THE UNIVERSITY OF MICHIGAN RESEARCH INSTITUTE ANN ARBOR, MICH. NINTH PROGRESS REPORT TO MATERIALS LABORATORY WRIGHT AIR DEVELOPMENT CENTER ON EFFECT OF PRIOR CREEP ON MECHANICAL PROPERTIES OF AIRCRAFT STRUCTURAL METALS by J. V. Gluck H. R. Voorhees J. W, Freeman Project 2498 Air Force Contract No. AF 33(616)-3368 Supplement Nos. 3(58-1715) S5(58-2202) Task No. 73605 July 15, 1958

SUMMARY This report covers progress under Contract AF 33(616)-3368 for the period from April 1, 1958 to June 30, 1958 on a study of the effect of prior creep on the short-time mechanical properties of aircraft structural sheet metals, The materials under investigation include 17-7PH precipitation hardening stainless steel in the RH 950 condition and two titanium alloys, Cl1OM and MSM 16V-2,5A1, During this reporting period, a Sumnzary Report covering studies of C1 10M through the end of 1957 was reproduced and distributed, Experimental work included the continuation of studies on the 17-7PH alloy (RH 950 condition),, Base properties in compression were determined at room temperature, 600%, 800~ and 900PF and unstressed exposures were conducted at the elevated temperatures for periodsof 10, 50, or 100 hours, Subsequent tensile and compression tests at room temperature and the elevated temperatures revealed increased tension and compression strength and decreased ductility- -particularly for the higher e:xposure termperatures and times, Tests of 17-7PH after stressed exposure showed that severe losses in room temperature tensile ductility followed prior creep for 100 hours at 600 F,, Specimens similarly exposed at 800~F showed a loss of ductility that was more a function of temperature rather than the amount of prior creep, Orientation studies of C 1OM revealed appreciable differences in mechanical properties depending on the orientation of the specimen to the sheet rolling direction, Bauschinger effects following creep exposure were found at all specimen orientations studied,

Additional work included phase identification studies on 17-7PH (RH 950), continuation of development of tension-impact stress-strain recording equipment, and initiation of deformation path studies of CL1OM,

INTRODUCTION This report, covering the period from April 1 to June 309 19589 is the ninth progress report to be issued under Air Force Contract No,, AF33(616)-3368, Research now in progress is being carried out under Supplemental Agreements Nos, 3(58-1715) and S5(58-2202), The purpose of the investigation is to study the effects of prior elevated temperature creep-exposure on the mechanical properties of aircraft structural sheet alloys, Materials previously evaluated included 2024-T86 aluminum (Ref, 1)9 17-7PH stainless steel in the TH 1050 condition (Ref, 2) and C110M titanium alloy (Ref, 3), Presently, background studies are being conducted on 17-7PH stainless steel in the RH 950 condition and are scheduled to be conducted on MSM 16V-2, 5A1 titanium alloy,, In addition9 the results of the previous evaluation of C11 OM have led to the initiation of special studies on specimen orientation and Bauschinger effects and a study of the relative influence of short-time strain or creep strain on subsequent mechanical properties, Basic evaluations of all test materials consist of exposure either stressed or unstressed for periods up to 100 hours at temperatures low, intermediate or high in the creep range, Following the exposures, the tensile, compression9 and tension-impact properties are determined both at room temperature and the exposure temperature, The primary exposures are for 109 509 or 100 hours at either zero stress or to stresses selected to yield 0, 29 0~ 5, 1 0, or 2, 0 percent creep deformation, Exposure temperatures of 60099 800~, or 900'F are presently being utilized for studies of 17-7PH (RH 950 condition), The mechanical properties of the exposed material are then compared with those of the unexposed material as established by a number of tests of

2 specimens chosen at random, In all cases, correlations are based on the actual deformation reached during the creep-exposure since the stress employed can only be the average value determined to give the required deformation in the specified time interval, Loading data taken for each test permit the calculation of total deformation and short-time plastic strain, if any, The test materials are obtained in the form of 0 064-inch thick sheet stock, with the specimens cut from the sheets in the nominally weaker direction, Thus, the stainless steel is tested transverse to the rolling direction, while the titanium alloys are tested in the longitudinal direction, The titanium alloy, MSM 16V-2, 5A1, is furnished by the manufacturer in the solution treated and aged condition, while the 17-7PH stainless steel is heat treated to the RH 950 condition at the University,, This process includes solution treatment, refrigeration, and aging, For ease in planning, accomplishment, and reporting, the research program has been arranged so that it can provide information on a seri.es of topics or sub-projects, The following list indicates the nature of the topics under consideration, 1, Relation of Heat Treatment to Alteration by Prior Creep of Mechanical Properties of a Heat-Treatable Stainless Steel (A study of 17-7PH in two heat treatments (TH 1050 and RH 950), 2, Metallurgical Characteristics of Titanium Sheet Alloys Governing Alteration of Mechanical Properties by Prior Creel; (A study of MSM, 16V-2, 5Al with comparison to C 1OM), 3, Anomalous Effects of Prior Creep on Comn;preissive and Tensile StressStrain Characteristics of Aircraft Structural Srheet Alloys (An inve tigation of Baus chin er effect J and s pecimen orientation),

3 4, Evaluation of the Influence of Prior Creep on the Tensile and Cold-Bend Test Ductility of Aircraft Structural Metals, 5, Tension-Impact Stress-Strain Characteristics of Aircraft Structural Metals After Exposure to Prior Creep, 6, Metallurgical Factors Controlling the Influence of Prior Creep on Mechanical Properties of Aircraft Structural Metals, 7, The Role of Creep Recovery in Aircraft Structural Metals Exposed to Creep, 8, The Relative Importance of Short-Time Strain and Creep Strain on the Alteration of Mechanical Properties of Aircraft Structural Sheet Metals, TEST MATERIALS AND SPECIMEN PREPARATION Specimen blanks are sampled at random from the various sheets of test stock, Consistent with the dimensions of the sheets, a repeating sampling and numbering scheme permits identification to be made of the original location of any test specimen, The details of the numbering schemes and specimen dimensions were previously given (Refs, 2 and 3), All specimens for exposure are machined slightly oversize in the gage section, The excess stock is then removed prior to mechanical testing in order that edge effects, if any, associated with the exposure could be eliminated. The analysis and heat treatment details for the 17-7PH stainless steel in the RH 950 condition were given previously (Ref. 4), Late in this report period word was received of the shipment of the MSM 16V-2, 5A1 titanium alloy, The pertinent information for this material is given below,

4 MSM 16V-2, 5A1 Word was received from the Mallory-Sharon Metals Corporation on June 26, 1958 of the shipment of 3 sheets 0, 063 x 36 x 92-105 inches of MSM 16V-2, 5A1 titanium alloy, This material was allocated to the present investigation through the Department of Defense Titanium Sheet Rolling Program, The shipment consists of Sheets 0084-1, -2, and -7 from Heat No, M-22154, The reported heat treatment consisted of a 1/2-hour solution treatment at 1380'F, water quenching, aging for 4 hours at 990~F, and air cooling, The following chemical analysis was furnished: Element Wt, Percent C 0,02 N2 0,014 H2 0, 0076 - 0. 0078 (76-78 ppm) Fe 0,27 Al 2, 56 V 15, 79 EQUIPMENT AND PROCEDURES Wherever applicable, ASTM Recommended Procedures are adhered to in test procedures, Other testing details follow practices developed at the University of Michigan,, Equipment and procedures were previously discussed in References 1, 2, and 3, RESULTS AND DISCUSSION Experimental work accomplished during thion reporting period included: the determination of the base condition compression properties of 17-7PH (RH 950 condition); the determination of the effects of unstressed exposure on

tension and compression properties of this material; and partial completion of stressed exposure tests for several conditions of time and temperature, Further work included: A study of the effect of specimen orientation on mechanical properties and Bauschinger effects in C lO1M titanium; continuation of development of equipment for stress strain recording in tensionimpact testing; and attempts to identify phases in 17-7PH (RH 950) by X-ray techniques, A study of the effects of various paths to reach a final deformation was initiated on C 110M, Finally, a summary report covering studies of ClIOM to December 31, 1957 was approved and preliminary copies were reproduced and distributed, Project 1o Relation of Heat Treatment to Alteration by Prior Creep of Mechanical Properties of a Heat-Treatable Stainless Steel Compression Properties of 17-7PH (RH 950 Condition), Compression tests were carried out at room temperature, 600~, 800~, and 900~F to establish the average properties of 17-7PH stainless steel as-heat treated to the RH 950 condition. The data are tabulated in Table 1 and plotted as a function of test temperature in Figure 1. Increasing the test temperature caused the compression yield strength to decrease, with the temperature dependence quite similar to that previously reported for the tensile properties (Ref, 4), The compression yield strength ranged from 10-15 percent higher than the tensile yield strength and was generally equal to the ultimate tensile strength. In this respect the behavior of the RH 950 condition was different from that of the TH 1050 condition, since in the latter, the room temperature and 6000F compression yield strengths were about 10 percent higher than the ultimate tensile strength,

6 The compression yield strengths developed in this lot of material (Heat No,, 55651) at room temperature and 600 F were about 10 percent higher than those indicated by the producer as "'typical" (Ref, 5)t This was a slightly higher deviation than was found previously in the case of the tensile properties (Ref, 4), Tensile Properties After Unstressed Exposure of 17-7PH (RH 950 Condition),, Tensile tests at room temperature or the exposure temperature were conducted on samples of 17=7PH (RH 950) following exposure without stress for 109 509 or 100 hours at temperatures of 600~, 800~, and 9006F, The test data are summarized in Table 2. Room-temperature results are plotted in Figure 2 and the elevated-temperature results are plotted in Figure 3, The room temperature results (Fig,, 2) show that no change in strength followed exposure at 600@F, Both the ultimate tensile and yield strengths were increased by exposure at 800~ or 900~F with the maximum effect possibly occurring after 100 hours at 800~F, For this condition the tensile and yield strengths were increased about 12 13 percent over the base value,, Accompanying the increased strength was a substantial decrease in ductility which was most marked for the 900@F exposures, The accompanying hardness changes (Fig, 2) were neither large nor appeared to be consistent, Tests at elevated temperature (Fig, 3) revealed possible increases in tensile and yield strength after exposures at 600~ and 900~F and a definite effect from 100 hours at 800'F=-the condition of maximum effect in the room temperature tests, In this instance, the tensile strength was increased about 10 percent and the yield strength about 15 percent over the base value, The 600@ and 900~F yield strengths were increased somewhat following exposure, however, the 600~F ultimate tensile strengths were not affected,,

7 The 900'F ultimate tensile strength reached a maximum at 50 hours exposure and then decreased after 100 hours exposure, Ductility tended to decrease with increasing exposure time with the possible exception of the 600~F tests, Compression Properties After Unstressed Exposure of 1 7-7PH (RH (H950 ConditCion). Compression tests at room temperature or the temperature of exposure were run on specimens of 17-7PH (RH 950 Condition) given unstressed exposure at 600", 8000, or 900F for 10, 50, or 100 hours. The results of these tests are presented in Table 3 and plotted in Figures 4 and 5, The suggested increase in strength at room temperature (Fig, 4) following exposure at 6000F was probably not significant since the test values fell within the range for unexposed material, Larger and probably significant increases followed exposures at 800~ or 900F,r The maximum increase in strength (for the 50 and 100 hours exposure at 8000 or 900~F) was about 9 percent above the average value for the base conditions This was somewhat above the range of values obtained in tests of the as-treated material (Fig, 1) and is, therefore, probably a real effect, A check test on a second specimen exposed for 50 hours at 800'F showed excellent agreement with the first test of this condition, The elevated temperature test results (Fig, 5) exhibited some increase in strength with increased exposure time. The maximum increases, those for the 100 hours exposure at each temperature, ranged from 6-12 percent above the average base value, Check tests were run on several exposure conditions,

8 Properties After Creep-Exposure of 1.77PH (RH 950 Condition) Available results of room temperature tensile and compression tests of 17-7PH (RH 950 condition) following creep-exposure are summarized in Tables 4 (tensile data) and 5(compression data), Combined plots of the tensile and compression results at room temperature and elevated temperature are presented in Figures 6 and 7, The inclusion of both the tension and compression yield strengths on the same plot helps emphasize the possible existence of Bauschinger effects, The conditions for which enough tests have been completed to warrant presentation include 100 hours prio creep at 600~ and 800'F and 10 hours at 900F,, The 100-hour exposure to creep at 600OF had a marked effect on the strength and ductility at room temperature (Fig, 6), while the properties following the 800 F exposure appeared to be more a function of the exposure to temperature alone, The 900~F results showed a large temperature effect and a possible fall-off in properties with increased creep, The room temperature results indicate that small amounts of prior creep at 600'F vwere very potent in increasing the ultimate tensile and tensile yield strengths and decreasing the compression yield strength, The ratio between the yield strengthswas also changed drastically, It should be recognized, however, that some plastic strain-up to 25 percent of the total plastic strain obtained in the exposure —occurred during loading, The behavior of the yield strengths following creep at 600 F was similar to that observed for the TH 1050 condition of this material at 600%F and C1OM titanium at 6507 and 700'F (Ref, 2 and 3), In the ClIOM alloy this was identified as Bauschinger-type behavior, In addition to effects on strength9 the elongation of the tensile test samples was sharply reduced from the as

9 treated value; appearing to level off at about 1 percent for creep of about 0, 5- 1 0 percent, Thus, in another respect: the behavior of the RH 950 condition after creep at 600'F was qulite similar to that of the TH 1050 condition,, Specimens pre-crept at 800',F were little changed in strength from those exposed to 800'F in the absence of stress, Elongation values for samples crept at 800 F were low, but not much lower than those of samples giveln exposure to temperature alone, The presence of Basuchinger effects following prior creep at 800tF is questionable, Prior creep for 10 hours at 900'F was followed by a decrease in the ultimate and tensile and compression yield strengths at room temperature, Elongation values were relatively unaffected although a minimum may exist for samples subjected to intermediate amounts of creep deformation, Contrary to the experience from tests at 600FF, the total plastic strain obtained at 800 and 900 F was entirely due to creep deformation in all. but two tests, Even in these two instances, the plastic loading deformation was almost negligible, The results of mechanical property tests at the exposure temperature on samples subjected to prior creep are plotted in Figure 7, As Tables 4 and 5 indicate9 the test data are as yet sparse and the plots should be regarded merely as indications of possible trends,, Prior creep for 100 hours at 600'F appears to increase the ultimate and tensile yield strengths while decreasing the compression yield strength and tensile elongation, A substantial Bauschinger effect appears to be present in the 600'F data, The effects of prior creep at 800~ and 900%~F on the mechanical properties at these temperatures do not appear to be large (Fig,, 7), Some decrease was

10 observed in the ultimate strength, and there are indications of a reversal in the tension and compression yield strengths, The elongation values for these tests were inconsistent, Further testing will include both check tests and the extension of exposure conditions to the full range of times9 temperatures9 and deformations indicated in the introduction, When this is complete, appropriate comparisons will be made with the data for the TH 1050 condition, Project 3o Anomalous Effects of Prior Creep on Compressive and Tensile Stress-Strain Characteristics of Aircraft Structural Sheet Alloys Specimen Orientation and Bauschinger Effects In the initial studies of the C 10M titanium alloy (Ref. 3) an apparent anomaly was discovered between the relative magnitudes of the tension and compression yield strengths of as-received specimens taken in the rolling direction, This was the fact that, instead of being almost equal to the tension yield strength —so-called "normal" behavior-the compression yield strength was about 25 percent lower, The original test results — nine tests each in tension and compression-were rechecked by an additional five compression tests at room temperature and three tests at 700 F,, In two instances, the specimen support force was drastically increased with no significant change in the previously determined compression yield strength (Ref, 3), In addition, C10OM stock was exchanged with the Republic Aviation Corporation and the University and Republic each ran tests on the other's material, Good agreement was obtained between test results (Ref, 6), This confirmed first that the test procedures used at both organizations were valid and secondly, that the anomaly in the yield strengths of the University's test stock was indeed a real one, Further investigation revealed the existence

11 of Bauschinger effects, probably resulting fromn the presence of residual tensSil stress in the rollin.g direction of the as produced materiale Limited tests of specimens taken transve rse to rolling revealed almost the opposite situation, It was further noted that exposure to temperature alones particularly at 700@ or 800F9, could eliminate the disparity between the two yield strengths, The evaluation of mechanical, properties of this alloy following creep was confined to longitudinalr specimens, These studies showed that exposure to creep in tension resulted in an increase in the tensile yield strength and a decrease in the compression yield strength, For example9 after prior creep to 1 percent in 10 hours at 700~F, the room-temperature tensile yield strength was some 50 percent higher than the compression yield strength,, Inasmuch as these studies were carried out on longitudinal specimens9 a question renmained concerning the generality of the results,, Consequently9 a study was undertaken of the effect of speci.men orientation on mechanical properties and the behavior following creep, The results to date of this investigation are summarized in Table 6 and plotted in Figures 8 and 9D Specimen blanks were cut fromw the sheet at 300, 45 ~ 60~ and 90~ to the rolling direction Creep exposures were conducted at 700~F for 10 hours at stresses expected to yield cr eep deformations up to 2 percent,, Figure 8 is a plot of the effect of specimen orientation on the shorttim e mechanical properties of C l10M at room temperature, The values for the orientation of O~ to rolling are the avera.ges of the nine tension tests and fourteen compression tests previously referred to, This figure shows that a very definite increase in compression yield strength occurred as the spec imen orientation deviated from the rolling direction, Of course, this results in a

12 changing relationship between the tension and compression yield strengths, Only at 30' to the rolling direction were the tension and compression yield strengths equal, At orientations of 60~ and 90~ to rolling, the compression yield strength was about 1,5-20 percent higher than the tensile yield strength,, The maximum ductility appears to fall between 30' and 45~ to the rolling direction, while the minimum occurs at 60~, Modulus values were calculated from the slopes of the stress-strain curves and, therefore, should not be regarded as precise, Figure 9 summarizes the effect of prior creep for 10 hours at 700~F on the subsequent room-temperature properties, In general, increased creep in the tension direction of this material —regardless of the orientation of the specimen —had the following effects on mechanical propertieso The ultimate tensile and tensile yield strengths were increased; the tensile yield strength became equal to the ultimate strength; the compression yield strength was decreased; and except at 60~, the ductility was decreased, Hardness changes (Table 6) were small and inconsistent0 The increase of tensile yield strength and decrease of compression yield strength with increased plastic deformation are manifestations of Bauschinger effects,, Even in those cases where compression yield strength was originally higher than tensile yield strength, i, e,, for orientations above 30~, the increase in strength was dissipated; partially by exposure to temperature alone, and then by deformation, The fact that the tensile yield strength became equal to the ultimate tensile strength indicates that the shape of the stress-strain curve had changed to include the sharp "knee" associated with the Bauschinger effect,

13 Although the plots in Figure 9 are based on creep deformation, it should be realized that an appreciable plastic deformation occurred during the loading of a number of the tests. Examination of Table 6 shows that this was especially true for specimens oriented at 30" and 45~ to the rolling direction,, In fact, the plastic deformation of these specimens was so rapid and so large during loading that in some cases, the final deformation could only be estimated from the full scale travel of the extensometer system, Thus, the actual deformation might be even higher than the estimate, The behavior of CIOM in first stage creep appears to be subject to considerable directionality, Tentatively, it can be concluded that the effects of prior creep on mechanical properties of C I I OM are fairly general for all orientations even though the initial properties may vary,, Project 5o Tension-Impact Characteristics of Aircraft Structural Sheet Alloys After Prior Exposure to Creep Development of Equipment Work has continued on the development of equipment and instrumentation for the recording of stress-strain data in tension-impact testing. The basic system was described previously (Ref, 4). Present experiments are concerned with the use of 34-.gage nichrome wire for a strain gage, A set of miniature collars was constructed to clamp directly on the impact specimen gage section. The nichrome wire looped between these collars forms one side of a two-gage bridge with the compensating gage consisting of a similar length of nichrome taped to the impact specimen holder. The gages are connected to an Ellis BA-2 Bridge and Amplifier Unit which is in turn connected to a dual-channel oscilloscope, The other channel

14 of the oscilloscope is connected to a similar amplifier which receives the output of a four-arm SR -4 strain gage bridge mounted on a tension link in the impact strain, Using this arrangement, several photographic recordings have been made of stress and strain versus time during impact fracture, Experimentation has been directed towards selection of the proper triggering point, amplitude, and sweep speed in order to record the largest possible trace on the face of the oscilloscope, Further work is required on the initial balancing of the strain measuring circuit, When this is complete, the unit will be calibrated, Project 6: Metallurgical Factors Controlling the Influence of Prior Creep on Mechanical Properties of Aircraft Structural Metals Metallographic and X-Ray Examination of 17-7PH (RH 950 Condition), Specimens of 17-7PH (RH 950 condition.) were examined both in the as-treated condition and after creep at 800~F in an attempt to relate changes in mechanical properties to metallurgical factors. The techniques employed were those of light microscopy and X-ray diffraction analysis, The microstructure produced by the RH 950 treatment has been described as consisting of tempered martensite, chromium compounds, and aluminum compounds (presumably aluminum nickel) (Ref, 5). Figure 10 shows the material in the as-treated condition, The stringers observed in Figure 10 have the appearance of delta ferrite but a positive identification has not been made, Figure 11 is a micrograph of a specimen subjected to 100 hours creep at 800~F and 115, 000 psi, Total plastic deformation was 0, 94 percent —all of which occurred during creep, Visible microstructural differences between the two samples were slight and probably as much due to a difference in the response to etching as to the over-aging of the background constituent,

15 Table 7 summarizes the mechanical properties of the samples and the results of X-ray diffraction examination, As the table shows9 an increase in the ultimate tensile and tensile yield strengths and a severe loss of ductility occurred after creep at 8009F, Hardness was also increased, An asymmetric Phragmen-type camera was used to obtain x-ray diffraction patterns from the solid samples, Exposure was for 10 hours using unfiltered chromium radiation, Since this particular camera was not calibrated, filings were made of the as-treated sample (specimen G-1) and a Hull-Debye-Scherrer pattern was made in a 1 14, 6 mm diameter camera,, An exposure of 6 hours was used with vanadium-filtered chromium radiation, The diffraction patterns from the filings were identified (Table 7, Part A) as martensite (matrix) with an average lattice parameter of 2, 88A ( No other lines were observed, These lines were then used to index the patterns obtained in the Phragmentype camera (Table 7, Part B), Analysis of these films was somewhat complicated by the presence of the P reflections, The diffraction patterns from both solid samples were found to consist of matrix lines (martensite) and several other weak lines which could not be completely identified, Factors which precluded the identification include the followingo 1, Several phases may exist for which only the stronger lines are recorded on the film,, This would tend to make identification very difficult since many of the carbide-type precipitates have their stronger lines at the same or very similar "d's values, 2, Some of the lines which might be used to differentiate between various carbides could be superimposed on the matrix lines,

16 3, Many diffraction lines that might conceivably be useful fall at "d" values of less than 1, 17, These are not recorded by the camera used-the only one presently available for exposures on solid samples, 4, The actual lines might be from compounds not yet identified, Thus, there might not even be standard patterns in existence for comparison purposes, A possible case could be made for identification of the unknown lines as coming from CrC0 This would be based on the 2, 07, 1, 80, and 1, 29 "d"-value lines, However, the remaining lines cannot be accounted for, As far as could be determined, the patterns from the two samples were identical, Therefore, if further precipitation occurred during the creep exposures, it was probably the same compound or compounds that were produced in the original RH 950 treatment, since, if a reasonable amount of new phase did precipitate, it should be evidenced in the pattern for specimen G-2g Due to the weakness of the diffraction lines it was not possible to determine if a change in the intensity occurred as a result of the creep exposure, If this could be established, then a determination could be made of the occurrence of further precipitation of the original compound or compounds, Further study is being given to the use of more refined techniques for the analysis of these sepcimens, These procedures would include phase separation in solutions such as bromine-methyl alcohol and/or electrolytic hydrochloric acid, X-ray diffraction patterns would then be run on the residues, The above technique has a serious drawback in that extremely fine residues might be lost, This difficulty might be surmounted by the use of extraction replicas and selected area electron diffraction —or possibly chemical or fluorescent analysis of the residues, It should be realized, however9 that the above techniques are not only difficult and time-consuming9

17 but the possibility of obtaining definitive results is not assured, Therefore, the extension of effort too far along these lines will be the subject of careful consideration, Project 8: The Relative Importance of Short-Time Strain and Creep-Strain on the Alteration of Mechanical Properties of Aircraft Structural Metals In studies previously conducted on the 17-7PH alloy (TH 1050 condition) (Ref, 2) and CllOM (Ref, 3), prior creep-exposure was found to have an appreciable effect on mechanical'properties, Analyses of the creep=exposures revealed that, in many cases, the total deformation consisted not only of that occurring in the creep process, but also short-time plastic strain during loading, Consequently the relative influence of the two sources of plastic strain was not immediately apparent, During the present report period, additional work was authorized under Supplement S5(58-2202) to the basic contract for so-called "deformation-path" studies. Such studies involve the production of a given amount of final plastic strain, the strain to be achieved by following a number of different paths, Examples of the paths includeo 1, Pre-strain; unload, then time at temperature 2, Time at temperature; then post strain 3, Creep only (no plastic loading deformation) 4. Plastic loading deformation plus creep 5, Cyclic loading (combinations of paths 1 4 with no-load periods of exposure 9 etc, These studies are to be carried out on the C IOM titanium alloy and will be integrated, if possible, with the Bauschinger effect studies of Project 3, In order to cover as wide a range of creep deformation as possible, a basic

18 exposure of 100 hours at 700'F has been selected, Specimens are to be exposed under these conditions to reach total plastic strains of approximately 0O 5 and 1, 5 percent, Following this, short-time tensile and compression tests are to be conducted at room temperature, Specimens have been exposed to date under Paths 1F 29 and 39 although mechanical property tests have not yet been conducted, Fairly good success has been achieved in producing the required deformations in the "post-strain" and "creep-only" paths, Extension of the exposures to cyclic paths will be undertaken shortly,,

19 FUTURE WORK Work planned for the near future includes the followingo Project 1 a, Continuation of creep-exposure tests of 17-7PH (RH 950), Project 2 a, Determination of base properties of MSM 16V-2, 5Ale b, Establishment of curves of stress-versus time for creep deformation of MSM 16V-2, 5A1 for selection of creepexposure conditions, Project 3 a, Conclusion of orientation studies of Cl10M, Project 5 aM Completion of development of tension-impact stress strain recording equipment, Project 6 a, Phase identification studies of 17-7PH (RH 950), b, Familiarization with microstructure of MSM 16V22, 5A1, Project 8 a. Mechanical property tests of "path study" specimens, b, Extension of paths to cyclic loading,

20 REFERENCES 1, Gluck, J, V, Voorhees, H, R,, and Freeman, J, W., "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals," 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," WADC Technical Report 57-150 Part II, November 1957, 3, Gluck, J, V,, Voorhees, H, R,, and Freeman, J. W,, "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals," WADC Technical Report 57-150 Part III, January 1958, 4M Gluck, J, V,, Voorhees, H, R, and Freeman, J, W, "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals," WADC Progress Report 8 on Contract AF 33(616)-3368, April 15, 1958, 50 Marshall, M, W, Perry, De C, and Harpster, N, R, "Enhanced Properties in 17-7 Stainless" Metal Progress, V, 70, No, 1, p. 94-98 (July 1956), 6, Private Communication from Republic Aviation Corporation, Farmingdale, New York, dated May 6, 1958,

TABLE I COMPRESSION TEST DATA FOR AS-HEAT TREATED 17-7PH ALLOY (RH 950 CONDITION) 0. 2%5 Offs e t Compression Test Temp. Yield Strength Modulus, E ('F) Spec. No. (psi) (10 psi) Roomn 4B-T25 236,000 30. 2 4K-T46 2 54,000 31 2 24.5,000 30.7 5J[-'1 6 2 34,000 3 1. i 5E-3X 252,000 31, 2.13,000 31.1 J.-X2 z23, 000 30. 3 6E:-X2 2,8, 000 29. 9 24.0,000 0. 1 8ST47 259,000 30, 0 Average - 7 teast 245, 00 30. 6 600 4IB-T27 222,000 29, 8 4K-T42 194,500 29.0 207,250 29.4 5R-T27 200,000 28.8 5J-T24 186,000 28 5 1 93,000 28.6 6GX2 199,500 27.0 6AX2 201,000 28. 8 200,250 27.9 8S-T41 191,000 27.3 Average - 7 tests 199, 142 28.4, 800, 4K-T47 176,000 26.4 4B-T23 163,500 25. 6 169,250 26.0 5J-T23 167,000 26.6 5R-T23 175,000 26. 6 171,000 26. 6 6L-T51 170, 000 25.8 6L-T54 152,000 25.9 161,000 25,8 8S-T45 168,000 23.3 Average - 7 tests 167,357 25. 7 900 4K-T44 138,000 23,8 4B-T21 120,000 22. 6 129,000 23.2 5R-T'22 141,000 23, 1 5R-T25 137,000 23, 1 1 39,000 23, 6L-T56 136,000 2 5. 6L-T53 137,000 23.6 136,500 2.4, 5 Average - 6 te;)t. 1734,833 23,6

TABLE 2 EFFECT OF UNSTRESSED EXPOSURE ON TENSILE PROPERTIES OF 17-7PH (RH 950 CONDITION) Tensile Properties After Exposure Exposure Conditions Ult. Tensile 0.2% Offset Temp. Stress Time Test Temp. Strength Yield Strength Elongation Reduction of Modulus, E Hardness Spec. No. ('F) (psi) (hr) ('F) (psi) (psi) (%/2 inches) Area (%) (106 psi) (R"C"*) 4E-T2 600 none 10 room 241,000 226, 000O 7.0 14.5 30.0 48. 9 6F-T5 600 none 50 room 242,000 224,000 7.5 16.5 29.8 -- 5M-T6 600 none 100 room 238,000 226,000 7.0 10.4 28.5 49.0 5R-Ti 800 none 10 room 244,000 233,000 5.0 16.4 29.2 49.0 4H-T2 800 none 50 room 253,500 236,000 5.5 12. 1 28.3 49.0 7A-T5 800 none 100 room 267,000 250,500 3.5 4 7 29,5 51.0 6T-T6 900 none 10 room 258,000 242,000 2.8 6.7 31.5 47 9 5T-T6 900 none 50 room 252,000 240,000 2 5 4.3 28.3 49.5 5J-T6 900 none 100 room 254,000 246,000 2. 8 8. 5 29.4 46. 5 5C-T6 600 none 10 600 198,000 183,000 6.0 15.7 25.2 49.4 4K-T6 600 none 50 600 202,500 171,000 6.5 16.6 27.2 50.0 6D-T6 600 none 100 600 203,000 184,500 7.0 i4.2 29.5 45.0 4N-T5 800 none 10 800 174,000 157,000 11.5 23.6 22.9 51.4 5T-T1 800 none 50 800 169,000: 155;700 14.5 28.0 23.9 49.0 5Q-T2 800 none 100 800 185,000 169,000 8.5 2 1.0 25.2 50.8 4P-T1 900 none 10 900 142,000 130,400 18. 5 36.8 20.5 5i. 1 6H-T6 900 none 50 900 151,500 136,000 14.0 38.8 21.9 51.0 4K-T 900 none 100 900 132,000 T27,000 14.0 35.2 2 0.3 50.0

TABLE 3 EFFECT OF UNSTRESSED EXPOSURE ON COMPRESSION PROPERTIES OF 17-7PH (RH 950 CONDITION) Compression Properties After Exposure Exposure Conditions 0. 02 —2 Offset Compression Temp. Stress Time Test Temp. Yield Strength Modlus, E Spec. No. (*F) (psi) (hr) ('F) (psi) (10 psi) 4K-T45 600 none 10 room 237,000 28.9 5E3X2 600 none 50 room 244,000 29.7 6L-T52 600 none 100 room 248,000 30 7 5R -T24 800 none 10 room 256,000 30. 7 4K-43 800 none 50 room 262,000 29.8 8S-T46 800 none 50 room 260,500 30. 8 261,250 30 3 4K-T41 800 none 100 room 261,000 30 2 4B-T22 900 none 10 room 263,000 30. 3 5J-T22 900 none 50 room 267,000 30 8 5J-T25 900 none 100 room 266,000 30, 0 5R -T26 600 none 10 600 173,000 30.0 4N-T31 600 none 10 600 202', 000 28.7 187, 50O 29.3 6MX2 600 none 50 600 201000 28, 9 4B-T26 600 none 100 600 214,000 29 3 6L-T57 800 none 10 800 157,000 28. 3 5J-T21 800 none 50 800 180,000 27 8 6RX2 800 none 100 800 189,500 27.9 4N-T32 800 none 100 800 182,000 26, 5 185,750 27.2 5R-T21 900 none 10 900 138,000 23.6 4B-T24 900 none 50 900 130,500 23.9 8S-T42 900 none 50 900 153,000 25. Z 141,750 24,6 6L-T55 900 none 100 900 147,000 25.0

TABLE 4 EFFECT OF PRiOR CREEP-EXPOSURE ON TENSILE PROPERTIES OF 17-7PH (RH 950 CONDITION) Actual Exposure Conditions Tensile Properties After Exposure Nominal Exposure Condctions Total Plastic Total Test Ult. Tensile 0. 29% Offset Reduction Temp. Time Creep Def. Time Temp. Stress Load. Del. Load. Def. Creep Def. Plastic Temp. Strength Yield Strength Elongation of Area Modlus,EHardness ({F) (hrs) () Spec. No. (hrs) ('F) (psi) (%) (%) () Def. (%) (F) (psi) (psi) (%/2 inches) (9) (10 psi) (PC') 600i 100 0.2 5R-T3 100.0 600 152,000 0.60 0.06 0.17 0.23' room 247,000 239,000 7.5 15.6 291 49 600 100 0, 5 4EK-T2 100.0 600 179,000 0.84 0. 16 0.68 0.84 room 258,000 254, 000 1.5 9.0 28.6 48 600 100:.. L-Ti 100.0 600 177,000 0.90 0.30 1,12 1.20 room 261,000 261,000 1.0 -- 28.5 50 600 i00 2.0 4P-T4 100.0 600 181,200 1.0 0.34 1.64 1.98 room 263,000 263,000 1.0 7.4 30.50 800 100 0,2 5R-T5 100.0 800,- 82,000 0.32 nil 0.21 0.21 room >258,000 -- -- -— 52 800 100 0.2 8T-T2- 100.0 800 82,000 0.31 nil 0.24 0.24 room 268,000 261.000 2.0 2.8 28.8 53 800 100 0.5 4P-T5 100.0 800 00,000 0.40 0.03 0.51 0.54 room >264,000 -- -- -- 278 50 800 100 1.0 6L-T6 100.0 800 115,000 0.43 nil 0.94 0.94 room 267,000 246,000 1.5 3.0 298 51 800 100 2.0 SC-T4 100.0 800 117,000 0.46 nil 1. 16 1.16 room 262, 000 260,000 1.0 1.7 272 52 900 10 0.2 4E-T3 10.0 900 45,000 0.18 nil 0.23 0.23 room >248,000 -- -- ---- 49 900 10 0.2 8T-T4 10.0 900 45,000 0.18 nil 0.27 0.27 room 254,000 246,000 2.0 4.0 281 51 900 10 0.5 6H-T4 10.0 900 58, 000 0.22 nil 0.52 0.52 room 244,000 237,000 2.5 5.7 27.2 51 900 10 1.0 5T-T5 10.0 900 66,000 0.28 nil 0.70 0.70 room 251,000 242,000 1.0 2.2 3.1 51 900 10 2.0 5Q-T5 10.0 900 75,000 0.30 0.02 2.09 2.11 room 246,500 231,000 5.0 7.8 281 49 600 100 0.2 6S-T4 100.0 600 153,000 0.61 nil 0.15 0.15 600 206,000 196,000 8.5 21.1 264 49 600 100 2.0 744B-T6 100.0 600 181,200 1.02 0.0. 3,66 3.96 600 220,000 220,000 2.5 10.9 26 6 49 800 100 0,2 4B-T3 100.0 800 82,000 0.33 nil 021 0.21 800 185,000 177,000 13.5 23.9 255 51 800 100 2.0 6D-T4 100.0 800 117,000 0.51 0.05 2.73 2.78 800 174,500 174,000 14.0 29.4 250 52 900 10 0.2 6S-To -10.0 900 45,000 0.19 nil 0.32 0.32 900 137,000 126,000 13.5 35.5 237 47 900 10 2.0 4K-T3.10.1 900 75,000 0.28 nil 2.49 2,49 900 137,000 135,000 21.0 45.0 20,4 51

TABLE 5 EFFECT OF PRIOR CREEP-EXPOSURE ON COMPRESSION PROPERTIES OF 17-7PH (RH 950 CONDITION) Compression Properties Actual Exposure Conditions After Exposure Nominal Exposure Conditions Total Plastic 0.2% Offset Compression Tlemp. Time Creep Def. Time Temp. Stress Load. Def. Load. Def. Creep Def. Total Plastic Test Temp. Yield Strength Modulus, E ('F) (hrs) (%0) Spec. No. (hrs) ('F) (psi) -(/) (%) (%0) Def. (%) ('F) (psi) (106 psi) 600 100 0.2 4H-T6 100.0 600 153,000 0.56 nil 0.16 0.16 room 215,000 30.0 600 100 0,2 6S-T2 100. 0 600 154,000 0.68 nil 0.34 0.34 room 235,000 30.1 b00 D00 2.0 5-C-T3 100.0 600 181,000 1. 02 0.30 1.84 2.14 room 223,000 29.8 800 100 0.2 6T-T3 100.4 800 82,000 0.34 nil 0.23 0.23 room 263,000 31.9 800 io00 0.5 5C-T2 100.0 800 100,000 0.37 nil 0.45 0.45 room 247,000 30.4 800 100 1.0 4K-T5 100.0 800 115,000 0.43 nil 1.07 1.07 room 261,000 31,6 800 100 2.0 5J-T5 100. 0 800 117,000 0.49 0.08 1.70 1,78 room 258,000 30,0 900 10 0.2 5Q-T6 10.0 900 45,000 0.19 nil 0. 27 0.27 room 264,000 30.5 900 1 0 0.5 4P-T2 10.0 900 58,000 0.24 nil 0.38 0.38 room 259,000 32.7 900 10 1.0 6H-T5 10.0 900 67,000 0.27 nil 1.04 1.04 room 253,000 31.6 900 10 2.0 6L-T3 10.0 900 75,000 0.32 0.02 2.51 2.53 room 246,000 29.3 600 100 0,2 5T-T4 100,0 600 153,000 0.57 nil 0. 11 0.11 600 187,000 30.4 600 i00 2.0 6F-T2 100.0 60.0 - 181,200 i. 11 0.36 1.75 2. 11 600 162,000 28,8 -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - — f~. __ _ ~ _ __ -._~._ __ _ _ __ _ __ _ ^ _ ~ _ ~ ~ _<_ _ _ __ - ^~ __ _ __ _ _ __ ^ __ __ _ __ __ ~ _ _ __ _~,.^ _ __ _ _.__ _~ ^ ~ _ __ ^ _ 800 100 0.2 4B-T1 10.0 800 82, 0.3 nil 020 0.20 800 188,000 00029.1 900 10 0,2 6D-T3 10.0 900 45,000 0. 19- 0.03 0.29 0,32 900 131,000 21,4 900 10 2.0 4E-T1 10.0 900 75,000 0.29 nil 2.36 2.36 900 119,000 22.7

TABLE 6 EFFECT OF SPECIMEN ORIENTATION ON ROOM TEMPERATURE MECHANICAL PROPERTIES OF CIIOM AFTER 10 HOURS PRIOR CREEP —EXPOSURE?AT 700'F Ex[poeuro Cotditiona Total- Room Temperature Short-Time Mechanical Pro eolies After Exposure Total Pla tic Plantic -'- Ult. T/eaele'0'. 0rfet Temp. Time Streav Load. Doi. Lod,. Dot, Creep DeO. Strain Type of Strength Yield Strength Elongation Reduction ot Mod lus, E HarNtuaeg Spen.No,'F) ~~~(hral (Rai) _Jj, I. i. 1.. Teat __jpsi fps1i %~tan) Area% Jjpai) 01A"C0! Speclmena Taken in Rolling Direction (avg. ofat 91 nolt exposed -- - -- -- -- Tensille 146,200 142,900 22.4 31.3 16, 5 33.4 (avg, of 9) not exposed -- - -.- -- Comp. -- 108,000 -- -- 16,Z -- ICD15 700 10none -- -- -- Tensile 143,000 140,000 23. 8 34.0,t,1.4 3.9, 1 3CD33 700 10 none..- -- -- -- Tensile 146,000 -- 24.0 27.9 15.4 38.7 IA4 700 10 56,000 0.43 nil 0.12 0.12 Tensile 138,000 135,000 21.0 30.0'14.7 38.5 3ABS 700 10 79,000 0.62 0, 10 0. 17 0.27 Tensile 149,000 144,000 23.2 31,4 15.5 36.0 2AB16 700 10 93,000 1,77 1.07 0.96 2.03 Tensile 150,500 149,500 21.0 31.2 10,2 37.9 3CD14 700 10 100,000 3.76 3.00 5.44 8.44 Tensile 177,000 175,000 7.8 18.2 A5.6 34.2 IC024 700 10 noane - - -- -- Comp. -- 147,000 -- -- 16.1 3CD9 700 10 none -- -...- - Comp. -- 136,000 -- -. 15. ICD33 700 1 56,000 0.43 alt 0.11 0.11 Comp. -. 125,000 -- -. 6.4 2A2 700 10 82,000 0.62 nil 0,32 0.32 Comp, -- 115,000.-. 15.3 3C27 700 10 90,500 1,27 0.58 0.66 1.24 Comp. -- 94,400 -- -.. 16.8 IABI8 700 10 92,000 2.16 1.45 1.43 2,88 Comp. -- 103,000 --.. 16.6 Specimens Taken 30' to Rolling Direction S4A-T32 not exposed --.-.. -- -- Tenaile 142,400 140,800 29.0 43.7 13.8 34 S4A-T37 not exposed.-.- - -- Tensile 140,000 138,000 26.0 36.2 13.7 36 1411,200 139,400 27.5 40.0 13.8 35 S4C-CII not exposed -. -- -- Comp. - 1410,500 -- -.- 19.0 - S4C-C14 not exposed -- - -. - -- Comp. -- 143,200 --. 18.7 141,850 - -. 10.9 S4A-T30 700 10 one. -. -- Tensaile 139,000 139,000 27.5 45.5 14.5 S4A-T36 700 10 80,000 0.98 0.33 0.47 0.80 Tensile 146,000 146,000 25.5 40.6 14.5 S4A-T35 700 10 88,000 3.97(eost) 3.0 (eat) 1.71 ) 4.70(eat)Tenaile 162,500 162,500 11.0 35.5 14.7 S4-C-C12 700 10 none -.- -- -- Comp. -- 140,000 -- - 16.8 S4C-C13 700 10 none -- -- - -- Comp. -- 141,000 1. - 6.8 S4A-T31 700 10 80,000 0.96 0.25 0.47 0.72 Comp. -- 112,000 --.- 15.4 S4A -T33 700 10 88,000 1.90 1.22 3.34 4.56 Comp, -. Specimenaa Taken 45' to Rolling Directiox S4C-TI not eepoasedr - -.... -- Tensile 136,200 134,400 20. 5 49.7 15.1 30 S4C-T7 dot exposed -. -... Tensile I31,000 -- 27.0 46.2 14,7 35 S4C-T5 not exposed "- --.. -- Tensile 136,200 129,900 19.0 46,3 15.1 36 134,500 132,200 22.1 15.7 14.9 33,3 S4C-CI not exposed --.- -- -- -- Comp. -- 147,700 -- -.- 18.2 - S4C-C3 not expoaed -....- -- -- Cmp. -- 49, 500.... 11.3148,600 -- -- 18,2 S4C-T10 700 10 none - -- -- -.- Tensile 136,000 135,000 26.5 49.0 14.6 36 S4C-T6 700 10 75,000 0.99 0,40 0.34 0.74 Tensile 150,000 150,000 22.0 44.5 14.9 S4C-T3 700 10 90,500 3. 15 2,5 (eat) 2.00 4.5 (et)'Tenaile 160,700 159,000 8.5 37,0 15.6 37 S4C-C6 700 10 none.-.- -- -- Comp, -- 150,500 -- -- 17, 0 S4C-C4 700 10 none - -- - -- Cmp. -- 148,000 -- -- 19.9 S4C-T2 700 10 78,000 1.00 0.39 0.37 0.76 Comp. -- 121,500.- -- 15. 2 S4C-T9 700 10 88,000 4.5 (eat) 3.8 (ea0) 4.10 7.9 Coip. -- 118,000 -- -- 15.0 - Specimrena Taken 60' to Rolling Direction S4A-T67 ot exposed -- - -- -- Tenaile 146,000 120,500 21,0 39.4 13.6 35 S4A-T60 nrt expoeed. — -- - - -- Tnsaile 145,000 139,000 11.0 14. I 13.9 36 145,500 129,750 16,0 26. 7 13.8 35, 5 S4C- C8 not expoed.- -- -- -- -- Comp. -- 160,500 -- -- 19. 3 S4C.CI0 not expoased -- -- -- -- - Comp. -- 164,000 -.-. 22.3162,250 --.. 20. 8 S4A-T65 700 10 none -- -- -- -- T'nuile 144,100 144,000 15.0 16.3 15.2 B4A-T61 700 10 80,000 0.g90 0.40 0.41 0.81 Tenaile 133,000 153,000 18.5 40.8 15.2 S4A-T66 700 10 88,000 1.15 0.48 0,76 1.24 Tenseile S4C-C7 700 10 none -. -- -- -- Comp. 151,000- -- 16.4 S4C-C9 700 10 none *- -. -. Comp. - 162,000 -- - 17.7 t4A-T64 700 10 80,000 0.89 0,24 0.39 0.63 Caomp. - 119,000 -- - 16.6 S4A-T62 700 10 90,000 1.48 0.78 1.37 2.15 Comp, -- 8[nccimenu Talkn 90' to Roiling Direction T44 not exposed. — -. -- -- -- nil 149,000 134,000 21.0 29.8 15,8 37.9 T43 not exposed -- -...- -- Tnile 145,500 131,000 21.8 33.0 16.0 37.0 147,2.50 132,500 21.4 31,4 15,9 37,4 T41 not exposed - - -- - -- Cop. -- 162,000 - -- 16.3 - T42 not 0xpoud -- - -- C p. - - 1i 53,000.. -. 16.9 — 157,500 -- -- 16.6 -~ T4-AT5 70 10 none. — -- -- --'eil 156,200 152,000 27.5 33,6 15.9 36 T4A-T6 700 10 90,500 0.3t 1.20 0.38 0,58 o anouili 162,500 162,500 19.0. 33.3 16.6 35 T4A.T8 700 10 96,000 1.37 0.80 0.90 1,70 Teooilu 166,300 166,100 19,0 19.7 16.6 T47 700 10) none --.- - -- Co., -- 161,500 -- -- 16.1 T4A-TIO 700 I1) 92,000 0.96 0.35 0, 19 0, 8-1 Comp. -- 114, 500 -- - 17. 0 T4A-T7 700 10 97,000 1.05 0.,5 0.72 1.,17 Comp. - 146,000.. -- (6.0 --

TABLE 7 X-RAY DIFFRACTION STUDIES OF 17-7PH (RH 950 CONDITION) BEFORE AND AFTER CREEP-EXPOSURE AT 800*F Mechanical Properties of Specimens Ult. Tensile Strength Yield Strength Elongation Reduction of Modulus, E Hardness Spec. No. Condition (psi) (psi) (%) Area (%) (106 psi) R"C" G-1 (Fig. 10) As Treated (avg. values) 237,650 222,480 8.2 15.0 28.7 48.2 G-2 (Fig. 11) 100 hr creep at 800-F - 115,000 psi 267,000 246,000 1.5 3.0 29.8 51.0 (6L-T6) (yielding 0. 94% creep deformation) A. Hull-Debye-Sherrer Powder Pattern (114. 6 mm diameter camera) Spec. No. G-1 Measured "d'" Values "d" Values for Martensite (from literature) I"d" Intensity "d"l Intensity (hkl) 2. 03 S 2. 035 1 110 1.44 M 1.44 0.4 200 1. 17 MS 1.175 0.8 211 B. Phragmen-Type Camera (Solid Samples) Identification Spec. No. G-1 "d" I Spec. No. G-2 "d" I Martensite? 2.41 VW {identical to G-1) _ _ / 2. Y7 VW ___ 2'07- _____o _,_''_ 2, 03 VS __- - - 1.80 W _ 1.44 M _. 1.29 M 1. 17 M _________ V Notes: "d'" - interplanar spacing I - Inteni.Ity, i.e., Very Weak, Medium, Very Strong, etc. (hkld)- Miller indices of diffracting plane * - possibly CrC lines

"(uoTtpuoD 056 HH) HdL-LI p a.,.-V jo jU9Js PT[.o uoT ssoiadmoD uo soTnlpjaduij.aj, sa jo l:,Jjji ~ ojan~,if, - on I X duma j, s a 1 006 008 00. 00 9 0 09 00I7 0O[ 0070 001 0 0 011 ---- __ -- 07 091 1 -C \-S 1 XX091 0 0 <8, 4 ) 1 08 I ------- - OLo -I-.- --- f - ----- ~ I - I i061 m 0 0 N

o 270.._.. i260 1 — tlh 250 r-_ 240I L — _'......"'.... 20 /^ Code I O 600 ) Exposure h 230 A 800 * ) TemperatureF OF P4 0: 900' ) 0 tn U/ nexposed, (average value for 7 tests)' ZQ220 —-- 250 A bfl Z40:g o "/o *^ 0 10'^ 20 —~ —40 —50 -0 o — 8090 bi 6 U) \_________ 1 A1 ___""""'^ —-.-.,-40 40 0210 —0-30 40 50-60-7-i80 -90 — 00 Exposure Time - hours Figure 2, Effect of Unstressed Exposure at 600', 800, or 900*F on Room Temperature Tensile Properties and Hardness of 17-7PH (RH 950 Condition),

'oa an~.P.JT oduiaL aansodx[ 1V (uotITpuoD 096 HH) HdL-LI JT0 Sl"iaadoaTd TSulJj uP dJ00'.006'.009 l e oansodx- pssajlUe3fn jo;)JJ:O I oanT, sJnoq - au-Tlj, oaJnsodx3 0 - -- -- --- _ —A-'j- — 1 ---- ---- ---- ---- ---- ---- — I I -- ---- --— I —-! - E0 1....... --— F~ —~... 7 (s^sp4 9 zOJ anT^A 90,5JA^.) pasodxaun/ - - -, - - - - -n- a _nad _,:saj; (,006 0 --- -- -- / OZI Pu. (.008 v /J t0. 1 a..nlj.aduaj, aJ-inodxa (.009 0 / 1 0 081 0 _1 I H OH _ I I o ID -- - _- — ~ ~~ —T ~_..-._,. -. —. - _ -- _, -- _ ______ --- --- --- 09 1 L 0___________ —__ — ______ ___ ooz061 0Z o —-----—' —-—'-"- O ---------— ~~ —----— ___ —--— _______! 01Z

o 270 a I I oo^900'F a h 260 /- 800 1 1 r' 50 600. U - 240 _ *t --- + — o - 60C-0 ) Exposure -____ _____ ____ ~ ~ ~ ~ ~ ~ 9o 00 230 / Unexposed (average value for 7 tests) 220 - 0 10 20 30 40 50 60 70 80 90 100 10 120 Exposure Time -hours Figure 4 Effect of Unstressed Exposure on Roo00 ) Temperature om pressFon Yield Strength of 17-7PH (RH 950 Condition).

220 — 0 1 ___ — _ a -- -; 1 1 04 4-i l X Code ^~ ~ 160l l _ — -- - -- — 600 ) Exposur Temperature | 1 500 ) Test TTperature n (average vle for 6]7 140 __ _ i~' Code 0 10 20 30 40 50 60 70 80 90 100 110 600 ) Exposure Temperature Figure 5 Effect of Unstressed Exposure at 600 8 or 9 F and 0 _900 ) Test Temmperature,. F / Unexposed (average value for 6-7 tests) 90 - 0 10 20 30 40 50 60 70 80 90!00 It0 Exposure Time - hours Figure 5. - Effect of Unstressed Exposure at 600e, 800* or,900'F on Compression Yield Strength of 17f7PH (RH 950 ) At Exposure Temperature.

100 hr Prior Creep at 600'F 100 hr Prior Creep at 800'F 10 hr Prior Creep at 900~F - 260 - 26 0.260 -- - -60 0 / 0 2'50 20 - z50 2 0 2 10 2 0 24 240 240 l. to j 27 0 Com pression7 a O 260 0...t -i'- 260 0 —O.. _- Q 260 -_' Compression ~ g7T1ension Tensio 250 -250 0- -250' o L,240 ^^ 7 _ ___ _ _240-_ Code240 T — _'Tension 20 1 0 — Co 0 1m0 p-r -e 20 -0, O3 20 —--- ----- - 20 —-— Tensile Properties 0 I0: o' i 0 10 - o 1.0 1,0 0 0 1,0 2,0 0 0 i= O I \"0 ~-''' ~-10= Go 1 G ^ -~I -ZG( -~-o - _ 0L - )2; reep Defor percent Creep Defomat percent reep Dermation perce2, 0 Creep Deformation - percentCreep Deformation - percent Creep Deformation 6percent Figure 6, - Effect of Prior Creep-Exposure on Tension and Compression Properties of 17-7PH (RH 950 Condition) At Room Temperature,.

100 hr Prior Creep at 600~F 100 hr Prior Creep at 800~F 10 hr Prior Creep at 900'F 230 ------— 200 ---------— 170 _20 _ I _ _ ~~~~~~~~~~~~~~~~~ M' 1-0 0 _ 0 - 190 [ _ ---'> 220 — r. — -- - -- - 0 18 - -0 o 200 1701- 140 ) 210 -- -- --- -- -- -- -- -- Cl 180 ---- -- ---- ---- ---- ---- o 150 - --- --- -— ___ ___ o'. ~........~ ~.~.~o t I I.....i9 0 16013 0 0"1 0 1,0 2.0 3.0 4,0 150 0 1.0 2.0 3.0 0 1.. 3,.- zz0. 1 -~601 —i o - ^ i e^" a~ ~. Compression 1 I ^i2'0!- ^,-^ ^- IC) *80 50. 1 4o1Z _ 1 o150- 1 2 | O 1 [701 Code I I140 — 0 S w,0 / --------------------------------- 0 140ompression I o1~ --.....Tensile Properties 19 j~,,0 *t j,,,' 16 Compression Yield \ T 170 — 60 i- 1,.130 /0 Compress'".......( 17 _ _ ___ ___ I ___ ___J IC_ I ========= g 1 I! 60 10....................Compen Ih ol —. — ~~~~~~0 61 0 _ _ _ "- I - I_ 1_ _~-'_ = 0~ 1, 0 2,~~~ 0 3~0 4,0 0 1.0 2. 0 3.0,00 20 -0z C _ _ _ _ _ _ _ _ I o ------ ----- ----- ----- ------ -.0 — < ------ ------ - - ------—, - -. 0 0- ------ ------ ------ ------ ------. I. F i _ _ _ 0_ I -— _ 1_ I_ _ _ _ __ — i. i_ _ _ _ __^ _ _ _ __^^ ^ ^J - _ _ _ *.i. L ^ L ^ ^ 0 1,0 2.0 3.0 4.0 0 1.0 2,0 3, 0 0 1 0 2,0 3,0 Creep Deformation - percent Creep Deformation - percent Creep Deformation - percent Figure 7. Effect of Prior Creep-Exposure on Tension and Compression Properties of 17-7PH (RH 950 Condition) At Exposure Temperture

160[ 150 ------- Ultimate? 140A -A-_ —-Tension Yield -- 0 0 1(f 0 -__ __ _ _ - _ __ t.,,16~~~~0| __Compression Yield., 17 I 150 e -- - V —- -- < 140-| AT 7 ---- a130 ___ 100 r o 4 ed0ction YieX "0 N 10' I 1 $ Tension'Yiold - 0 10 20 30 40 50 60 70. 80o 90 est Direction with Respect' lto Rolling Direction - degrees 3igure 8, Effect of Specimen Orientation with Respect to Sheet R olling Direction on Room'remperature Mechanical PropJerties of C1rOMo

10 Hours Prior Creep at 700*F 0- to Rolling Direction 30' to Rolling Direction 45, to Rolling Direction 60- to Rolling Direction 90' to Rolling Direction 8 10 -- 180 180 180 170 170 0 170' UO loO ------— 0L -- ---- -- - 160 -16 160 -- l5!i150 i- 0- 1 ~ -O —----- - 15 0 ^ 1./ 0jt 3 1300 130!..130~ 1300 1.0 2.05.0 6.0 0 1.0 2,0 0 1.0 2. 0 0 1.0 2.0 0 1.0 2.0 _o180 —--------------— 180- 180 - -- 180 —- -- 1807 - 170 --- -- -- -I- 170 174 -- 170 - 1'Tension 1 _, 1 1 60 - i.-0 —-—, 0 -- - - 160 -1.-0 - 160b 0- 160 16 — -- -- - l o2., — enion Tension ensionTe C).I0 0E \ os Compression, i _ — - - 30\t \ g I30-e —- ---- ---- ---- -- -_ 130 - 10 10-..0.2mpe 120 1 Cmrsin0 12 120 - - - 1o0' —---- -----— 10 110 — Compression — -- -- 10 \I 1001 _ _ 0-r Unexposed 90.10 20. 0 00 0 6. 2.0 2 4. 0 1.0 2..0 0 1.0 2.0 91 0I 3 I, o I - 30 - - 0 _ __II o__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ____ _ _ I C ____ _ r 10 0 10 J __ 1.0... 0 - - J- - 0 i. 0 2. 0 5. 0 6. 0 0.0 6 0 0 1.0 2. 0 0 1.0 2.0 0 1,0 2.0 Creep Deformation - percent Creep Deformation - percent Creep Deformation - percent Creep Deformation - percent Creep Deformation percent Figure 9 o - Effect of Specimen Orientation with Respect to Sheet Rolling Direction on Room Tenmperature Mechanical Properties of C110M After 10 Hours Prior Creep Exposure at 700'F.

Marble s Reagent X1000 Figure 10. 17-7PH (RH 950 Condition) As -Heat Treated. Marble's Reagent X1000 Figure 11, - 17-7PH (RH 950 Condition) Exposed 100 hr at 800*F and 115,000 psi (0.94% Creep Deformation)