0 50.500 0.38 0.05 0.61 0.66 0.99 room 174,500 35.7 1.0 IAL27T 10.0 61.000 0.48 nil 1.00 1.00 1.48 room 173,000 16.4 2.0 IBL28T 10.0 76,500 0.64 0.07 1.73 1.80 2.37 room 153.000 15.2 7AL2OT 10.0 77.000 0.66 0.02 2.54 3.56 3.20 room 160.900 14.6 100 0.2 IAL36T 100.0 14,000 0.32 Ail 0.28 0.28 0.40 room 170,000 15.8 0.5 7CLT31 100.0 22,000 0.17 nil 0.55 0,55 0.72 room 201,000 16.8 ICL29T 100.0 22,000 0.30 ni1 0.32 0.32 0.42 room 176.000 16,2 1.0 7CL5T 100.0 35.000 0.25 nil 1.18 1.18 1.43 room 177,000 16.0 2.0 IALTI2 100.0 51.000 0.41 nil 2.16 2.16 2.57 room 176.900 16.2 900 10 0.2 IALT7 10.0 10,000 0.08 oil 0.18 0,.8 0.26 room 172.000 15.8 0.5 7CL29T 10.0 18.000 0.18 nil 0.49 0.49 0.67 room 150,500 36.4 1.0 IAL28T 10.0 24,500 0.23 all 0.98 0.98 1.23 room 170.200 16.7 2.0 IALTIO 10.0 30.500 0.28 0.04 1.88 1.92 2.16 room 171.000 16.1 100 0.2 IAL31T 100.0 5.000 0.05 nil 0.23 0.21 0.26 room 180.000 17.2 0.5 7CL28T 100.3 9,000 0.08 nil 0.47 0.47 0.55 room 179,200 15.5 1.0 IALT9 100.0 14.500 0.15 nil 1.12 1.l2 1.27 room 176.200 13.3 2.0 7CL8T 100.0 19,500 0.19 0.01 2.13 2.12 2.30 room 161,000 36.7 WADC TR 59-454 34

U n H L,. TABLE 9 EFFECT OF CREEP EXPOSURE ON MECHANICAL PROPERTIES OF TRANSVERSE SPECIMENS OF TI-16V-2.5AI Exposure Conditions Tensile or Compression Properties After Exposure Plastic Total Total Ultimate 0. 2% Offset Temp. Time Stress Load Def. Load Def. Creep Def. Plastic Def. Total Def. Test Temp. Type Of Tensile Strength Yield Strength Elong. R.A. Modulus,E Specimen No. (IF) (hrs) (psi) (%) (%) (%) (%(%) (F) Test (psi) (psi) (%) (% () x 106(psi) IBT-TI As produced. --- -- -- -- -- -- room Tensile 165,200 152,000 6.5 18.6 14.2 IBT-TII 600 10.0 none -- -- -- -- room Tensile 170,000 156,000 5.8 12.0 15.2 IC-TI 600 10.0 132,000 0.62 1.49 0.62 1.24 Z.11 room Tensile 186,000 186,000 1.5 11.8 14.0 IBT-C5 As produced --- -- -- -- -- room Compression --- 175,000 - -- 18.6 IBT-C7 600 10.0 none -- -- -- -- - room Compression --- 175,000 - -- 16.7 IBT-T25 600 9.9 132,000 0. 80 1.72 0.84 1.64 2.57 room Compression --- 127,000 - -- 14.9 tJO <JI

^q ~~~~~~~~~~~~~~~~~~~~~~TABLE 10 W ~~~~~~~~~~~EFFECT OF P:RIOR CREEP ON ELEVATED TEMPERATURE TENSILEPROPERTIES OF TI-16V-2.5SA1 U'l \0 ___________________________~~~~~~Actual Exposure Conditions_________________ _____________Tensile P~roperties After Exposure_____________ I Nominal Exposure Conditions~Total~Plastic ~ Total ~ Ultimate 0. 2% Offset 1^ ~~~Temp. Time Creep Del. Time Stress Load Def. Load Del. Creep De~. Plastic Del. Total Del. Test Temp. Tensile Strength Yield Strength Elong, R.A. Modulus,E Hardness {J1 ( ~F) (hrs) (go) Specimen No. (hrs) (psi) (%) (%) (%)!%) (%) ('F) (psi) _____(psi) ( %) (%) x IO6(psi) R"C" 600 10 0.2 1DL27T 10.6 130,000 1.79 0.70 0.27 0.97 2.06 600 143,700 138,500 8.0 17.3 12.6 36.2 0.5 7CL7T 10.0 131,000 1.40 0.49 0.46 0.95 1.86 600 151,000 145,000 5.8 30.0 12.6 37.2 1.0 7BLIT 10.0 137,889 2. 15 1. 17 0.48 1.65 2.63 600 151,000 149,000 15.0 28.9 12.8 58.7 2.0 7AL16T nil 140,000 1.34 0.28 Ruptured on loading. 100 0.2 IAL30T 100.0 91,000 0.65 nil 0.20 0.20 0.85 600 144,000 125,000 7.3 24.5 14.2 37.6 0.5 7CL4T 100.0 114,000 0.89 0.08 0.48 0.56 1.37 600 156,000 145,000 6.0 21.3 12.0 39.9 1.0 IBL31T 100.0 131,000 2. 15 1. 16 1. 14 2.30 2. 15 600 155,500 --- 3.0 23.5 12.4 800 10 0.2 7CLIOT 10.0 23,000 0. 18 nil 0.20 0.20 0.38 800 131,000 113,000 10.0 23.4 12.0 39. 1 0.5 IBI.,3T 10.0 44,000 0.33 0.02 0.55 0.57 0.88 800 128,000 116,000 9.5 27.7 11.2 37. 00 ~.,..~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~3. 0^ ~~~ ~ ~~~1.0 IAL33T 10.0 61,000 0.47 0.02 1.35 1.37 1.82 800 132,000 115,000 10.0 43.0 11.3 39.1l 2.0 7AL13T 10.0 76,500 0.50 nil 2.39 2.39 2.89 800 130,000 118,000 12.0 30.3 1.2 46 100 0.5 ICL25T 100.0 22.000 0.20 mil 0.57 0.57 0.77 800 132,000 115,000 10.5 300 1. 2.0 7AL32T 100.0 51,000 0.39 nil 2.21 2.21 2.70 800 138,000 125,000 7. 190 26 900 10 0.2 1CL13T 10.0 10,000 0. 10 nil 0.20 0.20 0.30 9015009,0 82 5. 05 3. 0.5 7CL6T 10.0 18,000 0.06 nil 0.44 0.44 0.50 900 107,400 8,0 05 5. 08 3. 1.0 IALT2 10.0 28,000 0.24 nil 1. 10 1.10 1.34 900 107,800 99,300 190 4. 1.7 33 2.0 IBL25T 10.0 30,500 0.27 nil 1.59 1.59 1.86 900 108,000 9,0 55 4. 07 3. ioo 0.5 7AL36T 100.0 9,000 0.10 nil 0.44 0.44 0.54 900 110,000 87,500 16.5 49.0 11.9 1.0 7AL31T i 00.0 14,500 0.11 0.01 1. 14 1. 15 1.25 9013,09,00 7. 468 11 2.0 ICL23T 100.0 19,000 0.19 nil 2. 11 2.11 2.30 900 10501500 1. 03 i.

TABLE 11 tj EFFECT OF PRIOR CREEP ON ELEVATED TEMPERATURE COMPRESSION PROPERTIES OF TI-16V-2.5AI Compression Properties 1-H ___________Actual Exposure Conditions After Exposures Wl Nominal Exposure Conditions Total Plastic Total 0.2% Offset Temp. Time Creep Def. Time Stress Load Def. Load Def. Creep Def. Plastic Def. Total Def. Test Temp. Yield Strength Modulus,E ^nO ('F) (hrs) (%) Specimen No. (hrs) (psi) (%) () () () (%) (~F) (psi) x 106(psi 1 600 10 0.2 IAL34T 10.0 118,000 1.05 0.23 0,22 0.45 1.27 600 101,000 14.3 7 r0.5 IBL27T 9.9 132,000 2.20 1.97 0.56 2.53 2.76 600 100,000 13.8 1.0 7CLlT 10.0 137,500 2. 10 1.11 0.58 1.69 2.68 600 105,000 14.3 100 0.2 IBL33T 100.0 91,000 0.66 0.05 0.20 0.25 0.86 600 >114,000 15.2 0.5 7CL3T 100.0 114,000 0.86 0.04 0.45 0.49 1.31 600 127,000 13.4 1.0 1BL31T 99.8 131,000 2.34 1.32 1.22 2.54 3.56 600 110,000 13.3 800 10 0,2 7CL11T 10.0 23,000 0.18 0.01 0.24 0.25 0.42 800 125,400 12.5 W() 0.5 7CL12T 10,0 44,000 0.38 nil 0.54 0.54 0.92 800 123,000 12.3 -13^~ ~1.0 IAL29T 10.0 61,000 0.43 nil 0.98 0.98 1.41 800 113,000 12.8 2.0 IBL32T 10.0 77,000 0.57 nil 2.03 2,03 2.60 800 116,000 13.3 100 0.5 7AL33T 100.0 22,000 0. 17 nil 0.51 0.51 0.68 800 123,000 13.4 2.0 ICL22T 100.0 51,000 0.38 nil 2.07 2.07 2.45 800 123,000 12.5 900 10 0.2 ICL14T 10.0 10,000 0.10 nil 0.23 0.23 0.33 900 108,000 11.9 0.5 7CLT2 10. 0 18,000 0.17 nil 0.50 0.50 0.67 900 118,000 12.6 ICL34T 10.0 18,000 0.16 0.02 0.52 0.54 0.68 900 92,400 11.1 1. 1 0 IBL35T 10,0 24,500 0.23 nil 0.79 0.79 1,02 900 101,300 12.5 2.0 1BL29T 10.0 30,500 0.25 0.02 1.55 1.57 1.80 900 97,000 12.1 100 0.5 7AL34T 100.0 9,000 0. 10 nil 0.50 0,50 0.60 900 98,000 9.9 1.0 ICL24T 100.0 14,500 0.09 nil 1.09 1.09 1. 18 900 96,500 11.0 2.0 ICL21T 100.0 19,000 0, 16 nil 2.26 2,26 2,42 900 97,500 11.7

TABLE 12 EFFECT OF UNSTRESSED EXPOSURE ON TENSION-IMPACT PROPERTIES OF TI-16V-2.5AI Exposure Conditions Tension-Impact Properties after Exposure Temp. Time Test Temp. Tension-Impact Elongation R.A. (0F) (hrs) Specimen No. (0F) Strength, ft-lb (%) (%) 600 10 ICL18-1 room 43 6.0 28.0 50 ICL20-2 room 48 7.0 23.0 100 7AL27-1 room 30 5.5 15.0 700 10 7AL29-3 room 27 1. 5 2 0 800 10 ICL19-1 room 53 7.5 26.0 7AL28-2 room 39 1.7 13.0 50 7AL27-2 room 38 5.5 19.0 100 7CL28-3 room 45 6.5 15.0 900 10 7AL27-3 room 35 5.3 15.0 7AL30-1 room 39 4.5 20.0 50 ICL18-2 room 58 5.5 19.0 100 1CL20-1 room 58 8.5 21.0 600 10 7AL30-2 600 34 7.0 31.0 50 7AL28-1 600 27 5.5 29.0 100 ICL20-3 600 29 6.5 23.0 800 10 1CL19-2 800 29 6.3 23.0 50 7AL29-1 800 30 6.0 35.0 100 ICL19-3 800 28 6.8 18.5 900 10 ICL18-3 900 26 6.3 43.0 50 7AL30-3 900 30 5.5 26. 0 100 7AL29-2 900 Z4 3.3 24.0 WADC TR 59-454 38

TABLE 13 tj EFFECT OF PRIOR CREEP ON TENSION-IMPACT PROPERTIES OF TI-16V-2.5AI Actual Exposure Conditions Tension-Impact Properties after Exposure 3 Nominal Exposure Conditions Total Plastic Total Temp. Time Creep Def. Time Stress Load Def. Load Def. Creep Def. Plastic Def. Total Def. Test Temp. Tension-Impact Elongation R.A. (~F) (hrs) (%) Specimen No. (hrs) (psi) (%) (%) (% (%) (%) (~F) Strength,ft-lb (%) (%) tU,0 600 10 0.2 7AL15T 10.0 118,000 1. 10 0.28 0.30 0.58 1.40 room 32 3.3 17.0 0.5 7AL21T 10.0 131,000 2.30 1.30 0.85 2. 15 3.15 room 25 3.0 21.0 U1 14 1. 0 ICL33T 10. 0 137,500 3.45 2.40 1. 17 3.57 4. 62 room 20 2.3 3.9 2.0 7AL18T nil 138, 000 2,35 1.30 Ruptured just after loading. - - 700 10 0.2 ICL32T 10.0 75,000 0.54 nil 0.31 0.31 0.85 room 52 7.2 22.0 1.0 1CL35T 10.0 105,000 0.86 0.10 1.09 1.19 1.95 room 31 4.0 22.0 800 10 0.5 ICL30T 10. 0 44,000 0.36 nil 0.74 0.74 1. 10 room 28 3.0 24 0 1.0 7AL24T 10.0 61,000 0.50 0.04 1.08 1.12 1.58 room 26 2.0 21.0 W^}~ ~ z~2.0 IBL36T 10.0 77,000 0.59 0.02 2.17 2.19 2.76 room 32 4.3 29.0 900 10 0.5 13C36T 10,0 18,000 0. 16 nil 0,48 0.48 0.64 room 43 9.0 17.5 1.0 7AL23T 10,0 24,500 0.23 0.01 0.97 0.98 1.20 room 36 4.7 23.5 2.0 ICL27T 10.0 31,500 0.25 0.01 1.80 1.81 2.06 room 47 6.5 13.7 600 10 0.2 IBL5T 10. 0 119,000 1.00 0.25 0.23 0.48 1.23 600 27 23.0 0.5 7BL9T 10.0 130,000 1.44 0.87 0.69 1.56 2.13 600 34 1.0 19.0 1.0 IBLIIT 10.0 137,000 3.13 2.10 2.13 4.23 5.26 600 37 1.0 16.0 900 10 0.5 7BL15T 10.0 18,000 0.16 0.01 0.49 0.50 0.65 900 24 2.3 8.0 1.0 IBL3T 10.0 24,500 0.22 nil 0.85 0.85 1.07 900 31 2.5 8.0 2.0 7BL20T 10.0 31,500 0.25 nil 1.67 1.67 1.92 900 42 5.0 25.0

I -TI rT26 -jJ $g J~ ~SECTION A iTI' SECTION B T26 SECTION C SECTION D a P 0^ j — ~IC —- h t^ICL-TI- C( ~a IAL-TI-12 C C # i, I Il" <-l<-l(-lgq l I (L-~gIII g 3 2 ======= ==== -ICL-T8-13 I DI-24 U- SHEET 0084-1I AL-TI3-24 I BL-T36 I C- =CL-T14 - 2 _ I I AL-T25-36 ~ —------- - DL-T25-36 L 11......., r I I 11 1 1 C: r" v} W -7AL-TI-12 - 7CL-TI-12 7 BL —T'-24 C~~~~~'I C~ SHEET 0084 - 7 ------- 7AL-T13-245 - 7D (Om MI I I lcI irE^ I I l I I 7BL-T25-36 7 C L -T25-36 f m -7 AL-T31-36 A L=. SECTION A SECTION B SECTION C SECTION D SCALE fLL, * Lw FIGURE I SAMPLING PROCEDURE FOR T; 16 V - 2.5AI ALLOY ONCHES)

Exposure Spec. 0.530 (+ Q Q3) Tensile Spec. 0. 500 C)'- f^-15/I^ H- 4. _______________^^_15/16H c1 ~ - 4. 8~^T __I I 7^ - -x M Appr ox. -/ ~y Grind last 1/32 each edge, \Grind longitudinally 5/32 D 3/8 D _____________~_________ _ ~22 Tensile or Creep-Exposure Specimen I R 0. 200 ~ 0. 003) t ^ ^ ^_________________ ____ \ I -l1 /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 A_-1- _ 0. 064 INCHES ~ _____ 2-3/4 Compression Specimen Figure 2, - Details of Test Specimens (Tension-Impact and Compression Specimens Designed to be Cut from Creep Specimens after Exposure).

180 0 0 170 N S ~ 160 - ~ \Ultimate 150 L..... N Yield N 140 — ~~~~ 130 120 1 I I' I~ I ~I I 0 130 o100 ~~ ~ I I I \_ ~ 20 A 60 500 30 1 30 20 o 8 ~ ~~-~ ~~^ ~70~~~ ~ ~ ~ ~~0 ~ 40 410 2~Elong tiO n 0 90 o/ o Figure 3. - Effect of Test Temperature on Tensile Properties of Ti-16V-2. 5Al. WADC TR 59-454 42

180 170 160 150 N\ \C 0 120 90 0 80 U, N 70 0 U 60 50 40 30 20 10 0 100 200 300 400 500 600 700 800 900 1000 Test Temperature-~F Figure 4. - Effect of Test Temperature on Conmpression Yield Strength of Ti-16V-2.5A1. WADC TR 59-454 43

601 - 0 50 40 0 0 0 30 0 0 10 o H0 - - - ~ -~ - 01 0 100 200 300 400 500 600 700 800 900 30 [VTT. -~ C_ 0 T est Te mperature - F 10 Ps of Ti-1VWADC TR 59-454 44 0 100 200 300 400 500 600 700 800 900 Test Temperature-0F Figure 5 - Effect of Test Temperature on TensionImpact Properties of Ti-16V-2.5Al.

140' (8'. 2A 1 - -- -- 0% ~(81 0)11 130 120 ~ Code'S ^0~ i- Rupture a ( )oElongation on Rupture llO ~ 0 0.2 O A 0.5 Creep 1. 0 Deformation-% est) 10 __ 2_ _ _ - 0 (e at) 80 I I I I I I I I I 1 1 I I I I I III I I I I 1 1111 1 I I 1 r. o(32.) 90 ~- -~ - ~ -- - \( 0. 2% 0. 5% so 600 70 ~01 i 10 100 1000 Time-hours 80 \0(32_ 7)__70 o~ 60 O A 800F 30 ~ - " -, 01 00 1000 Time-hours 30 i ^ ~ I. "' 2 5~- - - - - ~- I R u p 9000e ________ ___ _l___ll.. I Al II and 900eF. WADC TR 59-454 45

Prior Creep at 600~F Prior Creep at 800'F Prior Creep at 900F 230.. 230 230 1030 Utj ~~ g, 2 _o___ __~ 220 220 220 210 __ __ _ __ __ _ ~ 1 ~ 210 ~ 210 Ha 5676'"n 325 0 10 (1 2I) 200 ~ ~ ~ ~ -~ - - 200- 200 (_n 2.0 o 200,.0o 190 Cp100 10 n _ 026410 171 ^~P ~ ~o 0 10 180 171 180 0 180 -100 -,~ __.k~~~~~~~~~~~0 0 CU 340 1' 170 171 170 I -362 160 160 ~ ~ 160 0 o 325 150 5 0 150 ~ 150 0 0.0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 0 1 2 3 4 5 o 200 - 325 200 200 0 o o 100 10 190 __ o _ 190 - 190 o4 o 40 171 ~0', ~~~ 264 1 0 180' Code 180 180 U' 171 337 171, As treated O 0 B- 170 - 170 0 -0340 ~- - ~ 170 Figures next to test points are 100 100 prior creep times in hours. 14 160 160 - 160 362 0 0. i I 28 0 150 150 150 ~ 4 I I. [ 140 140 140. - a 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 0 1 2 3 4 5 ^ ^ ^"o ~ 10 10 I I' C,, 0o 0 0 1 2 3 4 5 6 7 8 0 1 2 3 4 5 6 0 2 3 4 5 Total Plastic Strain-% Total Plastic Strain-% Total Plastic Strain - Figure 7. - Effect of Deformation in 10 hour to 1030 hour Creep Tests at 600', 800', and 900'F on Room Temperature Tensile Properties of Ti-16V-2.5A1.

Code 0 600~F o 2 00 0 700~F Exposure c. I A 800~F Temperature ^o o 10_ o9000F ____ k o 190 Jo,0C Unexposed -I I I 800 a 1 I 8, Au 0 0 _ 170 I I 7000F II 160 __ ~_ ~~ I I 900"F - 50;^ 140^ ^~^___ ____________ ____ __________________800"F 0 o 20 30 40 0 60 7 700~F 20[ o 160 I oE 14 i ~~ 600"F O 150 o W4 TR 140 130 _...._ 0 10 20 30 40 50 60 70 80 90 100 fd w 0 1 20 30 40 50 60 70 80 90 100 Exposure Time - hours Figure 8. - Effect of Unstressed Exposure on Room Temperature Tensile Properties of Ti-16V-. 5AI. WADC TR 59-454 47

I 190" o o o _______________ ___-0_ 180 -d 0 ^ 1700 ~ ~ ~ ~ ~ I 0 1760 \ 150 0 100 200 300 400 500 600 700 800 900.1800 C0 0 0 o o o 160 O a) r 1 E r 150 _~_~ _~_ ______ __.1' 140~ 0 100 200 300 400 500 600 700 800 900 9 200 E~~ _ _______x o u o 0 o'I ~ 190 ~ ~ ~ ~ ~. __ _ 00 o 170 0 160 1_ 0 100 200 300 400 500 600 700 800 900 Exposure Temperature-oF Figure 9. - Effect of 100 Hours Unstressed Exposure on Room Temperature Tension and Compression Strengths of Ti-16V-2.5A1. WADC TR 59-454 48

150.0 Code10 800"F 0 600~F Exposure Temperature ~ 0 900*F Test Temperature ~ 110 ~ ~~~~~ E~^ ~~~~90 90130 130 ~ ~ ~ ~ ~ ~ ~~~1~ i I I 0 ~b12 ~ T!900' 800OF0F AA 800]F "0 ", Temperature 9 201 1 I I 1 i I 1 [ —-T-900~F I1 "~^~^ I I I I I I I iOO"F 900iF a A 1 20 30 40 50 60 70 80 90 100 F Figure 10. Effect of Unstressed Exposure on Elevated Temperature Tensile Properties of Ti-16V-2, 5A1 0WADC TR 5-454 49

210. —-. 200 U) I I I I I I I I I 8000F I ^ ~~~~~~~~ ~ ~ o 180...... -.. y 8, 0 Co900 de tt 170J1))/< F ___ _ 160600F 0 O A 800~F Temperature 130 ___ ~ ___ ___ X0_Code 10a 800F Temperature 0 10 20 30 40 50 60 70 80 90 100 Exposure TimUnexposed F 120 Unst ed E ure oom Temp Compression Yield Strength of Ti-16V-2.5A1. WADC TR 59-454 50 0 0 10 20 30 40 50 60 70 80 90 100 Exposure Time-hours Figure I1. - Effect of Unstressed Exposure on Room Temperature Compression Yield Strength of Ti-16V-2.5A1. WADC TR 59-454 50

140._____. __ _ l l 800_F a-, a600~ F 130 -TsT ~eau 0 100 ~ 1 9000F 9 0, 90 b1 80 v 70 r-4 r 60 0 o 40 Code 0 600~F) Exposure Temperature A 800~F and 30 ___ 900F Test Temperature 20 10 - ~ 0 10 20 30 40 50 60 70 80 90 100 Exposure Time-hours Figure 12. - Effect of Unstressed Exposure on Elevated Temperature Compression Yield Strength of Ti-16V-2, 5A1. WADC TR 59-454 51

10hr Prior Creep at 600*F 100hr Prior Creep at 600"F a I IO' 210,, 2 10 ~\ h ~ 200 200 O r4o m O 4)' 190 190 0 0 O/ 0~0 2r 10 7 _ 170__ 17~ 0.o 0 2.0 3o 0 0 1.0 2. 0 3.0 2 10.... 2 101 ~o I Io Tension 200 200 O Tension 190 ______190 0 11,80 180 170 170 1/' Code 1 1600 _____ -O-Tension 160 ~ I A < —A — Compression # 9 ^Jp Unexposed V~ 150 4- 150 o 140 -- 140 \ H\ Compression Compression 130 ~~ 130 o I 110 _.... 110 ~ 0 1.0 2.0 3.0 0 1.0 2.0 3.0 I 0,, 10 I 0 ~, 5 55 0 O 0 0 1.0 2.0 3.0 0 1.0 2.0 3.0 Creep Deformation-%o Creep Deformation -% Figure 13. - Effect of Prior Creep Exposure at 600~F on Room Temperature Tension and Compression Properties of Ti-16V-2.5A1. WADC TR 59-454 52

g c5 f9St,-69:I. DH aVW *'VS*Z'-A91 -TI Jo s9alpradoJd uotssa;tduJo pue uoTsuaLU, a9Tnl;dtuuL Uwool aq 0 uo jo009 e nJnsodx3-dao3D uT pa9q3ave UTilS DTllsed t1eOl, JO 3aJJ3 -' *I1;nBlj o/-uT'ei.S 314SeId Ie0OJ, 0 9 0 S Ob 0*E O0 0o- 0 I 0I 0*9 0^ 0_ ______________01 UOISUXL I~~~~~ A I I \ ~|~'l 01- "................. I ~ oo'01 - 0 ~ OZI 0*9 0OS 00' 0' OZ 001 0.....___~ 0 1 1 OI I1 001 \ ________________________.___~ O -9 = 001 I I \ \ - __00 I ___ -~01 UOTS s~ \d w/ o opo3 m, X/i a X' _ 0LI _.___ \ 091 08 0 061 0 xt 01 - 0 0*9 0o' 0*o -1 0. o 0* o 01 0........ ^~1091 L..i. o L ~ 015o..... ~~~~~i...... /~~081 I o'q O'Ij O'P q oot ooz o~

10hr Prior Creep at 7000F 100hr Prior Creep at 700~F 210 2 Z10 c' 200 200 h o si O o 190 190 I 180 0~0 ~ 180 ~~ ou 170 170 ~r160 160 150 150 0 1.0 2.0 0 1.0 2,0 210 210 P-4 o 200 200 190 190 1 90 Tension Tensi A o Tension 48 180 180.t 170,a2~ J _ l 170,X -o Compression I'Code 150 150 -0- Tension - -a- - Compression 1H A 0 1 p4 Unexposed 140 17O Compression 40 o I 1300 o 130 - 0 1.0 2.0 0 1.0 2.0 100 9 10 Creep \ eformation_% Creep Deformation-% Figure 15. - Effect of Prior Creep Exposure at 700~F on Room Temperature Tension and Compression Properties of Ti-16V-2, 5A1, WADC TR 59-454 54 i 1.0 2.0 3 1.~0 210 Creep Deformation-% Creep Deformation-l W ADC TR 59-454 54

10 hr Prior Creep at 800~F 100 hr Prior Creep at 800~F 210 210, 200 200 k ^ 4h- ~ 190 190 - o 1 180 180 r- o1 0.-~- — 0 F0. O8Z170 ~0~- 170 o 160 160 0 1,. - 2- 0.3. 0 0 1.0 2.0 3.0 la 2101 210 a 0, 200 ~~~ 200 bUl — A W 190 190 2 180 | \ ~ ~ Tension 180 ~\ ~. _l _^_ 1 -180 Tension 180 < Compression h 160 O~~ A | 160 Cod _ ~ _I -0- Tension r- Compression 5 j A 0 — a — Compression H:150 1501 -,f Unexposed o 140 I1~140 1~ 15 15 i 40 10 _ 10-0 ~ ( U 00- _ _ _ _ _ _ _ _ _ _ 0o1 o 0 ___ 0,,o.. 0 1.0 2.0 3.0 0 1.0 2.0 3.0 Creep Deformation - % Creep Deformation - % Figure 16. - Effect of Prior Creep Exposure at 800~F on Room Temperature Tension Properties of Ti-16V-2. 5A1. WADC TR 59-454 55

10 hr Prior Creep at 900~F 100 hr Prior Creep at 900~F 210 210 200 200 ---- - o190 -_______ - 190 - I —I -Code ~: o 3 190 -O- Tension "ka^= o^ | O —A — Compres sion bc 180 ____ 180 p, Unexposed 0 l?0 g/ o< O170' " 1 170 0 O - 0-4 0 0 0 o r 160 160 I --., 150 150 1 O _ _ 210 210 o o o' 200 200 k 190 190.l V 180 180 A1 a2a. Comp sion mpression A 170R -___ Compresson ted ^ ~~Tension 0 I O \/ ~~ ^ ~Tension~)o I i50'150 0 c 140... ~~ 1 140 15 I 1 15- i~ 5o oo.~ O ~ -0- O -0 o 0 0 0 1.0 2.0 3.0 0 1.0 2.0 3.0 Creep Deformation-% Creep Deformation - % Figure 17. - Effect of Prior Creep Exposure at 9000F on Room Temperature Tension and Compression Properties of Ti-16V-2, 5A1, WADC TR 59-454 56

LS: Tf9 -6S9 HI DI V'.,'TV'Z-A91"1- x JO soxlaodoJd uoTBssaoduoD pup uoTsuol ainIPBadtujL, LuooH uo daajo %o o0 -10 passaJlsuf JaoqlTa 3e006 01.009 jv aonsodx: inoH-001 Jo 1a9JJ3 -'81 9.nOTE Xo-ain3aJaduJ., aInsodx~ 006 008 OOL 009 009 00' 0o 00Z 001 0 M i0 0 o':~ /, _ _ o______ 1~_ __.o - o_ _ __.. i 01 006 008 OOL 009 009 OO 00? 001 0 091 o a oCD ~ ~ ~~~ ~ ~ ~~V~~~ 0 9 1 061 0 00? 006 008 OOL 009 009 OO1 00C 00? 001:0 He OLI " ~ \ ~ ~ ~ V -~~ 08 1 C Cd 0O pasodxauf 5 ~~apoo ~CD C _ 081 006 008 OOL 009 009 00t 00 00? 001 0 yV - 011 \_____ -/_ _ ~___ 081 En 08Q\'I I, I ( I l0.. I.,J I I,-~

lOhr Prior Creep at 6000F 200. ~4 1o 190 Oi < o 190 ~~ 200 0',, 180 ob a. h 170 (I I g 160 1501 0 1.0 2.0 200 Tension 0 190 o 0, 180 CODE!iur 17 — /___ E o - e o tomrCreep Total Plastic b 170 En \1 Strain Strain,, 160 -\___ Tension o * \ A A Compression 150 415 o\ Tp - Unexposed C 140 Compression 130 o O A 0 0120 0 1.0 2.0 Deformation - % Figure 19. - Effect of 10-hr Creep Exposure at 6000F on Room Temperature Tension and Compression Properties of TRANSVERSE SPECIMENS of Ti-16V-2,5A1. WADC TR 59-454 58

10 hr Prior Creep at 6000F 100hr Prior Creep at 600~F m 170 1 170 ~~ 0 160 160 5I 0 ^ 150 ~o ~ 150O 00 140,d 140~ 0'4^ Code E 130 -O- Tension 130 H -__A —Compression w po, Unexposed o 120 120 o 110 110 0 1.0 2.0 0 1.0 2.0 160 - 160 1 /Tension o 150 150 Tension 0 /o 0 140 140 A l _ I _ - L- ~ ^ 130 1.0 130 ~ 2, to \ t"~ T \a Compression 100 a1 a 100 Compression % 1.0 o 2. o 0 0 1. 21. 0 15' 0 ~ 1 151~_~, 0 10 10 1d 5 0 0 0 0 0 _ _ _ 0 ~ 0 1.0 2.0 0 1.0 2.0 Creep Deformation-% Creep Deformation-% Figure 20. - Effect of Prior Creep Exposure at 600~F on Tension and Compression Properties of Ti-16V-2. 5A1 at 600~F. WADC TR 59-454 59

10 hr Prior Creep at 8006F 100 hr Prior Creep at 8006F $~ 160 160 a* o0 0 150 150 140 140 ~ 8 o — -'-130 ~ -0- 130~ "-4 ^ 120 120 Code - -- Tension 110 C__ —— ompression O~ 10 ~ 110 P' Unexposed 100 10 I_ - 0 1,0 2. 0 3. 0 0 1.0 2.0 3.0 160 160 150 ~~~ 150 0i1 150 -~i t 50 0 140, 140 0 4 bo 130\ ~ 130 \ I<ub \ Compression U 120 Tension 120 a 03- - -0-~tt^^rT5 ^- -o- Tension ^^ ~ 110- Compression - 00 100 o00100 90~0 1.o 0 20 3090. 0. 0 3. O 1.0 2. 0 3.0 01T~ 5 ~ I I ___ __ 0 -_____ 5~____ _______________5 0 0 01.0 2. 0 3. 0 0 1,0 2,.0. 3,0 Creep Deformation - % Creep Deformation - % Figure 21, -Effect of Prior Creep Exposure at 800~F on Tension and Compression Properties of Ti-16V-2. 5A1 at 800~F. WADC TR 59-454 60

10hr Prior Creep at 900~F 100hr Prior Creep at 900~F 140..... 140 o 130 130 120 120 C" k Q0 w 110 110 0 ~{o 0. O10 7- I~ d 10O 1000 Code I, — ~ O --- Tension --- a — Compression 4 9g0 90 1.: f Unexposed 130 1 130,,120 120 0110 110. Compres.sion T nsin ^ ^^^ I 0"' -100 100 a /90 ^ Qo Tension 90 Compression 90 90 o 80 80 80f.'. i I 0o A 7 70 70 60 60 ________________________ a o _ O 2 O 3_,,,, 30o5 o 1 30 o g 20 20 -'~ I I I I o~~ 01o r g 10 10 0. ~~~ 0 Ou 1.70 2.0 3.0 0 1. 0 2.0 2,0 Creep Deformation-% Creep Deformation-% Figure 22, - Effect of Prior Creep Exposure at 900~F on Tension and Compression Properties of Ti-16V-2. 5A1 at 900F. WADC TR 59-454 61

a6 0 a! f ~i _ 30 L t....o l fJV I D^ ~ l^ l ] 900~F 5 0 0 10~ 230 ~~~~~~ 9 00 ~ O7000F Code 6000F 0 ______ _____ _ 05 600 "F o20 ~. 0 700"F Exposure rA 800~F Temperature t0O -i 0 9000F 0 Unexposed 0 10 20 30 40 50 60 70 80 90 100 30 ^ 700~6'~ Q 0 10 20 30 40 50 60 70 80 90 100 010 7 F09000F o 0 0 10 20 30 40 50 60 70 80 90 100 Exposure Time - Hours Figure 23. - Effect of Unstressed Exposure on Room Temperature Tension-Impact Properties of Ti-16V-2.5A1. WADC TR 59-454 62

40.................8.... _ 2 10 0 9000F) Test Temperature / Unexposed 50 4 0900 F 40 0o o 6- 0 600~ 10 0 10 20 30 40 50 60 70 80 90 100 10..'. - -' O 0 I bD - ~~ ~ 06000F Figure 24 Effect of Unstressed Exposure on Elevated TemperatureF Tension-Impact Properties of Ti-16V-2.5A1. 0WADC TR 59-454 0 30 40 50 6 0 70 80 90 100

0 0' lOhr Prior Creep at 600~F 10Ohr Prior Creep at 700~F 10Ohr Prior Creep at 800"F 10hr Prior Creep at 900~F - 60 ~ _60 __ 60 60 50 50 0 50 50 j o I 30 30 30 30 NN\ 0 0 lg 20 ~0 20 20~ 20 0 Creep Exposure o'~ f Unexposed 0c0 0 0 0 1 O0 I, 10 0 1.0 2. 0 0 1.0 2.0 0 10 2. 0 3.0 0 1.0 2.0 3.0.30. 30 301 0 30 0 0 20 00 0 __ 0 0 ~____ ___' IoI. 0 1.0 2,0 0 1.0 2.0 0 1.0 2.0 3.0 0 1.0 2.0 3.0 030 30 10 10 0o 0 o, 0 I 0 0 I 0 1.0 2.0 0 1.0 2.0 0 1.0 2. 0 3.0 0 1.0 2.0 3.0 Creep Deformation-lo Creep Deformation-% Creep Deformation-76 Creep Deformation-^ Figure 25. - Effect of Prior Creep Exposure on Room Temperature Tension-Impact Properties of Ti-_6V-2,5AI. Figure 25. - Efc fPirCepEpsr nRo eprtr eso-matPoete fT-6-.SL

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^Ff.:Qigur ~e 27(.1-.1000 F igure 28 ~~-~.; -:;.,:..-~"'- ~3;-."".' 5'.;~ ~'0 (ptcalMirorah)As-Treaed Eletr (Transverse~~~~~~~~~~~~~~~~~~^ Section) (Tases Section)..:-'. IA>~~~~~~~~~~f 7 Figure 27 xlOOO Figure 28 x3500 As-Treated (Optical Micrograph) As-Treated (Electron Micrograph) (Transverse Section) (Transverse Section) As -Treated (.Longitudinal Surface) As-Treated (Transverse Section) Ilk. ~ ~ ~ ~' RT Elong. 8.8^o RT Elong. 8.8%4. j'~:M l4^y^^^ -'~~ ~ ~ ~~~~~~~~ur -j v~~w~ 2" ^^'~ —^ "^^ - ~^y^W'^^^y ^'^A.- 2.: S. ~ y ^ ^.'-'" - ^-^-.J'. * is ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0 ^^-c^-^ri^ iisi-<-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii RT Elong. 2.0jo~~~~~~~~~~~~~~~~~~~* 4 2'~5 — 2 Im:'-:-<^ p' ~~? ^ *'.~^~.? ^. ^ <' ~.;. i' P'~ ^ * ^..-~;.'/:. ~.' ~'~ f!'!^: ~ ~'~~ t t,~c Fiur 312 x820 Figre r2tX 20 to ~k(..~ defrm tion (TaseseScin Note:~~52 RT Elong. is elonatio inroepeauetnsl fe Creep iTeted 100houspt- 60exSaeoasFgure3 Figures 27-32. - Electron Micrographs of Ti-16V-2,.5 Al Alloy, WADe TR 59-454 66

, -.'.r,NN I o 0 ~ ~ ~ ~ ~ ~ ~...~~~~~~~~~~~~ S'Nt/I ~ I. -~~~ctv -0-yi 2Zk.."MM_ / 4, ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - - ".,.,I ~~~~~~~~~I..I.~~~~~~~~~~~~~~~~~~~~.;... 0- ~ -'-'4 ---.- 2 A iN I -I N-4, NI'' I N C F 4 i ~ ~ ~ ".., - ~'~ N'" r.-. - -..,l "..,..... fI ~~~~~~~~~~~~~~~~~~~~~~~~~~~~1.," -I!,~~~~~.., ~~~. ~ ~, INN'...~- /N N Figure 37 x8200 Figure~V-;: 38 820 Creep*...:: Tested. 428,~ horsat900FSae s igre3 to 0 defrmaio (Tanvere ecton (Longiudina Sufae RT Elong. 5. 5%~ Note:RT Elng.,is elngatin inroom emperture ensil tes aftr ndiatd cee-exosre Figures 33-38, - Electron Micrographs of Ti-16V-2.5A1 Alloy WADC TR 59~~~~~-454 67

I

UNCLASSIFIED UNCLASSIFIED The University of Michigan Research The University of Michigan Research Institute, Ann Arbor, Michigan Institute, Ann Arbor, Michigan EFFECT OF PRIOR CREEP ON THE MECHANI- EFFECT OF PRIOR CREEP ON THE MECHANICAL PROPERTIES OF A HIGH-STRENGTH CAL PROPERTIES OF A HIGH-STRENGTH HEAT-TREATABLE TITANIUM ALLOY, Ti- HEAT-TREATABLE TITANIUM ALLOY, Ti16V-2.5A1, by J. V. Gluck and J. W. 16V-2.5A1, by J. V. Gluck and J. W. Freeman. March 1959. 67p. incl. Freeman. March 1959. 67p. incl. illus., tables, 6 refs. (Proj. 7360; illus., tables, 6 refs. (Proj. 7360; Task 73604). (WADC TR 59-454). Task 73604). (WADC TR 59-454). [Contract AF33(616)-3368]. [Contract AF33(616)-3368]. Unclassified report Unclassified report (over) UNCLASSIFIED (over) UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED The University of Michigan Research The University of Michigan Research Institute, Ann Arbor, Michigan Institute, Ann Arbor, Michigan EFFECT OF PRIOR CREEP ON THE MECHANI- EFFECT OF PRIOR CREEP ON THE MECHANICAL PROPERTIES OF A HIGH-STRENGTH CAL PROPERTIES OF A HIGH-STRENGTH HEAT-TREATABLE TITANIUM ALLOY, Ti- HEAT-TREATABLE TITANIUM ALLOY, Ti16V-2.5A1, by J. V. Gluck and J. W. 16V-2.5A1, by J. V. Gluck and J. W. Freeman. March 1959. 67p. incl. Freeman. March 1959. 67p. incl. illus., tables, 6 refs. (Proj. 7360; illus., tables, 6 refs. (Proj. 7360; Task 73604). (WADC TR 59-454). Task 73604). (WADC TR 59-454). [Contract AF33(616)-3368]. [Contract AF33(616)-3368]. Unclassified report Unclassified reporU (over) UNCLASSIFIED (over) UNCLASSIFIED

UNCLASSIFIED UNCLASSIFIED The effect of creep to 2 percent in 10 The effect of creep to 2 percent in 10 or 100 hours at temperatures from 600~ or 100 hours at temperatures from 600~ to 9000F was determined on the tension, to 900~F was determined on the tension, compression, and tension-impact proper- compression, and tension-impact properties of Ti-16V-2.5A1 at room temperature ties of Ti-16V-2.5A1 at room temperature or the exposure temperature. Prior creep or the exposure temperature. Prior creep at 600~F raised ultimate tensile and at 600~F raised ultimate tensile and yield strength. Lesser changes were yield strength. Lesser changes were found at higher temperatures. Changes found at higher temperatures. Changes in properties are attributed to a com- in properties are attributed to a combination of stress-accelerated age- bination of stress-accelerated agestrengthening and a Bauschinger effect. strengthening and a Bauschinger effect. UNCLASSIFIED UNCLASSIFIED UNCLASSIFUNC ULASSIFIED The effect of creep to 2 percent in 10 The effect of creep to 2 percent in 10 or 100 hours at temperatures from 600~ or 100 hours at temperatures from 600~ to 900~F was determined on the tension, to 900~F was determined on the tension, compression, and tension-impact proper- compression, and tension-impact properties of Ti-16V-2.5A1 at room temperature ties of Ti-16V-2.5A1 at room temperature or the exposure temperature. Prior creep or the exposure temperature. Prior creep at 6000F raised ultimate tensile and at 600~F raised ultimate tensile and yield strength. Lesser changes were yield strength. Lesser changes were found at higher temperatures. Changes found at higher temperatures. Changes in properties are attributed to a com- in properties are attributed to a combination of stress-accelerated age- bination of stress-accelerated agestrengthening and a Bauschinger effect. strengthening and a Bauschinger effect. UNCLASSIFIED UNCLASSIFIED

UNCLASSIFIED UNCLASSIFIED The effect of creep to 2 percent in 10 The effect of creep to 2 percent in 10 or 100 hours at temperatures from 600~ or 100 hours at temperatures from 600~ to 900~F was determined on the tension, to 900~F was determined on the tension, compression, and tension-impact proper- compression, and tension-impact properties of Ti-16V-2.5A1 at room temperature ties of Ti-16V-2.5A1 at room temperature or the exposure temperature. Prior creep or the exposure temperature. Prior creep at 600~F raised ultimate tensile and at 600~F raised ultimate tensile and yield strength. Lesser changes were yield strength. Lesser changes were found at higher temperatures. Changes found at higher temperatures. Changes in properties are attributed to a com- in properties are attributed to a combination of stress-accelerated age- bination of stress-accelerated agestrengthening and a Bauschinger effect. strengthening and a Bauschinger effect. UNCLASSIFIED UNCLASSIFIED LASSIED UNCLASSIFIED The effect of creep to 2 percent in 10 The effect of creep to 2 percent in 10 or 100 hours at temperatures from 600~ or 100 hours at temperatures from 600" to 900~F was determined on the tension, to 900~F was determined on the tension, compression, and tension-impact proper- compression, and tension-impact properties of Ti-16V-2.5A1 at room temperature ties of Ti-16V-2.5Al at room temperature or the exposure temperature. Prior creep or the exposure temperature. Prior creep at 600'F raised ultimate tensile and at 600~F raised ultimate tensile and yield strength. Lesser changes were yield strength. Lesser changes were found at higher temperatures. Changes found at higher temperatures. Changes in properties are attributed to a com- in properties are attributed to a combination of stress-accelerated age- bination of stress-accelerated agestrengthening and a Bauschinger effect. strengthening and a Bauschinger effect. UNCLASSIFIED UNCLASSIFIED

UNCLASSIFIED UNCLASSIFIED The University of Michigan Research The University of Michigan Research Institute, Ann Arbor, Michigan Institute, Ann Arbor, Michigan EFFECT OF PRIOR CREEP ON THE MECHANI- EFFECT OF PRIOR CREEP ON THE MECHANICAL PROPERTIES OF A HIGH-STRENGTH CAL PROPERTIES OF A HIGH-STRENGTH HEAT-TREATABLE TITANIUM ALLOY, Ti- HEAT-TREATABLE TITANIUM ALLOY, Ti16V-2.5A1, by J. V. Gluck and J. W. 16V-2.5A1, by J. V. Gluck and J. W. Freeman. March 1959. 67p. incl. Freeman. March 1959. 67p. incl. illus., tables, 6 refs. (Proj. 7360; illus., tables, 6 refs. (Proj. 7360; Task 73604). (WADC TR 59-454). Task 73604). (WADC TR 59-454). [Contract AF33(616)-3368]. [Contract AF33(616)-3368]. Unclassified report Unclassified report (over) UNCLASSIFIED (over) UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED The University of Michigan Research The University of Michigan Research Institute, Ann Arbor, Michigan Institute, Ann Arbor, Michigan EFFECT OF PRIOR CREEP ON THE MECHANI- EFFECT OF PRIOR CREEP ON THE MECHANICAL PROPERTIES OF A HIGH-STRENGTH CAL PROPERTIES OF A HIGH-STRENGTH HEAT-TREATABLE TITANIUM ALLOY, Ti- HEAT-TREATABLE TITANIUM ALLOY, Ti16V-2.5A1, by J. V. Gluck and J. W. 16V-2.5A1, by J. V. Gluck and J. W. Freeman. March 1959. 67p. incl. Freeman. March 1959. 67p. incl. illus., tables, 6 refs. (Proj. 7360; illus., tables, 6 refs. (Proj. 7360; Task 73604). (WADC TR 59-454). Task 73604). (WADC TR 59-454). [Contract AF33(616)-3368]. [Contract AF33(616)-3368]. Unclassified report Unclassified report (over) UNCLASSIFIED (over) UNCLASSIFIED