WADC TECHNICAL REPORT 57-150 Part III EFFECT OF PRIOR CREEP ON MECHANICAL PROPERTIES OF AIRCRAFT STRUCTURAL METALS Part III: - C110M Titanium Alloy Jeremy V, Gluck Howard R. Voorhees James W. Freeman Engineering Research Institute The University of Michigan January 1958 Materials. Laboratory Contract'No. AF 3'-3(46)-3368 SuApjlnemct' ( 1(73-850) Project NQo 7360 Wright'Air Developrent Center Air Research and Development Command United States Air Force Wright-Patterson Air Force Base, Ohio

FOREWORD This report was prepared by the Engineering Research Institute of the University of Michigan under USAF Contract No. AF 33(616)-3368. The contract was initiated under Project 7360 "Materials Analysis and Evaluation Techniques," Task No. 73605 "Design Data for Metals," with Mr. E. L. Home acting as project engineer for the Materials Laboratory, Directorate of Laboratories, Wright Air Development Center. The report covers work conducted from January 10, 1957 to December 31, 1957. The research is identified in the records of the Engineering Research Institute as Project No. 2498. WADC TR 57-150 Pt III

ABSTRACT A study was carried out of the effect of exposure to elevated temperature creep conditions on the subsequent mechanical properties of C110M, an 8 percent manganese binary titanium alloy. Exposures were conducted for times of 10, 50, or 100 hours either unstressed or at stresses causing up to 3 percent total deformation at temperatures between 650' and 800-F, Specimens were taken parallel to the sheet rolling direction, Following the exposures, short-time tensile, compression or tension-impact tests were run at either room temperature or the temperature of exposure. Prior creep-exposure was found to have little effect on the fracture strength or ductility in either tensile tests or tension-impact tests. The original material had an abnormally high tension yield strength and a low compression yield strength. Exposure to temperature alone caused a decrease in the tensile yield strength and an increase in the compression yield strength depending on the exposure time and temperature, and on the test temperature. Plastic deformation either during loading, or principally during creep, resulted in an increase in the tensile yield strength and a decrease in compression yield strength from the values established by exposure to temperature alone. This behavior can be attributed to a Bauschinger-type effect. PUBLICATION REVIEW This report has been reviewed and is approved, FOR THE COMMANDER: RICHARD R. KENNEDY Chief, Metals Branch Materials Laboratory WADC TR 57-150 Pt Inl iii

TABLE OF CONTENTS Page INTRODUCTION 1 EXPERIMENTAL PROGRAM..... 2 TEST MATERIAL..... 3 TEST SPECIMENS..... 4 TEST EQUIPMENT AND PROCEDURES,... 5 EXPERIMENTAL RESULTS...... 6 ESTABLISHMENT OF EXPOSURE STRESSES..... 6 BASE PROPERTIES BEFORE CREEP EXPOSURE..... 7 Tensile Properties,..... 7 Compression Properties......* 8 Tension-Impact Properties.. *. *.. 8 Hardness Properties..... 8 TENSILE PROPERTIES AFTER EXPOSURE....... 9 Unstres3ed Exposure........... 9 Room-Temperature Tests........ 9 Elevated-Temperature Tests....... * 9 Creep Exposure... * o g... * * * 9 Room-Temperature Tests........ 9 Elevated-Temperature Tests......, 11 COMPRESSION PROPERTIES AFTER EXPOSURE...... 11 Unstressed Exposure. O... 12 Room Temperature......... 12 Elevated Temperature......... 12 Creep Exposure.. O.. l I 12 Room Temperature..... 13 Elevated Temperature..... 13 TENSION IMPACT PROPERTIES AFTER EXPOSURE.... 14 Unstressed Exposure *. *.... 14 Room Temperature......... 14 Elevated Temperature.....,,.15 Creep Exposure........... 15 Room Temperature...... 15 Elevated Temperature...... 15 RELATIONS BETWEEN TENSION- AND COMPRESSION-YIELD STRENGTHS............. 16 Check Tests on Effect of Unstressed Exposure on C110M. 19 METALLOGRAPHIC EXAMINATION....... 23 DISCUSSION............. 24 CONCLUSIONS............ 26 REFERENCES............. 27 APPENDIX I - STATISTICAL INVESTIGATION OF TEST DATA,. 86 WADC TR 57-150 Pt III iv

LIST OF TABLES Table Page 1. Total Deformation Data and Retained Tensile Properties at Room Temperature for CO10M. * * * 28 2, Tensile Test Data for CI1OM As Produced,, 29 3. Compression Test Data for C11OM As Produced., 30 4. Tension-Impact Test Data (Smooth Bar) for As-Produced C11OM 31 5. Effect of Unstressed Exposure on Room Temperature Tensile Properties of C11OM.... 32 6. Effect of Unstressed Exposure on Elevated Temperature Tensile Properties of C1OM., *. 33 7, Effect of Prior Creep-Exposure on Room Temperature Tensile Properties and Hardness of C11OM... 34 8. Effect of Prior Creep-Exposure on Elevated Temperature Tensile Properties of C110M I. s.. 4 35 9. Effect of Unstressed Exposure on Room Temperature Compression Properties of C110M I.. * * 36 10. Effect of Unstressed Exposure on Elevated Temperature Compression Properties of C11OM.... s.. 37 11. Effect of Prior Creep-Exposure on Room Temperature Compression Properties of C110M *. l I * ** 38 12. Effect of Prior Creep-Exposure on Elevated Temperature Compression Properties of C11OM * *.* *..* 39 13, Effect of Unstressed Exposure on Room Temperature Tension-Impact Properties of C110M.. 40 14. Effect of Unstressed Exposure on Elevated Temperature TensionImpact Properties of C110M.......... 41 15. Effect of Prior Creep on Smooth Specimen Tension-Impact Properties of C 110M......... 42 16. Comparisons of Original and Check Test Tensile and Compression Data for Two Heats of C1 1OM Titanium Alloy..... 43 WADC TR 57-150 Pt III v

LIST OF ILLUSTRA TIONS Figure Page 1. Sampling Procedure for Sheets of C 10M Titanium Alloy., 44 2, Details of Test Specimens... * 45 3. Stress Versus Time to Reach Indicated Total Deformation for C1 OM at 650~, 700' and 800~F..,... 46 4. Effect of Test Temperature on Short-Time Mechanical Properties of As-Produced C110M.......... 47 5. Tensile Test Stress-Strain Curves for As-Produced C1IOM, *0. 48 6. Compression Test Stress-Strain Curves for As-Produced C110M, 49 7. Effect of Unstressed Exposure at 650', 700', or 800'F on Room Temperature Tensile Properties of C 1lOM.. 50 8. Effect of Unstressed Exposure at 650', 700', or 800'F on Elevated Temperature Tensile Properties of C1IOM.... 51 9. Effect of Prior Creep Exposure at 650'F on Room Temperature Tensile Properties of C1IOM...... *52 10, Effect of Prior Creep Exposure at 700~F on Room Temperature Tensile Properties of C1IOM...... 53 1 1. Effect of Prior Creep Exposure at 800~F on Room Temperature Tensile Properties of C110M....... 54 12. Summary of Effect of Prior Creep Exposure on Room Temperature Tensile Properties of C1IOM...... 55 13. Effect of Prior Creep Exposure in Hardness of C1IOM. 56 14. Representative Room Temperature Tensile Test Stress-Strain Curves of C 1OM after Prior Creep Exposure,. 57 15. Effect of 650F Prior Creep Exposure on 650'F Tensile Properties of C110M............ 58 16. Effect of 700'F Prior Creep Exposure on 700'F Tensile Properties of C11OM........... 59 17. Effect of 800~F Prior Creep Exposure on 800'F Tensile Properties of C11OM............. 60 18. Summary of Effect of Prior Creep Exposure on Elevated Temperature Tensile Properties of C110OM,....... 61 19, Representative Tensile Test Stress-Strain Curves at Elevated Temperature for C11OM after Prior Creep Exposure.. 62 WADC TR 57-150 Pt III vi

LIST OF ILLUSTRATIONS (Continued) Figure Page 20. Effect of Unstressed Exposure at 650', 700~, or 800F on Room Temperature Compression Yield Strength of Cl10M... 63 21, Effect of Unstressed Exposure at 650~, 700-, or 800F on Elevated Temperature Compression Yield Strength of C11OM,,, 64 22. Effect of Prior Creep at 650F on Room Temperature Compression Yield Strength of C 1OM * 65 23. Effect of Prior Creep Exposure at 700'F on Room Temperature Compression Yield Strength of C110M..... 66 24. Effect of Prior Creep Exposure at 800GF on Room Temperature Compression Yield Strength of C11OM..., 67 25. Summary of Effect of Prior Creep Exposure at 650', 700G or 800F on Room Temperature Compression Yield Strength of C11 M. 68 26, Representative Compression Test Stress Strain Curves at Room Temperature for C1O1M after Prior Creep Exposure.. 69 27, Effect of Prior Creep Exposure at 650GF on 650'F Compression Yield Strength of C M.......... 70 28, Effect of Prior Creep Exposure at 700GF on 700'F Compression Yield Strength of C110M............ 71 29, Effect of Prior Creep Exposure at 800GF on 800'F Compression Yield Strength of Cl10M............ 72 30. Summary of Effect of Prior Creep Exposure at 650', 700', or 800F on Elevated Temperature Compression Yield Strength of C110M, e e 73 31. Representative Compression Test Stress-Strain Curves at Elevated Temperature Following Prior Creep Exposure, 74 32, Effect of Unstressed Exposure on Room Temperature Tension-Impact Strength of C110M............ 75 33. Effect of Unstressed Exposure on Elevated Temperature Tension-Impact Strength of C110OM.......... 76 34. Effect of Prior Creep Exposure on Room Temperature Tension-Impact Strength of C 110M............. 77 35. Effect of Prior Creep Exposure on Elevated Temperature TensionImpact Strengths of C1OM......... 78 WADC TR 57-150 Pt III vii

LIST OF ILLUSTRATIONS (Continued) Figure Page 36. Effect of Temperature on Compression Yield Strength of C11OM -- Comparison of University of Michigan Data for C 1OM with Data from the Literature.. *...... *. 79 37. Effect of 100-Hour Unstressed Exposure on Room Temperature Tension and Compression Properties of Three Heats of CIlOM.. * 80 38. Tension and Compression Stress-Strain Curves at Room Temperature for Two Heats of C11OM -- Specimens taken longitudinal to the sheet rolling direction............. 81 39. Tensile and Compression Yield Strengths of C1OM at Room Temperature Versus Creep Deformation for Indicated Exposure Conditions *, 82 40. Tensile and Compression Yield Strengths of CI lOM at Elevated Temperature after Indicated Prior Creep Exposure. * * 83 41. Effect of 100- Hour Unstressed Exposure at 8000F on Longitudinal or Transverse Tension and Compression Strengths of Two Heats of C IIOM Tested at Room Temperature. *. 84 42. C 1 0M As -Produced............... 85 43. Cl 10M Exposed 100 Hours at 650~F and 82,000 psi.., 85 44. CO10M Exposed 10 Hours at 700~F and 100,000 psi... 85 45. C 110M Exposed 10 Hours at 800~F and 21, 000 psi. 85 WADC TR 57-150 Pt III viii

)INTRODUCTION The effect of prior creep-exposure at elevated temperatures on subsequent short-time mechanical properties was studied for a binary 8 percent manganese-titanium alloy, C 1OM. The research was conducted as a portion of a program sponsored at the University of Michigan by the Materials Laboratory, Wright Air Development Center, U. S. Air Force, under Contract AF 33(616)-3368. Previous reports issued under this contract have dealt with an aluminum alloy, 2024-T86, (Ref. 1) and a precipitation hardening stainless steel, 17-7PH (TH 1050 condition) (Ref. 2). These materials represent three different types of sheet alloys which might be applied in aircraft structures under conditions which would cause creep during part of their service life. The general purpose of this investigation is to assess the manner by which exposure to the combined effects of high temperature and the creep process could adversely affect the properties of a material for subsequent service. Due to the paucity of information concerning these effects, sufficient background data must be accumulated on representative types of materials before an insight can be gained into the basic principles involved. The need for information of this type has increased as aircraft design and performance requirements have progressed to the point where creep conditions are attained during a portion of the operating cycle. Such creep exposures must not seriously reduce the strength, ductility, or shock resistance of the materials of construction, a) Manuscript released by authors April 18, 1958 for publication as a WADC Technical Report. WADC TR 57-150 Pt III 1

EXPERIMENTAL PROGRAM Three exposure temperatures were selected for the studies of the C110M titanium alloy; 650', 700', and 800~F. The test specimens were exposed for time periods of 10, 50, or 100 hours at either zero stress or at stresses selected to give 0. 5, 1. 0, 2. 0, or 3. 0 percent total deformation in the specified time intervals. Total deformation is defined as all deformation (both elastic and short-time plastic strain) occurring during the application of the load plus the creep deformation of the specimen under the given conditions of stress and temperature. The stresses used in this investigation were those determined to give, on the average, the desired total deformation, since inherent scatter in creep properties causes actual deformations for some specimens to be greater or less than the desired nominal value. Approximately 10 creep tests at various stress levels were first run at each exposure temperature to define the stress-time for total deformation curves used to establish the exposure stresses. It was considered that more consistent data would be obtained if the exposure stresses and times were fixed rather than varying time to obtain exactly reproducible creep strain, Time-elongation data were taken for each exposure test and all correlations of subsequent mechanical properties are presented in terms of the actual deformation. The deformation data are broken down into their various components; total loading deformation, plastic deformation during loading (if any), creep deformation, and total deformation at the end of the exposure period. To evaluate the effects of the exposures, the following tests were carried out: 1. Tensile tests at room temperature and the exposure temperature for specimens exposed either 10 or 100 hours, and at room temperature for specimens exposed 50 hours, 2. Compression tests at room temperature and the exposure temperature for specimens exposed for either 10 or 100 hours, and at room temperature for specimens exposed 50 hours, 3. Tension-impact tests on smooth specimens at room temperature and the exposure temperature for samples exposed 100 hours and and for samples exposed 10 hours at 700F. 4. Hardness determination at room temperature for all tensile specimens. Test specimens were taken in the direction parallel to the sheet rolling direction, the nominally weaker direction of the material. Properties of the specimens subjected to creep exposure were compared to the average properties established for the unexposed material by a series of from five to ten replicate tests intended to define the normal scatter in the given property. For samples subjected to unstressed exposure, duplicate tests were conducted to give more confidence in the results, In a few cases, duplicate stressed exposure tests were conducted, WADC TR 57-150 Pt III 2

TEST MATERIAL Eleven sheets of C1 IOM titanium alloy in the annealed condition were purchased from the Rem-Cru Titanium Corporation. The material was all from heat A 1172600. The sheets were 0. 064 inches thick by 30-36 inches wide by 60-90 inches long. The certified chemical analysis furnished by the producer was the following: Element Percent (weight) Manganese 7.9 Carbon 0. 10 Nitrogen 0. 02 Hydrogen 0. 0093 The manufacturer's reported properties for this material follow: Ultimate Tensile Strength 149,400 psi Tensile Yield Strength 147,200 psi Elongation 15.0 percent Bend 3T WADC TR 57-150 Pt III 3

TEST SPECIMENS Of the eleven sheets of CI 10M received, three were arbitrarily selected for providing test specimens. The test specimens were chosen from among the three sheets to provide a measure of the variation in properties between sheets and within individual sheets. Consequently it was necessary that each specimen be readily identifiable according to its original location, The sampling procedure adopted was designed to permit the most economical utilization of the material consistent with the specification that the specimens be tested in the direction parallel to the sheet rolling direction. The sampling scheme for an individual sheet is illustrated in Figure 1, Each sheet was divided into one-inch wide strips running the length of the sheet. Over the 90-inch length of the sheet four sections or quarters of length were laid out. One end of the sheet was arbitrarily designated the "Al" end and its subsections labeled AA and AB, while the other end was designated wthe "C" end and its subsections labeled CC and CD. Occasionally the AA samples were merely labeled A and the CC samples labeled C. Samples for the initial tests for the determination of base properties were taken from strips 1, 5, 9, etc. as indicated in Figure 1, which were subdivided to provide a repeating sampling pattern over the width and the length of the sheet. The remainder of the strips were reserved for the 22-inch blanks of the specimens to be given creep exposure prior to testing. The individual specimens were stamped with a number sequence designating the sheet number, section number, and the strip number. Thus, the specimen labeled 2CD-17T is a tensile specimen from the CD end of strip 17 from Sheet 2, The details of the various test specimens used in this investigation are shown in Figure 2, All specimens for the tests of mechanical properties 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 of the specimens was machined 0, 030 inches over the 0. 5 inch nominal width. This was machined off after creep exposure. This procedure permitted the measurement of the properties of the material itself unaffected by the particular edge effects, if any, associated with the exposure of the specimen, For ease in machining, jigs were constructed so that five or six specimens could be made concurrently. The blanks were milled to rough dimensions and the shoulder radii and gage sections were then ground to the finished dimensions. WADC TR 57-150 Pt III 4

TEST EQUIPMENT AND PROCEDURES Detailed discussion of the development of the test equipment and procedures has been previously given (Refs. 1 and 2) 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 creep-testing 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 Baldwin-Southwark hydraulic tensile machine equipped with a strain pacer. A strain rate of 0. 005 inches per inch per minute was used. 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. An Olsen impact-testing machine was modified to permit the carrying out of tension-impact tests on sheet specimens. The modifications included construction of holding jaws to permit attachment of the specimens to the pendulum head,extension of the striking surfaces, and the construction of a small split-type furnace for heating the specimens. Specimens prepared for metallographic examination were wet ground on rotating laps using a series of silicon carbide papers through 600 mesh, Finish polishing was accomplished with acqueous media of Linde "A" and Linde "B" polishing compound on rotating laps covered with "Microcloth. The polished samples were etched with a mixture of 1 part glycerine to 1 part hydrofluoric acid, Hardness determinations were made using a Rockwell "C" scale. The value reported is the average of five or six impressions made on shoulders and gage sections of the exposed specimens. WADC TR 57-150 Pt III 5

EXPERIMENTAL RESULTS The results of the exposure tests were correlated with respect to the amount of prior creep, temperature, and time of exposure. In all plots the properties of the unexposed material and the material exposed to time and temperature alone are indicated on the zero deformation axis. Consistent trends in the curves were taken as a measure of significant property changes. A knowledge of the variance of the unexposed material would permit comparisons of property changes with respect to the unexposed condition even if specific confidence limits could not be fixed to the deformation versus residual property curves themselves. This point is discussed further in Appendix I. The complete time-deformation data obtained permitted the separation of the strain into its various components. Consequently, correlations are presented in terms of both the actual total deformations and associated creep deformation obtained in the test. In tests at 650'F, particularly, plastic deformation occurred during loading. This deformation was obtained from the total loading deformation by subtracting the normal elastic strain expected at the test stress. The creep deformation was obtained by subtracting the total loading deformation from the total deformation at the end of the test. Total plastic strain would be the sum of the creep deformation and the plastic deformation on loading. ESTABLISHMENT OF EXPOSURE STRESSES The results of the seven to nine creep tests at each of the three test temperatures, 650', 700', and 800'F, to establish stress versus total deformation characteristics between 10 and 100 hours for 0 5, 1. 0, 2, 0, and 3, 0 percent total deformation are summarized in Table 1. None of the tests were run to rupture, the tests being discontinued once the limit of useful strain had been reached. The discontinued creep specimens were then tensile tested at room temperature in order to determine the effect of the creep on the tensile properties. The subsequent tensile test properties together with the total test time and final deformation are included in Table 1. The stress-time for total deformation curves are presented in Figure 3. The nominal stresses for the required creep were determined from the intersection of the total deformation curves with the ordinate at 10, 50, or 100 hours. In some cases, further experience with the creep exposure tests later necessitated readjustment of the stresses. At 650'F relatively low stresses were required so as not to exceed 0, 5 percent total deformation on loading. Creep at these stresses was very slow. At higher stresses very rapid creep occurred. Estimates of the stress required to obtain 2, 0 and 3. 0 percent deformation on loading were used in order to draw the curves for these deformations at 650~F. At 700' and 800~F little difficulty was encountered in obtaining the desired total deformations in the time interval to be considered. Breaks in the curves apparently exist at each of the test temperatures. WADC TR 57-150 Pt III 6

Samples exposed to creep at 650' or 700'F exhibited instances of increased tensile and yield strength at room temperature, Table 1, with the effect most noticeable for the 700~F samples. The increase in strength was moderate, generally within 15 percent of the base value, and was accompanied by some decrease in ductility. Several specimens exhibited a decrease in yield strength after creep at 800'F, with a sample exposed for almost 1300 hours showing a severe loss of yield strength. The specimens with shorter exposure time periods or larger amounts of deformation suffered less drop in yield strength and even exhibited slight increases in ultimate strength, Some increase in hardness, Table 1, over the as-produced value of Rockwell "C" 33. 4 was observed in a number of the specimens. BASE PROPERTIES BEFORE CREEP EXPOSURE Tensile, compression, and tension-impact tests were conducted in order to establish the average strength of the as-produced material at both room temperature and at the temperatures of creep-exposure. Specimens were taken at random, generally three per sheet, and the results presented as average values within sheets and the average of all tests at the given temperature. The average of all tests was used as the basis for comparisons with properties following creep. Statistical treatment of the base property data is included in Appendix I. Tensile Properties The results of tensile tests at room temperature, 650', 700', and 800'F are summarized in Table 2, A plot of the effect of testing temperature on average short-time mechanical properties is given in Figure 4, with typical stress-strain curves from tensile tests presented in Figure 5, Fairly good agreement in tensile and yield strengths was noted both within sheets and between sheets. Individual tests values at all test temperatures were generally within 5 percent of the average value. Both the tensile and yield strengths showed a decrease with increasing test temperature of approximately the same magnitude, Elongation underwent a slight decrease at 650'F from the room temperature value and then a substantial increase at 700' and 800'F. Reduction of area values are also reported even though such measurements on sheet specimens are not very accurate, A caution should also be added with respect to the modulus values reported in Table 2, These values were computed from the slopes of the stress-strain curves and are not considered as precise modulus determinations. The room temperature tensile and yield strength properties reported in Table 2 were slightly lower and elongations higher than those reported by the manufacturer for the heat (see page 3 ), In both determinations it was apparent that the tensile yield strength was high with respect to the ultimate strength. WADC TR 57-150 Pt III 7

Compression Properties Compression test results at room temperature and elevated temperature are presented in Table 3. A plot of the effect of test temperature on average compression yield strength is included in Figure 4 and typical stress-strain curves from these tests are plotted in Figure 6. The compression yield strength exhibited about the same temperature dependency as did the tensile yield strength although there was some levellingoff tendency to be noted between 700' and 800~F. Indicated modulus values were about the same in both tension and compression. Variation between tests and between sheets was slight, generally not exceeding a deviation of 5 percent from the average value at the particular test temperature. It became apparent during the course of this work that the relationship between the tensile and compression yield strengths was not typical of that previously observed for this material. The average compression yield strengths established for the as-received material were generally about 60 percent of the tensile yield strength at the same test temperature. This was in contrast to a more normal observation of essentially equivalent tension and compression yield strengths. With the approval of the Materials Laboratory, WADC, work was initiated on a study of this discrepancy. The presently available results of this study are discussed in the section on the relations between tensile and compression yield strengths (see page 16 ), Tension-Impact Properties The results of tension-impact tests at room temperature and elevated temperature are summarized in Table 4, and the average tension-impact strength is plotted as a function of test temperature in Figure 2. Some decrease in tension-impact strength occurred with increasing test temperature, Fairly good agreement between average properties of individual sheets was noted; however, individual tests within sheets exhibited scatter. This was particularly the case for room temperature and 650~F tests of Sheet 2, and some elevated temperature tests of Sheets 1 and 3. Hardness Properties The hardness of the material as-received was determined to be Rockwell "C" 33.4. This value is the average of four determinations each on three coupons, each taken from a different sheet of test stock. WADC TR 57-150 Pt III 8

TENSILE PROPERTIES AFTER EXPOSURE Unstressed Exposure Room-Temperature Tests. Room temperature tensile tests following unstressed exposure revealed very little change in properties with the exception of the yield strength following 800'F exposure. The test data are summarized in Table 5 and plotted in Figure 7. Reference to this figure shows that the unstressed exposure had negligible effect on the ultimate tensile strength, while the 650' and 700'F exposures had minor effects on the yield strength. Following exposure at 800'F the yield strength dropped consistently with increased exposure time, reaching a value about 12 percent below the as-received strength after 100 hours of exposure, Elongation values exhibited a slight but hardly significant decline with increased exposure times and temperatures. Hardness first underwent a slight increase and then a levelling-off with longer times at each of the exposure temperatures. Good agreement was obtained in the subsequent tensile tests for the duplicate exposures conducted. Elevated-Temperature Tests. The results of tensile tests at the exposure temperature following unstressed exposure are summarized in Table 6 and plotted in Figure 8. The ultimate tensile strengths were virtually unaffected by exposure to temperature alone. An apparent increase in tensile strength from 800'F exposure was within the variation noted in replicate tests to establish the base strength. The average yield strength after 100 hours exposure at 700'F was about 9 percent below the as-produced, 10 hour, or 50 hour values. At 800'F the yield strength dropped for exposures up to 50 hours and then recovered at 100 hours -- but not to the original value. The maximum loss of yield strength at 800'F was about 19 percent of the base strength at this temperature. The elongation values showed some decrease for exposures up to about 50 hours at each of the temperatures followed by a return to the vicinity of the base value after 100 hours exposure, The agreement between duplicate exposure tests was generally quite good. Creep Exposure Room-Temperature Tests, Tensile tests at room temperature following prior creep for 10, 50, or 100 hours are reported in Table 7 and plotted as a function of both creep deformation and total deformation for each exposure time and temperature in Figures 9, 10, and 11. A summary of the test results for all temperatures is presented in Figure 12,. Hardness data are WADC TR 57-150 Pt III 9

summarized in Figure 13 and representative stress-strain curves from these tests are included in Figure 14. With one exception one test was made for each nominal creep deformation. Conclusions were drawn from trend lines constructed through four test points for varying deformations in each exposure time. At 650'F, Figure 9, a major portion of the total deformation in each test was obtained during loading. Consequently the range of creep deformations covered was rather limited, generally ranging only to about 0, 5 percent even though the associated total deformations were as much as 3 percent. On either a total deformation or creep deformation basis the variations in tensile strength with increased deformation were fairly slight, generally within 5000 psi deviation from a base strength level of 146, 000 psi. Yield strengths tended to show an increase with prior creep with increases as much as 12,000 psi above the strength of material exposed to temperature alone. A correlation on the basis of total plastic strain would lie somewhere between the trend lines drawn on Figure 9. Ductility changes were relatively s light, Considerably greater effects of prior creep on tensile properties at 75'F were found for exposure at 700'F (Figure 10) than were found for exposure at 650'F. Both the tensile and yield strengths showed increases with increased amounts of prior creep. At the larger amounts of deformation the increase in strength over the base condition was 10 percent or greater. At 700'F the loading deformation was a smaller proportion of the total deformation than was encountered at 650'F and the plastic component of the loading deformation was also considerably smaller. Consequently, the range of creep deformations covered was much greater than those studied at 650'F, The elongation values fell off somewhat with increased amounts of prior creep. The results of the tests after creep exposure at 800'F (Figure 11) indicate little or no change in subsequent tensile strength and ductility. The changes in yield strength were the same as those due to the effects of temperature alone. At this temperature a great proportion of the deformation occurred during creep, A creep test specimen exposed for almost 1300 hours at 800'F (see page 7 ) showed a severe drop in yield strength although crept to only 0. 52 percent total deformation (0. 47 percent creep deformation). The summary of the tensile test data presented in Figure 12 indicates that there was some tendency for the longer exposure times at 650' and 700'F to result in increases in tensile strength and perhaps yield strength. There appeared to be no effect of exposure at 800'F on the tensile strength, while the yield strength did appear to be a function of the exposure time rather than the amount of deformation. Although the effect of prior creep on the tensile test elongation was not large, the 100 hour exposures tended to result in lower elongations than did the shorter exposure times, WADC TR 57-150 Pt III 10

Hardness changes as the result of prior creep were relatively minor (Figure 13) and were apparently confined to an over-all increase of some 5 points Rockwell "C" over the base condition. No particular effect could be attributed to the varying amounts of prior creep, while the only effect of exposure time appeared in the 800'F exposure data where the 100 hours exposure had a somewhat lower hardness than the 10 and 50 hours exposures. Elevated Temperature Tests. Tensile tests at the exposure temperature were conducted for samples that had been exposed to prior creep for 10 or 100 hours. The results of these tests are summarized in Table 8, Plots of the data for each exposure temperature and time are given in Figures 15, 16, and 17, with a summary of the data included in Figure 18, Figure 19 presents representative stress-strain curves from these tests. Prior creep at 650'F had little or no effect on the 650'F tensile and yield strengths (Figure 15). As was the case with the room temperature tests, most of the total deformation was obtained during loading and the range of creep deformation covered was quite limited. Some decrease in elongation did appear to result from increased amounts of prior creep. The creep at 700~F did have an effect on the 700~F tensile properties (Figure 16). This consisted of some increase in the yield strength for 10 hours exposure and an increase in both the tensile and yield strengths for 100 hours exposure. In the case of the yield strength after 100 hours exposure, increased creep served to wipe out the loss that occurred from exposure to temperature alone, while the tensile strength showed an increase of almost 15 percent over the base condition. However, the increased tensile strength after the 100 hour exposures was accompanied by a substantial drop in elongation. At the highest percentage of creep studied, the subsequent tensile elongation was less than half the base value. Prior creep for 10 hours at 800'F appeared to have little or no effect on the 800'F tensile properties, while the 100 hour prior creep had an adverse effect on the yield strength. (Figure 17). The loss of yield strength following 10 hours exposure was apparently due to temperature alone. However, the yield strength of material exposed to creep for 100 hours was reduced by 25 percent from the base value. Tensile test ductility in these tests was increased by larger amounts of prior creep. COMPRESSION PROPERTIES AFTER EXPOSURE The compression property evaluated was the 0,2 percent offset yield strength. Modulus values computed from the slopes of the stress-strain curves are also reported. WADC TR 57-150 Pt III 11

Unstressed Exposure Exposure of the Cl10M alloy to temperature alone for periods up to 100 hours was found to cause significant increases in the compression yield strength, depending both on the exposure temperature and the test temperature. Room Temperature. The results of room temperature compression tests on specimens subjected to exposure without stress for 10, 50, or 100 hours at 650' 700', or 800'F are summarized in Table 9 and plotted in Figure 20. With only one exception, that of 50 hours exposure at 700'F, the results of duplicate tests showed very good agreement. For all exposures except that of 10 hours at 650'F, the average compression yield strength was raised from 15 percent to almost 40 percent over the base condition. The increase in yield strength was apparently both temperature and time dependent, with the greatest increase occurring between the 0 and 10 hours exposure at 700' or 800'F. At 650F, the maximum effect apparently occurred between 10 and 50 hours. The strength after 100 hours exposure at either 700' or 800'F dropped off somewhat from the maximum value. The indicated modulus values showed no changes, Elevated Temperature. The results of the compression tests of material exposed without stress and tested at the exposure temperature are summarized in Table 10 and plotted in Figure 21, These data indicate than an increase in elevated temperature compression yield strength resulted from all the 700'F exposures and the 10 and 50 hours exposure at 800'F. Agreement between duplicate tests was again generally good. Exposure at 650'F for 100 hours caused a slight but hardly significant increase in the 650'F yield strength. However, the 700'F exposure resulted in an increase in 700'F yield strength at 10 hours which leveled off as the exposure time was further increased. The 800'F tests showed an increase in yield up to 50 hours exposure followed by a drop-off that left the 100-hour results little changed from the base strength. The maximum increase for 700'F exposure was 37 percent above the 700'Fbase condition, while the maximum increase for the 800'F tests was 28 percent of the 800'F base condition. Modulus values again appeared to be unaffected. Creep Exposure Prior creep at all temperatures tended to reduce the room temperature compression yield strength of C 1 10M from the value established by exposure to temperature alone. In most cases, however, strengths still remained above the base condition. Elevated temperature strengths following prior creep showed less clear-cut effects although some tendency existed for reduction in strength in the 650' and 700'F tests. WADC TR 57-150 Pt III 12

Room Temperature. Room temperature compression tests on samples subjected to prior creep are summarized in Table 11. Plots of the effects of exposure time and temperature are presented in Figures 22, 23, and 24 and summarized in Figure 25. Representative stress-strain curves from these tests are presented in Figure 26. The data indicate that increased amounts of prior creep caused a general decrease in compression yield strength from the value established for exposure to temperature alone. In most cases, however, this did not result in a reduction of strength below that of the base condition of the unexposed material, since the unstressed exposures were previously shown (see page 12 ) to raise the yield strength by significant amounts. However, in the cases of 10 hour prior creep exposure at 650' and 700-F, the final yield strength did fall below the base value when the total deformation exceeded approximately one percent. Although total deformations up to 3 percent were covered in the 650-F exposures, the associated creep deformations were limited to about one percent, (Figure 22). This amount of deformation served to eliminate the increase in strength for the 50 and 100 hours unexposed conditions, while for 10 hours, the strength immediately dropped below the base value. For all three times, the exposure to 0.5 percent creep deformation served to reduce the yield strength some 8-10 percent below the value established for exposure to temperature alone, Losses in yield strength from 700'F exposure to prior creep were generally larger than those found at 650'F (Figure 23). For a given amount of deformation, the severity of the effect was diminished as the exposure time was increased. For 10 hours exposure, approximately 0. 5 percent creep deformation (1, 5 percent total deformation) reduced the strength to the base value for the unexposed condition. For the longer exposure times creep deformations or total deformations of from 3 to 6 percent were required to reduce the strength to the base value. The maximum reductions in strength from the value for zero deformation following total deformations up to 3 percent were 32 percent for 10 hours creep, 22 percent for 50 hours and 14 percent for 100 hours prior creep. In the 800-F exposures practically all the deformation obtained was due to creep (Figure 24). Creep deformations up to 3 percent reduced the yield strength from the zero deformation value. However, for all exposure times the strengths leveled off at between 118-125 percent of the base condition for unexposed material, The maximum reduction in strength from the condition of exposure to temperature alone was 10 percent for 10 hours creep, 15 percent for 50 hours, and only 7 percent for the 100 hours prior creep time, The maximum loss in strength was reached in about 0. 5 percent creep deformation for 10 hours, 1 percent for 50 hours, and 1, 5 percent for 100 hours, Elevated Temperature. Compression tests at the exposure temperature of material exposed to prior creep are summarized in Table 12. As indicated previously, tests were confined to exposure times of 10 or 100 hours. The individual plots of the test data are presented in Figures 27, 28, and 29, and summarized in Figure 30, Figure 31 present typical stress-strain curves for these tests, WADC TR 57-150 Pt III 13

In general, exposure and testing at 650' or 700'F resulted in a loss of strength, while the 800'F tests showed the possibility of a slight improvement in strength over the base conditions. In the 650'F tests (Figure 27) for both the 10 and 100 hour exposures, creep deformations of about 0, 5 percent ( 1-2 percent total deformation) lowered the strength by some 15 percent from the base value for unexposed material. In the 700'F tests, the reduction in strength from that of the material exposed without stress was larger. However, in the ranges of time and deformation studied, the observed minimum strength did not fall below the unexposed base material, (Figure 28). In the 10 hour tests the maximum loss of strength was reached at about 0. 5 percent creep deformation and the strength appeared to level out at a value about 30 percent below that for exposure to temperature alone. The results of the 100 hour exposure tests were not as consistent and were complicated by scatter for the zero stress exposures. Up to 2 percent total deformation (1.5 percent creep deformation) the yield strength apparently fell off with increased deformation, reaching a value about 20 percent below the average value for unstressed exposure for 100 hours. However, the test point for approximately 3 percent deformation indicates a considerable increase in strength. The validity of this point is somewhat uncertain and, therefore, the trend line is indicated as questionable. The 800'F tests (Figure 29) resulted in minor increases in yield strength for intermediate deformations. The data for both 10 and 100 hours indicate an increase averaging about 10 percent over the zero deformation value when the material was subjected to 0, 5 to 1 percent creep deformation. Beyond this initial increase there appeared to be a slight tendency for the strength to drop off with increased amounts of creep deformation. However, the data for 100 hours indicate that almost 7 percent creep deformation did not reduce the yield strength below the initial value. No particular effect appears to be attributable to differing exposure times. TENSION IMPACT PROPERTIES AFTER EXPOSURE Tension-impact tests after unstressed exposure at 650', 700' and 800'F were run at both room temperature and the exposure temperature. Specimens exposed to creep at 700' for 10 or 100 hours were also tested at room temperature and the exposure temperature. However, the tests of material exposed to creep at 650' and 800'F were limited to 100 hours exposure. The tensionimpact tests were conducted on smooth specimens, Unstressed Exposure Room Temperature. Data from room temperature tension-impact tests following unstressed exposure is tabulated in Table 13 and plotted in Figure 32. In general, there was relatively little effect. A considerable amount of scatter was noted between duplicate tests of several conditions and it was not possible to fix clear trends from the data. The data indicate that 100 hours exposure at 650or 800'F tends to raise the tension-impact strength. However, the 700'F data WADC TR 57-150 Pt III 14

show an apparent intermediate effect with a maximum occurring at 10 hours, The availability of only one test point for this condition complicates the drawing of any conclusions. Ductility measurements made on the test specimens were inconclusive, Elevated Temperature. The results of tension-impact tests conducted at the exposure temperature are summarized in Table 14 and plotted in Figure 33. In these tests the reproducibility between duplicate exposures was much better than in the room temperature tests. The data indicate slight but hardly significant increases in 100 hours at 650' and 800'F while an increase of almost 30 percent over the base condition was found at 700'F for 100 hours exposure, with an accompanying decrease in ductility. The ductilities for other exposure conditions were not affected, Creep Exposure Room Temperature. The test results for specimens subjected to prior creep and then tested in tension-impact at room temperature are summarized in Table 15 and plotted in Figure 34. The tests were confined to exposure to creep in 100 hours at 650-, 7000, or 800F and for 10 hours at 700'F Excessive scatter for the 650' exposure and the 10-hour exposures at 700'F made the interpretation of the results quite difficult. For both exposure temperatures it appears that increased amounts of deformation tend to reduce the tension-impact strength below the value for zero deformation, Some of the values for tension-impact strength following exposure at 650'F were reduced to as much as one-half the unexposed strength. On the other hand, the 100-hour creep exposure at 700'F showed an increase in tension-impact strength with an apparent maximum effect at about 1-percent creep deformation. The 100-hour exposure at 800F resulted in a decrease in the tension-impact strength from the increase over the base condition observed for the material exposed to temperature alone. The strength appeared to level off at about the level of the base strength for deformations above 1 percent. Elevated Temperature. Tension-impact properties for specimens tested at the temperature of prior creep are summarized in Table 15 and plotted in Figure 35, These results are limited but show more consistency than did the room-temperature tests following the same range of creep exposure. Very little change from the base condition or the condition of exposure to temperature alone was found for the tests after 100-hour exposure at 650' or 800F or the 10-hour exposure at 700'F. The one condition of unstressed exposure that did result in a significant increase in tensile impact strength at elevated temperature was for 100 hours at 700'F. However, after about 0. 25-percent creep deformation at 700TF, the strength was reduced to the level of the unexposed material, WADC TR 57-150 Pt III 15

RELATIONS BETWEEN TENSION- AND COMPRESSION-YIELD STRENG THS Comments from Republic Aviation personnel on data contained in progress reports on this contract pointed out that the reported compression yield strengths appeared to be too low in relation to the tension yield strengths. These data are summarized in the present report in Tables 2 and 3 and indicate that the compression yield strength averaged about 60-70 percent of the tension yield at each test temperature. Republic cited experience which indicated the yield strengths in tension or compression to be of the same order of magnitude. In order to resolve this discrepancy, a study was undertaken to answer the following questions: 1. Is the compression test procedure used at the University satisfactory? 2. Could the previously reported results be reproduced? 3. Is the apparent discrepancy related to the material and not the test procedure? The major source of information for this study was TML Report No. 43 "An Evaluation of Compression-Testing Techniques for Determining Elevated Temperature Properties of Titanium Sheet" issued by the Titanium Metallurgical Laboratory of Battelle Memorial Institute, (Ref. 4) The compression testing procedures used at the University are in substantial agreement with the practices recommended in TML Report No, 43. These include the use of an averaging extensometer, off-set grooved guide blocks, and a consistent supporting force achieved with the use of a torque wrench. Absolute values of compression yield strength determined with this equipment were compared with data available in the literature for three alloys tested; 2024-T86, 17-7PH (TH 1050), and C110M. Good agreement with reported values was found. The accompanying sketch (Figure 36) compares the absolute values of compression yield strength of C110M determined at the University with those determined at three other laboratories (as reported in TML Report No. 43), This comparison shows the values obtained at the University fall slightly to the low side -- particularly at room temperature -- although the deviation is not excessive. Table 16 summarizes the results of additional tests run at room temperature and 700'F to check the reproducibility of the data. These tests were run at normal support force -- about 2-4 inch-pounds -- with an additional test at each temperature run with a supporting force of 50-60 inch-pounds. The purpose of this was to see if a substantial increase in support force would significantly increase the compression yield strength. The results of all check tests showed excellent agreement with the data originally reported. Increased support force had a slight effect on yield strength. The effect, if any, was certainly not enough to account for the apparent discrepancy with the tensile yield strength. Premature buckling was thus ruled out as a factor in producing low compression strengths. WADC TR 57-150 Pt III 16

Since the study of the procedures and reproducibility of the test data did not resolve the discrepancy, attention was directed towards the test material itself. Examination of available data indicated that the particular heat of C1 10M received for testing had an abnormally high ratio of tensile yield strength to ultimate tensile strength. For heat A 1172600 the ratio varied from 88-98 percent, while data indicated the ratio to vary from 70-90 percent over the temperature range up to 700'F. (TML Report No. 43) This observation led to the suspicion that the low ratio between the tensile and compression yield strengths was due more to an abnormally high tensile yield strength of this heat than to any faults in the compression testing procedures. Partial confirmation of this has been obtained from tests run on samples of RC 130A sheet remaining from the experimental work reported in WADC TR 54-54 "A Study of Creep of Titanium and Two of Its Alloys," The sheet tested was from heat A5036 and was received in the spring of 1952, Thus, it is over 5 years old and may not be representative of current production. The tensile strength of heat A5036 was originally determined to be 129, 000 psi and the yield strength 110,000 psi. The check tests just run indicated a tensile strength of 133,000 psi and a yield strength of 114,500 psi. The ratio of yield strength to tensile strength was thus about 0, 85 which compares favorably with the Armour and Rem-Cru data. The compression strength of this heat was found to be 118,500 psi. For this heat, therefore, the ratio of the compression yield strength to the tensile yield strength shows excellent agreement with the data from TML Report No, 43, The results also increase the confidence placed in the compression testing procedures used at the University. Comparative analyses of the two heats tested follow C Mn N H2 Ten. YS/Ten.Ult. Comp. YS/Ten. YS CI1OM HeatA1172600. 10 7.0,028.0093.98.76 RC130A Heat A5036.10 6.9.018.0083.85 1.03 Apparently the disparity between the tensile and compression yield strengths is an anamoulous one associated with the particular heat of C1 10M (A 1172600) received for testing. In the absence of obvious compositional effects (the oxygen contents are unknown) it appears that the differences between heat A 1172600 and the other heats -- that is heat A5036 and the data reported in TML Report No. 43 -- could be related to processing conditions. It should be noted that heat A1172600 was received in early October 1956 while TML Report No. 43 is dated June 8, 1956 and presumably deals with material produced much earlier than that. Thus, unknown differences in processing conditions, presence of residual stresses, etc. might be present in the latest heat. Arrangements were made with approval of the Materials Laboratory, WADC for Republic Aviation and the University to cooperate to exchange test stock of ClIOM in order to check the other's test results and procedures. WADC TR 57-150 Pt III 17

A supply of blank strips from Heat A117Z600 was shipped to Republic and strip stock from another heat, A50089, was furnished by Republic. Tests were conducted at room temperature in both tension and compression, The results of tests conducted at the University on heat A50089 follow: Tensile Properties Compression Properties 0. 2O%.o 0.. oz% Ultimate Offset Offset Tensile Yield Reduction E Yield E Strip Strength Strength Elongation of Area Strength 6 psi) No. (psi) (psi) (%) (%) (10 psi) (psi) (10 psi) 1 127, 100 110,800 26.8 32,4 14.8 115,800 15.3 2 126,900 111,800 25.8 31.2 14.7 112,200 15.3 3 124, 800 111,000 24.0 29,6 14-.9 111,900 15.3 Avg. 126,267 111,200 25.5 31. 1 18 113,033 15.3 Close agreement was obtained between replicate tests, with the strength values falling well within + 2 percent from their respective average values. The agreement between tension and compression yield strengths was also close, with the former about 1-1/2 percent higher on the average. These results agree well with what might be termed "normal" properties and the relationships between tension and compression yield strengths. To date the results of the tests run by Republic on heat A 1172600 have not been received. It does, however, appear that the compression yield/tension yield ratio of the stock from heat A 1172600 purchased by the University is considerably less than that normally expected for this alloy. Further, unstressed exposure of this material at 800'F for times up to 100 hours increased the compression yield strength and decreased the tensile yield strength. (These data are reported in Tables 5 and 9 of the present report and plotted on Figures 7 and 20. Particularly striking were the data for the 100-hour exposure which resulted in an almost complete reversal of the ratio between the tensile and compression yield strengths. Specimens taken from heats A5036 and A50089 were also subjected to 100 hours unstressed exposure at 800-F and then tested in tension or compression at room temperature with the following results: WADC TR 57-150 Pt III 18

Check Tests on Effect of Unstressed Exposure on CIlOM Room Temp. Tensile Properties Room Temp. Compression Properties 0. %.70 Ultimate Offset Tensile Yield Yield Exposure Strength Strength Elongation Strength Elongation Heat Condition (psi) (psi) (%) (psi) (%) No. As. Rec. 133,000 114,500 14.8 118,000 15.9 A5036 +800F-100 hr 120,000 101,000 15.2 110,000 15.7 As Rec. 126,300 111,200 14.8 113,000 15.3 A50089 +800F-100 hr 141,200 109,200 15.3 115,000 16.1 The accompanying bar graph (Figure 37) illustrates the relation between the room temperature tension and compression properties of material from the three heats of C1 LOM both in the as-received condition and after exposure to 800-F for 100 hours. This figure makes evident that only the as-received condition of heat A 1172600 exhibited the "abnormal" relationship between the tensile and compression yield strengths and suitable heat treatment of this condition would change the relationship, Plotting the tension and compression stress-strain curves for the as-received material from heats A5036 and A1172600 on the same graph (Figure 38) shows a marked difference in the shape of the stress-strain curve between the tension and compression portions for the material from heat A1172600, These curves show a remarkable resemblance to those presented by Templin and Sturm (Ref. 5) which show the effects of unidirectional or polydirectional cold work on 52S aluminum rod. The aluminum rod given unidirectional cold working exhibited a tension curve with a rather sharp "knee" at a stress slightly below the yield strength, while the compression half was much more gradually rounded. The rod given polydirectional work exhibited curves of the same shape for both testing directions. Similar results were obtained by Templin and Sturm for 99, 5% pure aluminum and 24ST aluminum. Such results are a common manifestation of the Bauschinger effect whose very definition in the ASM Metals Handbook (Ref. 6) is "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 " Very strong evidence exists of the presence of a Bauschinger-type effect in the as-received stock of C 110M. WADC TR 57-150 Pt III 19

In view of the above findings, analysis was made of the effects of creep-exposure on the relationships between the tension and compression yield strength. Figure 39 presents simultaneous plots of the tension and compression yield strengths at room temperature following prior creep while Figure 40 presents a similar series of plots for the tensile and yield strengths at the exposure temperature. In these figures the strengths were plotted as a function of creep deformation, although total plastic strain could also have been used. The intersection of these curves with the zero deformation axis indicates the effect of exposure to temperature alone. Also indicated are the strengths of the unexposed material. Examination of these data shows that exposure at the higher temperatures and longer times caused an increase in the compression yield strength relative to the tensile yield strength. The changes in the relative magnitudes of the yield strengths are indicated in the following tabulation: Exposure Conditions Test Temp. Compression Yield Temp. ('F) Time (hr) ( aF)tio: Tensile Yield As Produced Room 0,75 650 10 Room 0.79 50 Room 0.88 100 Room 0,92 700 10 Room 0.99 50 Room 1.00 100 Room 0, 96 800 10 Room 1. 12 50 Room 1. 14 100 Room 1. 13 As Produced 650 0.64 650 10 650 0.64 100 650 0.68 As Produced 700 0.61 700 10 700 0.85 100 700 0.92 As Produced 800 0.66 800 10 800 0.88 100 800 0.75 This behavior suggests that relief of residual stresses probably occurred during the unstressed exposures. WADC TR 57-150 Pt III 20

The effects of the unstressed exposures were completely eliminated by the application of tensile creep at either 650~ or 700~F. As both Figure 39 and 40 show, increased amounts of tensile creep at 650~ or 700~F tend to raise the subsequent tensile yield strength and lower the subsequent compression yield strength. Approximately 1 percent creep deformation was sufficient in most cases to restore the compression yield/tension yield ratio to that exhibited by the unexposed material. The yield strengths of material subjected to creep at 8000F tended to become equal after about 1 percent creep deformation and thereafter were little affected by further creep. It is evident that the application of tensile creep to this material caused a decrease in the compression yield strength relative to the tension yield strength for all the conditions investigated. Such behavior appears to be quite consistent with the definition of the Bauschinger effect quoted previously. Recovery effects also appear to operate at 800~F, but the general effect is the same for all temperatures of creep-exposure. It should be realized, of course, that the foregoing test results and discussion apply to material tested in the direction parallel to the sheet rolling direction. The directionality of the effect was further studied by tests on specimens taken transverse to the sheet rolling direction. These additional tests consisted of room temperature tension and compression tests of asproduced material or material exposed at 8000F for 100 hours without stress. The material tested was from Heats A5036 and A1172600. The samples from Heat A 1172600 were taken from a fourth sheet of test stock in order that the longitudinal and transverse specimens could be taken from adjacent portions of the sheet. The longitudinal properties of sheet 4 show good agreement with the average properties determined from sheets 1 - 3. The test results are summarized on page 22 and presented in the form of a bar graph in Figure 41. These data indicate that the transverse strengths of C 1 1OM tend to be about the same as or somewhat higher than the corresponding longitudinal properties. The compression yield/tensile yield ratio underwent no significant change in either heat as the result of unstressed exposure, and the transverse properties were "normal" for heat Al172600, although there appears to be a tendency for the transverse compression yield strength to be somewhat higher relative to the tension yield strength than was the case for the longitudinal value. The ratio of tensile yield to ultimate tensile strength appeared to be normal for all conditions of transverse testing. The Bauschingertype effect, therefore, does not appear to be present in the transverse direction of heat A1172600. The available evidence points very strongly to the presence of residual tensile stress in the longitudinal direction of the material. Such stress probably resulted from a straightening operation and, as indicated previously on page 20, should be removable by stress relief treatments. The effect of creep-exposure on the subsequent mechanical properties of transverse specimenswas not determined. The data for longitudinal tests, Figures 39 and 40, indicated that tensile creep caused changes in mechanical properties consistent with the definition of the Bauschinger effect (see page 21) and it is not unlikely that similar behavior would be encountered in the transverse direction. WADC TR 57-150 Pt III 21

Longitudinal and Transverse Tensile and Compression Properties of C1IOM at Room Temperature Test Direction* As -Produced Longitudinal Transverse Ult. Yield Ult. Yield Strength Strength Modulus, E Strength Strength Modulus, E Heat A1172600 (psi) (psi) (106 psi) (psi) (psi) (106psi) Tensile 147,000 141,000 15.5 145,500 131,000 16.0 143,500 139,500 15.3 149,000 134,000 15.8 Avg.(Sheet 4) 145,250 140,250 15.4 147,250 132,500 15.9 Avg. (Sheets 1,2, (146,211) (142,889) (16.5) 3) Compression 107,000 16.0 153,000 16.9 112,000 16.3 162,000 16.3 Avg. (Sheets 1,2,3) 109,500 16.2 157,500 16.6 (108,000) (16.2) Heat A5036 Tensile 130,000 113,000 14.4 128,500 124,000 15.7 136,000 116,000 15. 1 133,000 128,500 15.8 Avg. 133,000 114,500 14.8 130,750 126,250 15.8 Compression 116,500 16. 1 147,000 16.5 119,500 15.7 142,000 16.6 Avg. 118,000 15.9 144,500 16.6 Exposed 100 hours at 800~F Heat A1172600 Tensile 147,000 130,000 15.4 151,000 137,500 16.0 145,500 127,000 15.2 153,000 139,000 16.6 Avg. 146,250 128,500 15.3 152,000 138,250 16.3 Compression 135,000 135,000 17.3 157,500 15.8 137,000 16.7 155,000 16.7 Avg. 136,000 17.0 156,250 16.2 Heat A5036 Tensile 120,000 101,000 15.2 141,000 120,000 16.0 139,000 122,000 17.6 Avg. (120,000) (101,000) (15.2) 140,000 121,000 16.6 Compression 110,000 116.6 130,000 17.8 Avg. (110,000) (15.7) 130,500 17.2 * with respect to sheet rolling direction WADC TR 57-150 Pt III 22

METALLOGRAPHIC EXAMINATION Metallographic examination was made of several representative specimens of C 110M following creep-exposure. Photomicrographs of these specimens are presented together with a photomicrograph of the as-produced material in Figures 42-45, Included with the photomicrographs are the room temperature tensile and compression strengths following the specified exposure. The as-produced structure consisted of alpha grains in a beta matrix (Figure 42). Very little change at 1000X magnification was discernable in the microstructures of the material after creep-exposure. Figure 45 indicates a possible slight tendency for the alpha grains to become equi-axed during exposure at 800~F. The mechanical-property data included with these figures indicate that increases in strength or significant changes in interrelation between the tensile and compression yield strength occurred without any microstructural change visible using light microscopic techniques at 1000X. In earlier work conducted at the University on another heat of this alloy (Ref. 3) examination was made of as-received or heat-treated structures that had been creep tested for as much as 1000 hours at 600~F. This previous examination also indicated no change visible at magnifications up to 1000X. WADC TR 57-150 Pt III 23

DISCUSSION The results of this investigation indicate that prior creep-exposure had relatively little effect on the fracture strength or ductility of C1 10M in the longitudinal direction to rolling in either normal strain rate tensile tests or tension-impact tests. Exposure of the material either to temperature alone or to temperature and stress did cause significant changes in the manner by which it underwent plastic deformation in short-time tension or compression tests, The behavior can be attributed to the susceptibility of the material to a Baushinger-type effect and was manifested by an abnormally high tensile yield strength and a low compression yield strength in the asreceived stock. It was found that the effect could be modified or eliminated by exposure to temperature alone (in the manner of a stress relief treatment) or could be re-introduced by the application of plastic strain in tension. The plastic strain was composed of creep deformation and, depending on the temperature and stress level, short-time plastic strain obtained during loading. The maximum effects found followed creep-exposure at 700~F. The study of effects resulting from creep-exposure at 650~F was limited because of the small range of creep deformation that accompanied total deformations of up to 3 percent. Increases in tensile and yield strength following creep at 700~F were as much as 10-20 percent above the base strengths. Exposure to temperature alone at 8000F caused a decrease in the tensile yield strength of as much as 25 percent. This decrease was not eliminated by the introduction of stress to the exposure conditions. Fragmentary data indicate that exposure at 800~F for times up to 1000 hours might cause the room temperature yield strength to drop as much as 50 percent. The compression yield strength was generally found to be increased above the strength of the as-produced material by exposure to temperature alone. The increase in strength was lost when the material was subjected to tension creep. Generally, creep did not cause the yield strength to drop below the original value for the as-produced material. As the exposure time was increased, a larger amount of deformation was required in order to result in the same loss of compression yield strength. Very little could be interpreted from the results of the tension-impact tests, Excessive scatter masked what may have been a slight tendency for the strength to decrease following larger amounts of prior deformation. The tension-impact tests at elevated temperature showed little or no effect of prior creep on subsequent properties. The test data were studied in an attempt to determine the main factor affecting properties. Correlations were presented in terms of either creep deformation or total deformation versus mechanical properties following exposure. In the circumstance where creep represented the major part of the deformation, i. e., creep-exposures at 800F, the creep deformation can be safely said to be the governing factor. At 650F and in some cases at 700F, a substantial amount of plastic deformation occurred during loading. Under these WADC TR 57-150 Pt III 24

circumstances it is difficult to ascertain whether plastic loading deformation, creep deformation, or total plastic strain was the principal contributor to changes in properties. The effect of varying the proportions of loading deformation to creep deformation was studied by comparing the mechanical properties following constant amounts of total deformation, independent of the time required to reach them. Thus, three different loads, representing three different loading deformations, were required to reach a given total deformation in 10, 50, or 100 hours. Such an analysis was complicated by the effects due to exposure to temperature alone and, consequently, no clear cause could be fixed to explain the results of 6500 or 700~F creep-exposures on the basis of the presently available data. To explain these effects completely would require additional experimentation designed to separate the effects of short-time plastic strain, creep deformation, aging, and recovery effects. Such exposures should be directed to reach a specified final amount of plastic strain through a number of different paths involving combinations of pre-strain or post-strain, A limited number of room temperature tensile and compression tests on transverse samples indicated that the Bauschinger-type effect was not present in the transverse direction of the as-produced material. No information was obtained on the effects of creep-exposure on transverse specimens. It does appear to be fairly well established that exposure of C1 1M to plastic strain and/or temperature can cause marked changes in certain short-time mechanical properties of interest to the designer of aircraft structure. The alterations in the absolute values of tension and compression yield strengths and their ratio would certainly be an example of how service conditions could affect subsequent load-carrying ability. WADC TR 57-150 Pt III 25

CONCLUSIONS Exposure of C10OM sheet to temperature and stresses resulting in total deformations of up to 3 percent in 100 hours at temperatures of 650~, 700~, or 800'F caused little change in the fracture strength or ductility in tensile tests or tension-impact tests at either room temperature or the temperature of exposure. The as-received material exhibited an abnormally high tensile yield strength and a low compression yield strength in the directional longitudinal to the sheet rolling direction. Exposure to temperature alone caused a decrease in the tensile yield strength and an increase in the compression yield strength. These changes were dependent on the exposure time and temperature and the test temperature. Plastic deformation occurring during loading in tension, or mainly as a result of creep in tension, caused increases in the tensile yield strength and decreases in the compression yield strength. Again, these changes were dependent on both the exposure conditions and the test temperature. The behavior of the tension and compression yield strengths may be attributed to a Bauschinger-type effect. WADC TR 57-150 Pt III 26

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, Jeremy V., Voorhees, Howard R., and Freeman, James W., "Effect of Prior Creep on Mechanical Properties of Aircraft Structural Metals - Part II: 17-7PH (TH 1050 Condition)", WADC Technical Report 57-150, November 1957, 3. Gluck, Jeremy V., and Freeman, James W., "A Study of Creep of Titanium and Two of Its Alloys," WADC Technical Report 54-54, March 1956. 4. Hyler, W. S., "An Evaluation of Compression-Testing Techniques for Determining Elevated Temperature Properties of Titanium Sheet, " Titanium Metallurgical Laboratory, Battelle Memorial Institute, TML Report No. 43, pages 21, A-13 (June 8, 1956). 5. Templin, R. L. and Sturm, R. G., "Some Stress-Strain Studies of Metals," Journal of the Aeronautical Sciences, p. 189, (March 1940), 6. Lyman, T. (editor) Metals Handbook p. 2, published by American Society for Metals, Cleveland, Ohio (1948), WADC TR 57-150 Pt III 27

TABLE L TOTAL DEFORMATION DATA AND RETAINED TENSILE PROPERTIES > 0~tj~~~~~~ ~~~AT ROOM TEMPERATURE FOR C11OM H Subsequent Room Temperature Tensile Properties Loading Time to Reach Indicated Total Total Ult. Tensile 0.2%0 Offset U_ Test Temp Stress Deformation Deformation (hrs) Test Time Deformation Strength Yield Strength Elongation Reduction of Modulus, E Hardness ~_1 ('F) Spec. No. (psi) (%) 0.5% 1.0% Z. 0% 3.0% (hrs) (%) (psi) (psi) (%/2 inches) Area (%) 10 (psi) (R"C") 650 1C-32T 105,000 3.88 -- -- -- -- 43.3 5.49 166,000 147,000 10.0 30.0 15.8 33.6 Ul O 1C-36T 100,000 2.24 -- -- -- 0.03 91 5.95 173,000 169,000 11.5 13.7 15.1 40.4 ^t 2C-31C 97,000 1.60 -- -- 41 134* 165.9 3.45* 162,000 162,000 7.3 -- 15.4 36.1 _.H 3A-28T 95,000 0.84 -- 13.5 125.5 -- 166 2.63 165,000 160,000 12. 2 23.9 15.9 39,0 IA-36T 85,000 0.68 -- 110 -- -- 142 1, 10 144,000 141,500 20.0 32.6 15.0 38.4 2A-32T 75,000 0.60 -- 125 -- -- 142 1.05 164,000 159,000 14.5 22,8 16.8 3C-5T 70,000 0,56 -- 290 -- -- 307 1.03 151,000 145,000 19.7 27.9 15.4 IA-5T 60,000 0.48 5 -- -- -- 216 0.68 152,000 145,000 19.3 29.8 15.6 2A-IT 55,000 0.42 66.5 -- -- -- 142 0,53 146,000 140,000 15.8 31.2 15.8 36.1 PV 700 3C-24T 90,000 0.86 -- 0,4 12.9 25* 51 5.0* -- -- -- -- 00 3AB-17T 80,000 0,65 -- 22.2 47* 68* 71 3. 1* 164,000 158,000 13.0 22.0 15.2 39.2 2A-13T 75,000 0.63 -- 17 46 64 147 6,0* 174,200 164,800 7.3 17.3 16.5 2C-32T 65,000 0.52 -- 41 94 127 143 3.49 170,000 151,000 16.8 26.0 16.1 3A-5T 60,000 0,43 5 49 102 142 210 4.8* 169,000 149,000 16.5 21.2 16.1 1C-5T 50,000 0.36 28 108 220 -- 242 2.18 167,000 151,000 15.7 25.6 16.9 2C-9T 40,000 0.30 63 193 -- -- 193 1.10 158,000 140,000 17.5 27.0 16.6 IA-IT 35,000 0.21 110 -- -- -- 139 0.58 149,000 134,000 18.0 27.4 15.5 800 3C-13T 35,000 0.30 1 3.2 7.6 12.2 46 6.60 151,000 140,000 19.3 25.2 15.9 2A-20T 30,000 0.24 3 8.5 17.5 26 117 10* 151,000 138,000 20.3 28.6 15.0 - IA-24T 25,000 0.18 4 11 27.5 46.5 123 6.40 158,000 137,000 24.0 31.4 17.2 3C-32T 20,000 0. 18 11 29 87 160 169 3. 10 145,000 130,000 19.8 21.4 16.2 3A-32T 15,000 0.07 20 64 314 -- 358 2.11 143,000 125,000 23.0 25.2 15.2 33.2 2C-IT 10,000 0.09 52.5 296 -- -- 307 1.02 150,000 132,000 30.0 25.5 16.5 IC-20T 5,000 0.05 1140 -- -- -- 1292 0,52 135,000 67,700 23.8 33.5 16.3 35.9 * Estimate by extrapolation.

TABLE 2 TENSILE TEST DATA FOR CIOM AS PRODUCED 0. 2% offset Test Ult. Tensile Yield Strength Elongation Reduction of Modulus, E Temp (eF) Spec. No. Strength (psi) (psi) (%/ 2 inches) Area (%) 106 (psi) room 1A-9T 145,000 140,000 22. 0 35.2 16.8 1AB-17T 144,000 139,000 24.0 32.4 16.0 IC-13T 152,000 144,000 21 5 30,2 16.8 Average 147,000 141,000 23.5 32.6 16.5 2C-5T 146,000 144,000 22.3 29.6 16.8 2C-20T 147,000 143,000 21.7 31.6 16.4 2A-28T 146,000 142,000 20.5 32.0 16.9 Average 146,333 143,000 21.5 31.1 16.7 3C-20T 146,000 142,000 22.7 26.4 15.8 3A-13T 147,000 145,000 21.5 30.8 16.4 3A-34T 151,000 147,000 22.5 33.3 16.6 Average 148,000 144,667 22.2 30.1 16.3 Average - 9 tests 146,211 142,889 22.4 31,3 16.5 650 1C-24T 108,000 92,000 19.5 28.0 13.4 1A-32T 109,000 95,000 21.0 33.3 13.8 1C-9T 107,000 -- 15.1 31.6 13.6 Average 108,000 93,500 18.5 31.0 13.5 2A-24T 112,000 97,000 14.5 29.0 13.6 2C-13T 111,000 97,000 17.5 24.7 13.5 2A-5T 112,000 94,500 16.0 24.0 13. 9 Average 111,667 96,167 16.0 25.9 13.7 3C-9T 114,000 100,000 17.0 2 1.6 13.8 3C-34T 111,000 96,700 17.7 26.6 13.0 3A-1T 112,000 98,600 16.7 24.8 13.6 Average 112,333 98,433 17.1 24.3 13.5 Average - 9 tests 110,667 96,033 17.2 27. 1 13.6 700 IC-IT 94,900 83,500 17.2 36.4 12.3 1A-13T 106,000 91,000 19,0 34.1 13.7 1A-28T 105,000 92,700 21.2 31.4 13.6 Average 101,967 89,067 19.1 33.9 13.2 2C-36T 107,000 95,700 16. 1 32.7 13.6 2C-24T 107,000 91,400 17.0 32.8 13.3 2AB-17T 106,000 91,500 15.8 29.6 13.5 Average 106,667 92,867 16.3 31.8 13.5 3C-17T 107,000 97,500 16.0 32.4 12.8 3A-24T 109,000 96,700 18.7 2.2 13.4 3A-9T 108,000 94,000 19.0 28.0 12.7 Average 108,000 96,067 17.9 29.9 13. 0 Average - 9 tests 105,545 92,667 17.8 31.9 13.2 600 1C-28T 90,000 83,000 39.7 51.0 11.8 IC-17T 90,000 85,000 25.4 47.3 11.8 IA-20T 90,600 82,000 29.0 49.5 12.0 Average 90,200 83,333 31.4 49.3 11.9 2A-9T 91,000 79,700 30.0 48.7 12.0 2A-36T 93,000 84,500 46.5 51.0 12 3 2C-28T 93,200 85,500 32.0 49.7 11. 3 Average 92,400 83,233 36,2 49, 8 11.9 3C-1T 95,000 84,800 24,7 45, 3 11.2 3C-28T 95,300 85,700 30,8 47.2 11.1 3A-20T 94,000 87,000 21.3 43.4 11.2 Average 94,766 85,833 25.6 45.3 11.2 Average - 9 tests 92,455 84,133 31,1 48, 1 11.7 WADC TR 57-150 Pt III 29

TABLE 3 COMPRESSION TEST DATA FOR CIIOM AS PRODUCED 0, 2% offset Compression Test Yield Strength Modulus, E Temp ('F) Spec. No. (psi) 10~ (psi) room IC-24C 108,000 15.8 lA-SC 107,000 16.2 IA-13C 108,000 16.0 Average 107,667 16.0 2C-24C 107,000 16.7 2C-9C 109,000 15.9 2A-28C 105,000 16.4 Average 107,000 16.3 3A-24C 108,000 16.0 3C-32C 110,000 16.4 3A-9C 111,000 16.1 Average 109,667 16.2 Average - 9 tests 108,111 16.2 650 IA-24C 63,000 12.9 IC-32C 58,400 12.6 1C-5C 57,600 12.8 Average 59,667 12. 8 2C-28C 58,400 12.9 2A-9C 55,800 13.2 2A-5C 68,400 13.2 Average 60,800 13.1 3A-13C 58,600 13.2 3C-24C 71,000 13.3 3C-5C 57,800 12. 8 Average 62,400 13. 1 Average - 9 tests 61,000 13.0 700 IA-28C 57,900 12.7 1C-13C 53,800 12.5 IA-9C 55,400 12.3 Average 55,700 12.5 2C-13C 60,600 12.9 2A-24C -- 12.5 2C-5C 59,400 12.5 Average 60,000 12. 6 3A-32C 54,600 12. 7 3C-28C 59,000 12 5 3C-6C -- 12.4 Average 56,800 12.5 Average - 7 tests 57,243 12.5 800 IC-28C 53,900 11.8 IC-9C 55,100 11.8 IA-32C 53,800 11. 6 Average 54,300 11.7 2C-32C 62,500 12.0 2A-32C 55,400 11.7 2A-13C 55,600 11.9 Average 57,800 11.9 3A-28C 59,800 12 1 3C-13C -- - 3A-5C 54,600 11.7 Average 57,200 11.9 Average - 8 teats 56,337 11.8 WADC TR 57-150 Pt III 30

TABLE 4 TENSION-IMPACT TEST DATA (SMOOTH BAR) FOR AS-PRODUCED CIIOM Tension -Impact Test Temp Strength (*F) Spec. No. (ft-lb) room IA-SM 48 IA-13M 50 1C-24M 69 Average 55.6 2A-28M 67 2C-5M2 64 2C-9M 37 Average 56.0 3A-9M 50 3A-29M 62 3C-28M 58 Average 56.6 Average - 9 tests 56 650 IA-24M 47 IC-5MI 50 IC-13M 50 Average 49 2A-5M2 47 2A-9M 59* 2C-24M 44 Average 46 3A-5M1 45 3C-5M2 44 3C-9M 43 Average 44 Average - 8 tests 46 700 IA-5M2 53* IA-28M 48 IC-9M 47 Average 48 2AB-24M 43 2C-5M1 41 2C-13M 45 Average 43 3A-5M2 33* 3A-13M 43 3C-24M 43 Average 43 Average - 7 tests 44 800 IC-5M2 57* IC-28M 41 Average 2A-5MI 41 2A-13M 47 2C-28M 45 Average 44 3A-28M 45 3C-5M1 52* 3C-13M 41 Average 43 Average - 6 tests 43 * Omitted from Average. WADC TR 57-150 Pt III 31

H-^~~~~~ ~~~TABLE 5 EFFECT OF UNSTRESSED EXPOSURE ON ROOM TEMPERATURE Un 7 TENSILE PROPERTIES OF C 1 OM o n-~*t~~~~~~~~~~ ______________Tensile Properties After Exposure,_, Exposure Conditions Ult. Tensile 0.2% Offset' Temp Time Test Temp Strength Yield Strength Elongation Reduction of Modulus, E Hardness (*F) (hrs) Spec. No. (*F) (psi) (psi) (%) Area (%) 106 (psi) (R"C") 650 10.0 2A-31A room 144,000 136,000 25.3 31.4 15.1 35.3 50.0 1C-26C room 147,500 140,000 23.3 35.6 15.4 37.Z 100.0 ZA-21A room 143,400 136,800 24.0 32.2 15.5 35.8 105.5 IA-B26 room 145,000 135,000 20,5 34.8 15.0 36.5 Average 144,200 135,900 22.2 33,5 15.2 36.2 700 10.0 IC-D15 room 143,000 140,000 23.8 34.0 15.4 39. 1 10.0 3C-D33 room 146,000 --- 24.0 27.9 15.4 38.7 Average 144,500 140,000 23.9 30.9 15.4 38.9 50.0 2C-21C room 149,000 137,500 23.0 33.2 16 1 35.8 100.0 IA-3A room 146,500 140,000 19.5 32.0 15.4 38.5 800 10.0 1A-15A room 146,000 133,000 24.0 35.7 15.1 35.1 50.0 1C-D3 room 144,000 129,000 23.3 31.8 15.0 34.9 50.0 3C-33C room 146,000 130,000 22.5 29.8 15.8 36.3 Average 145,000 129,500 22.9 30.8 15.4 35.6 100.0 ZC-D31 room 147,000 125,000 19.3 29.2 15.7 34 1 _ _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

TABLE 6 EFFECT OF UNSTRESSED EXPOSURE ON ELEVATED TEMPERATURE 0 H3 TENSILE PROPERTIES OF C110M U,4 ~I _____________________Tensile Properties After Exposure i, 1 Exposure Conditions Ult. Tensile 0. 2% Offset o Temp Time Test Temp Strength Yield Strength Elongation Reduction of Modulus, E Hardness O (*F) (hrs) Spec. No. (*F) (psi) (psi) (%) Area (%) 100 (psi) (R"C"*), 650 10.0 3C-11C 650 112,700 94,900 20.5 26.0 13.7 35.4 50.0 2A-B21 650 111,500 94,500 17.5 27.6 12.9 34.5 100.0 2A-B7 650 114,000 97,000 22.5 26.3 12.9 35.8 105.5 3C-D11 650 109,000 97,500 15.0 26.4 13.1 37.2 Average 111,500 97,250 18.8 26.4 13.0 36.5 -....., _. _ _ L 700 10.0 2C-D7 700 107,000 91,000 17.5 31.6 13.5 36.5 50.0 3A-11A 700 108,000 90,000 13.8 16.9 13.1 35.5 100.0 3C-18C 700 109,000 84,400 17.3 30. 2 11.5 35.8 100.0 IC-D26 700 104,000 79,800 22.0 33.6 12.2 37.2 Average 106,500 82,100 19.7 31.9 11.8 36.5 800 10.0 3A-B33 800 91,600 74,400 22.3 48.6 11.3 34.7 10.0 IC-15C 800 87,400 67,300 33.0 49.0 11.5 36.0 Average 89,500 70,850 27.2 48.8 11.4 35.4 50.0 2A-B31 800 92,200 68,000 23.5 45.0 11.4 32.8 100.0 3A-18A 800 96,500 78,200 29.5 43.4 11.2 37.0 * Rockwell "C" hardness at room temperature

TABLE 7 H-J EFFECT OF PRIOR CREEP-EXPOSURE ON ROOM TEMPERATURE lid TENSILE PROPERTIES AND HARDNESS OF C110M UNominal Room Temperature Tensile Properties After Exposure (J1 Exposure Conditions Actual Exposure Conditions Ult Tensile 0.2% Offset o Temp Time Total Def. Time Temp Stress Load. Def. Load. Def. Creep Def. Total Def. Strength Yield Strength Elongation Reduction of Modulus Hardness It ('F)_ (_ hrs) (%) Spec. No. (hrs) ('F) (psi) (Total) (0%) (Plastic) (%) (%) (%) (psi) (psi) (%/2 inches) Area (%) E x 106(psi) R"C" 650 10 0.5 2CD3 10.0 650 59,000 0.42 nil 0.06 0.48 145,500 141,000 21.0 29.4 15.9 36.6 1.0 1ABI11 10.0 650 95,200 1.61 0.90 0.22 1.83 145,000 145,000 20.5 31.4 16.2 36.1 1-_ 3AB20 10.0 650 96, 60.5 0.94 0.24 0. 18 1. 12 144,500 141,500 22.3 33.4 15.0 37.3 2.0 3A29 10.0 650 97,500 1.30 0.60 0.30 1.60 148,000 148,000 20.0 27.5 15.7 36.8 3.0 1A17A 10.0 650 98,000 2.51 1.80 0.35 2.86 148,000 148,000 22,3 31.7 15.5 38.5 50 0.5 3CD8 50.0 650 56,000 0.32 nil 0.08 0.40 147,000 144,000 19.5 32.0 16.9 37.9 1.0 1C4 50.0 650 86,000 0.89 0.28 0.19 1.08 141,000 139,000 22.5 33.2 14.9 36.8 2.0 2AB26 50.3 650 96,800 1.49 0.76 0.55 2.04 151,000 148,000 24.3 30.2 16.0 37.2 3.0 2C15C 50.0 650 97,300 1.74 1.01 0.60 2.34 148,000 148,000 -- 25,7 15.7 38.4 100 0.5 1A30 100.0 650 54,000 0.41 nil 0.10 0.51 145,000 130,500 22.0 32.0 15.0 37.0 1.0 3A8 100.0 650 82,000 0.74 0. 14 0.26 1.00 151,000 147,000 21.0 28.3 15.4 37.5 2.0 2C3 100.0 650 95,200 0.80 0.10 0.47 1.27 152,000 148,000 18.8 28.2 16.0 37.9 3.0 2AB20 100.0 650 95,800 1.48 0.80 0.84 2.32 148,000 145,000 18.3 30,5 15.4 37.6 700 10 0.5 1A4 10.0 700 56,000 0.43 nil 0.12 0.55 138,000 135,000 21.0 30.0 14.7 38.5 1.0 3AB8 10.0 700 79,000 0.62 0.10 0.17 0.79 149,000 144,000 23.2 31.4 15.5 36.6 2.0 2A16 10.0 700 93,000 1.77 1.07 0.96 2.73 150,500 149,500 21.0 31.2 15.,2 37.9 3.0 3CD14 10.0 700 100,000 3.76 3.00 5.44 8.80 177,000 175,000 7.8 18.2 15.6 34.2 50 0.5 1CD30 50. 1 700 43,000 0.34 nil 0.21 0.55 146,000 141,000 22.0 32.1 17.0 37.7 1.0 3AB14 50.0 700 62,000 0.46 nil 0.38 0.84 152,000 145,000 20.5 28.8 15.7 37.5 2.0 2A26 50.3 700 75,000 0.64 nil 0.98 1.62 149,000 144,000 17.8 23.4 15.2 37.3 3.0 lA11 50.2 700 82,000 0.68 0.05 2.19 2.87 164,000 158,000 17.0 27.5 15.0 40.4 100 0.5 3A33A 100.0 700 36,000 0.25 nil 0.26 0.51 148,000 136,500 20.5 28.8 16.5 38.0 1.0 2A7A 100.1 700 51,000 0.36 nil 0.32 0.68 149,000 138,000 21.7 32.9 15.2 34.7 2.0 1A26A 100.0 700 63,000 0.50 nil 1.78 2.28 162,000 149,000 17.3 26.2 16.1 39.4 3.0 3AB11 117.7 700 69,000 0.51 nil 1.89 2.40 162,000 152,000 15.0 23.8 15.2 38.3 800 10 0.5 1CD11 10.0 800 21,000 0.18 nil 0.33 0.51 144,000 134,000 22.5 33.2 15.2 36.0 1.0 2AB2 10.0 800 28,000 0.21 nil 0.58 0.79 141,400 132,300 25.0 31.4 16.2 35.8 2.0 2CD16 10.0 800 34,000 0.29 nil 1.76 2.05 147,000 135,000 20.5 30.6 15.3 35.8 3.0 1AB4 10.0 800 37,000 0.29 nil 2.08 2.37 146,000 137,500 22.7 30.8 15.5 37.2 50 0.5 2CD21 50.0 800 11,000 0.08 nil 0.40 0.48 142,000 125,000 23.5 31.1 16.0 36.7 1.0 1CD4 50.0 800 17,000 0.14 nil 0.92 1.06 143,500 128,000 21.0 31.4 15.4 36,7 2.0 3CD18 50. 1 800 22,500 0.16 nil 2.16 2.32 149,000 130,500 20.0 25.5 158 35. 1 3.0 IAB15 50.0 800 25,000 0.20 nil 2. -I 2.64 146,000 131,000 21.3 30.3 15.7 36.1 100 0.5 IAB3 100.0 800 9,500 0.11 0.03 0.45 0.56 142,000 121,000 22.3 30.3 15.9 33.7 1.0 3AB18 100.0 800 14,000 0.13 0.03 1. 11 1.24 145,000 129,000 21.8 29.6 16.1 36.5 2.0 2C7C 100.1 800 19,500 0.17 0.02 2.04 2.21 146,000 130,000 20.5 25.8 16.5 31.3 3.0 1C3C 100.0 800 22,000 0. 17 nil 2.67 2.84 145,000 19.5 28.7 16.3 33,1

Ul C3 n TABLE 8 OU- EFFECT OF PRIOR CREEP-EXPOSURE ON ELEVATED TEMPERATURE 0 It TBETENSILE PROPERTIES OF C 10 M Nominal Tensile Properties After Exposure P' Exposure Conditions Actual Exposure Conditions Test Ult.Tensile 0.2% Offset Temp Time Total Def. Time Temp Stress Load. Def. Load, Def. Creep Def. Total Def. Temp. Strength Yield Strength Elongation Reduction of Modulus,E Hardness (*F) (hrs) (%) Spec. No. (hrs) ('F) (psi) (Total) (%) (Plastic) (%) (%) (%) F) (psi) (psi) (%/2 inches) Area (%) x 106 (psi) R"C"* 650 10 0.5 1CDI 10.1 650 59,000 0.43 nil 0.05 0.48 650 106,000 89,400 17.5 32.2 13.7 37.0 1.0 2A36A 10.1 650 95,200 1.86 1.15 0.27 2.13 650 109,000 98,800 14.5 30.9 13.6 37.8 100 0.5 3A15 100.1 650 54,000 0.37 nil 0.11 0.48 650 110,000 91,500 12.5 29.4 13.6 37.9 1.0 1C7 100.0 650 82,000 0.68 0. 12 0.24 0.92 650 107,000 88,500 17,7 30.5 12.8 37.5 2.0 2C25 100.0 650 95,200 1.62 0.94 0.69 2.31 650 115,000 102,000 11.3 34.5 13.6 36.8 3.0 3A21A 100.0 650 98,000 1.15 0.45 1.13 2.28 650 113,000 102,000 -- 33, 8 13,7 38.7 UO'1 700 10 0.5 3CD27 10.0 700 56,000 0.38 nil 0.10 0.48 700 107,000 -- 16,5 35.5 - 36.0 1.0 1AA36 10.0 700 82,000 0.69 0.05 0.25 0.94 700 103,000 93,000 17.3 33.6 12.5 37.8 2.0 2C17C 10.0 700 90,500 0.93 0.24 0.50 1.43 700 112,000 98,400 17.5 33.6 12.1 35.0 3.0 IABI 10.0 700 92,000 1.04 0.33 0.74 1.78 700 106,500 96,300 15.8 33.8 12.3 35.4 100 0.5 2CD25 100.0 700 36,000 0.36 0.24 0.41 0.67 700 112,500 82,000 15,5 33.2 12.0 37.5 1.0 1A7 100.0 700 51,000 0.34 nil 0.74 1.08 700 112,000 78,300 13.0 25.0 12,6 38.0 2.0 2C10 100.0 700 63,000 0.46 nil 1.09 1.55 700 119,500 93,600 14.3 32.9 12 8 38.7 3.0 3AB3 100.0 700 70,000 0.56 0.02 1.86 2.42 700 119,000 98,400 8.0 20.9 12.9 36.9 800 10 0.5 3A27 10.0 800 21,000 0.17 0.04 0.44 0.61 800 93,000 64,200 36,5 53.0 12.2 37.0 1.0 3C8 10.0 800 28,000 0.25 nil 0.77 1.02 800 93,100 70,100 25.0 36.0 11.5 34.2 2.0 IAB20 10.0 800 34,000 0.26 nil 1.23 1.49 800 90,700 78,200 38.5 36.6 12.8 36.6 3.0 2A17A 10.0 800 38,000 0.30 0.02 1.69 1.99 800 92,500 69,400 33.0 51.5 11.5 36.9 100 0.5 IAB33 100.0 800 9,500 0.08 nil 0.51 0.59 800 88,000 73, 400 29.3 49.3 12.8 36.4 1.0 3C15 100.3 800 14,000 0.11 nil 0.94 1.05 800 87,500 57,500 47.0 57.0 12.2 36.1 2.0 IAB7 100.0 800 19,500 0. 17 nil 1.91 2.08 800 87,000 56,700 43.8 50.8 12.7 36.8 3.0 2A25 100.0 800 22,000 0.15 nil 3.04 3.19 800 90,000 59,800 32.8 50.0 11.8 36.9 * Rockwell "C" hardness at room temperature

TABLE 9 EFFECT OF UNSTRESSED EXPOSURE ON ROOM TEMPERATURE COMPRESSION PROPERTIES OF C I 1OM Exposure Conditions Compression Properties After Exposure Exposure Exposure 0. zul Offset Compression Temp Time Test Temp Yield Strength Modulus, E ('F) (hrs) Spec. No. (F) (psi) 106 (psi) 650 10 1AB13 room 115,000 15.9 10 2C32 room 105,000 16.1 Average 110,000 16.0 50 2CD9 room 126,000 16.2 50 3CD13 room 124,000 16.5 Average 125,000 16.4 100 1AA28 room 128,000 15.9 100 3AB9 room 119,000 15.4 Average 123,500 15.6 700 10 1CD24 room 147,000 16. 1 10 3CD9 room 136,000 15.7 Average 141,500 15. 9 50 1AB24 room 127,000 15.6 50 3C32 room 152,000 16.6 Average 139,500 16. 1 100 2CD32 room 134,000 15.7 100 3AB 13 room 132,000 15.0 Average 133,000 15.4 800 10 1CC32 room 149,000 16.5 10 2CD24 room 151,000 16.3 Average 150,000 16.4 50 2AB9 room 147,000 16. 1 50 3CD24 room 153,000 16.2 Average 150,000 16.2 100 1AB32 room 135,000 16 6 100 3C28 room 142,000 16. 8 Average 138,500 16.7 WADC TR 57-150 Pt III 36

TABLE 10 EFFECT OF UNSTRESSED EXPOSURE ON ELEVATED TEMPERATURE COMPRESSION PROPERTIES OF C 110M Exposure Conditions Compression Properties After Exposure Exposure Exposure 0. 2% Offset Compression Temp Time Test Temp Yield Strength Modulus, E ('F) (hrs) Spec. No. ('F) (psi) 106 (psi) 650 10 lCD13 650 61,000 13.2 10 3AA32 650 58,400 13.2 Average 59,700 13.2 50 1CD32 650 59,100 13.7 50 2AB13 650 Average (59,100) (13.7) 100 2A24 650 63,700 13.6 100 3CD32 650 65,300 13.4 Average 64,500 13.5 700 10 2CD13 700 82,700 13.4 10 3A28 700 73,900 12.8 Average 83,300 13. 1 50 1CC28 700 67,800 12.7 50 2AA32 700 76,500 13. 1 Average 72,150 12.9 100 1AA32 700 62,000 12.5 2AA28 700 88,000 13.3 Average 75,000 12.9 800 10 2CC28 800 62,500 12.6 10 3AB24 800 63,800 11.2 Average 63,150 12.2 50 1AB9 800 67,800 11. 8 50 3AB32 800 72,500 12.5 Average 70, 150 12.2 100 1CD9 800 60,800 12.2 100 2AB32 800 58,800 11.8 Average 59,800 12.0 WADC TR 57-150 Pt III. 37

TABLE 11 EFFECT OF PRIOR CREEP-EXPOSURE ON ROOM TEMPERATUIRE COMPRESSION PROPERTIES OF C110M ~>Compression Properties Nominal After Exposure 0(' ___Exposure Conditions Actual Exposure Conditions Test 0. 2% Offset Compression H Temp Time Total Def. Time Temp Stress Load. Def. Load. Def. Creep Def. Total Def. Temp Yield Strength Modulus ('F) (hrs) (%) Spec. No. (hrs) (.F) (psi) (Total) (%) (Plastic) (%) (%) (%) (.F) (psi) E x 106 (psi) -1 650 10 0.5 3CD15 10.0 650 59,000 0.44 nil 0.05 0.49 room 115,000 15.8 1.0 2AB10 10.0 650 95,000 1.54 0.85 0.22 1.76 room 107,500 15.3 U 2.O0 IA18 10.0 650 97,520 2.66 1.95 0.55 3.21 room 98 300 15.2 O 3.0 3CD10 10.0 650 98,000 1.06 0.35 0.20 1.26 room 101,000 15.9 50 0,5 ICD18 50.0 650 56,000 0.44 0.03 0.07 0.51 room 118,000 15.2 K-~ 1.0 2AB25 50.0 650 88,929 0.72 0.06 0.27 0.99 room 114,000 16.9 2.0 3CD3 50.0 650 96,800 0.85 0.15 0.85 1.70 room 104,000 15.2 3.0 1AB29 50. 1 650 97,500 2.25 1.55 0.85 3. 10 room 108,000 16. 1 100 0.5 3C3 100.0 650 54,000 0.36 nil 0.08 0.44 room 127,000 16.7 1.0 1C18 100.0 650 82,000 0.72 0.13 0.38 1.10 room 114,000 15.7 2.0 2A10 101.0 650 95,200 2.24 1.53 0.86 3.10 room 108,000 15.3 3.0 1CD6 100.0 650 95,900 2.19 1.50 1.24 3.43 room 102,000 16.0 o 700 10 0.5 1CD33 10.0 700 56,000 0.43 nil 0. 11 0.54 room 125,000 16.4 00 1.0 2A2 10.0 700 82,000 0.62 nil 0.32 0.94 room 115,000 15.3 2.0 3C27 10.0 700 90,500 1.27 0.58 0.66 1.93 room 94,400 16.8 3.0 lAB18 10.0 700 92,000 2.16 1.45 1.43 3.59 room 103,000 16.6 50 0.5 2C2 50.6 700 43,000 0.33 nil 0. 19 0.52 room 130,000 15.0 1.0 1A33 50. 0 700 64,000 0.53 0.03 0.60 1. 13 room 120,000 16.3 2.0 3AB15 50.0 700 75,000 0.61 0.03 1.54 2. 15 room 106,500 16.0 3.0 2CD10 50.0 700 82,000 0.73 0.10 5.72 6.45 room 110,000 15.9 100 0.5 2CD26 100. 1 700 36,000 0.27 nil 0.31 0.58 room 136,000 16.4 1.0 3AB29 100.0 700 51,000 0.38 nil 0.67 1.05 room 131,000 16.2 2.0 3C14 99.9 700 63,000 0.51 0.02 0.84 1.35 room 121,000 16.2 3.0 1C30 100. 1 700 70,000 0.61 0.07 2.91 3.52 room 114,000 16. 1 800 10 0.5 3C29 10.0 800 21,000 0. 15 nil 0.42 0.57 room 131,000 16.3 1.0 2A3 10.0 800 28,000 0.22 nil 0.64 0.86 room 136,000 15.7 2. 0 3A 14 10.0 800 34,000 0.27 nil 1.44 1.71 room 136,000 16.5 3.0 2C26 10.0 800 38,000 0.32 nil 2.30 2.62 room 136,000 16.4 50 0.5 3A3 50.0 800 11,000 0.06 nil 0.32 0.38 room 140,000 15.6 1.0 1C33 50.0 800 17,000 0. 12 nil 0.97 1.09 room 129,000 16.8 2.0 2CD2 50.0 800 22,500 0.17 nil 1.71 1.88 room 123,500 16.5 3.,0 3AB27 50. 0 800 25,000 0.20 nil 2.78 2.98 room 129,000 16.2 100 0.5 2AB16 100.0 800 9,500 0.09 nil 0.44 0.53 room 132,500 15.5 1.0 3CD29 99.9 800 14,000 0. 10 nil 0.97 1.07 room 135,200 15.8 2.0 2C16 99.9 800 19,500 0. 14 nil 1.37 1.51 room 128,000 15.5 3.0 1AB30 100.0 800 22,000 0. 19 nil 2.87 3.06 room 130,000 15.2

TABLE 12 EFFECT OF PRIOR CREEP-EXPOSURE ON ELEVATED TEMPERATURE COMPRESSION PROPERTIES OF CllOM H Compression Properties..j Nominal After Exposure I Exposure Conditions Actual Exposure Conditions Test Compression Ul Temp Time Total Def. Time Temp Stress Load. Def. Load. Def. Creep Def. Total Def. Temp Yield Strength Modulus, E o (F) (hrs) (%) Spec. No. (hrs) ('F) (psi) (Total) (%) (Plastic) (%) (%) (%) (*F) (psi) 106 (psi) t 650 10 0.5 2CC4 10.0 650 59, 100 0.40 0.02 0.05 0.45 650 67,800 13.5 1.0 3CD21 10.0 650 95,100 0.79 0.08 0. 15 0.94 650 53,600 13.5 2.0 2C36C 10. 1 650 97,500 2. 16 1.45 0.26 2. -2 650 51,700 13.7 3AB30 10.0 650 97,500 1. 15 0.45 0. 17 1.32 650 49,600 14.7 100 0.5 3AB1 100.0 650 54,000 0.37 nil 0. 11 0.48 650 66,000 13.2 1.0 1C17C 100.0 650 82,000 0.70 0. 12 0.35 1.05 650 67,600 14. 1 2.0 3A34A 100.0 650 95,200 0.76 0.06 0.68 1.44 650 53,800 13.6 3.0 2AB27 100.0 650 96,000 1.13 0.4- 0.57 1.70 650 54,700 13.3 700 10 0.5 3C10C 10.0 700 56,000 0.39 nil 0.09 0.48 700 63,800 12.8 Wo 1.0 2A15A 10,0 700 82,000 0.70 0.06 0.29 0.99 700 56, 100 12.2 O1. 2,0 2CD4 10.0 700 90,500 0.88 0.20 0.46 1.34 700 58,700 13.2 3.0 1AA23 10.0 700 92,000 1.08 0.38 1.57 2.65 700 55,500 12.5 100 0.5 IC36C 100.0 700 36,000 0.27 nil 0.31 0.58 700 78,300 12.6 1.0 2AB1 100.0 700 51,000 0.37 nil 0.66 1.03 700 67,000 13.0 2.0 2CD20 100.0 700 63,500 0.43 nil 1.55 1.98 700 59,500 13.6 3.0 3A17A 100.0 700 70,000 0.51 nil 2.70 3.21 700 91,800 12.8 800 10 0.5 2CD15 10.0 800 21,000 0. 16 nil 0.45 0.61 800 64,800 11.8 1.0 3C21C 10.0 800 28,000 0.22 nil 0.57 0.79 800 70,100 11.6 2.0 1AA16 10.0 800 34,000 0.26 nil 1.35 1.61 800 67,300 12.5 3.0 1C31C 10.0 800 38,200 0.31 0.02 2.27 2.58 800 6-,600 12.4 100 0.5 2A27A 100.0 800 9,500 0.08 nil 0.51 0.59 800 71,000 11.8 1.0 1C14C 100.0 800 14,000 0.10 nil 0.99 1.09 800 6-, 600 11.7 2.0 3AB21 100.0 800 19,500 0. 15 nil 2. 19 2.34 800 69,000 12.3 3.0 2AB15 100.0 800 22,000 0.17 nil 3.05 3.22 800 64,600 11.9 2CD1 100.0 800 28,000 0. 19 nil 6.66 6.85 800 62,200 12.4

TABLE 13 EFFECT OF UNSTRESSED EXPOSURE ON ROOM TEMPERATURE TENSION-IMPACT PROPERTIES OF C11OM Tension-Impact Properties After Exposure Exposure Conditions Tension-Impact Temp Time Test Temp Strength Elongation Reduction of Area ("F) (hrs) Spec. No. (F) (ft-lb) (%/2 inches) (%) 650 10 1CD5 room 65 60 27. 7 10 2CD24 room 53 8,0 24.5 Average 59 7.0 26. 1 50 IA13A room 46 5.0 16.7 50 3CD24 room 52 7.5 22.4 Average 49 6.2 19.6 100 2A24 room 86 15.0 35. 3 100 3A5 room 50 6.0 36.7 Average 68 10.5 36.0 700 10 1CC32 room 95 15.5 29.6 50 2CC28 room 76 8.5 27.4 50 3AB9 room 44 5.0 17. 5 Average 60 6.8 22.4 100 1C13C room 53 4.0 21.0 100 2C32 room 57 11.0 28 3 Average 55 7.5 24.6 800 10 1CC28 room 64 10 5 37, 3 10 3AA32 room 66 13.0 27 8 Average 65 11.8 32.6 50 2AA28 room 69 6.0 26 5 50 3AB24 room 34 4.0 13.6 Average 52 5.0 20.0 100 2AA13 room 83 1 6.5 30 1 100 3A28 room 78 15.0 30,4 Average 80 15.8 30.2 WADC TR 57-150 Pt III 40

TABLE 14 EFFECT OF UNSTRESSED EXPOSURE ON ELEVATED TEMPERATURE TENSION-IMPACT PROPERTIES OF C11OM Tension-Impact Properties After Exposure Exposure Conditions Tension-Impact Temp Time Test Temp Strength Elongation Reduction of Area (F) (hrs) Spec. No. ('F) (ft-lb)_ (%/2 inches) (%) 650 10 2CD5 650 45 11.0 34. 5 10 3C32 650 46 12.0 29.3 Average 46 11.5 31.9 50 1CD24 650 49 13.5 37.7 50 2CD9 650 44 12.0 30.0 Average 46 12.8 33.8 100 IAB5 650 50 12.0 37.5 100 3CD9 650 42 10.0 36.0 Average 46 11.0 36.8 700 10 1AA28 700 47 13.0 41.2 10 2AB5 700 49 11.0 30.7 Average 48 12.0 36.0 50 1AB9 700 47 12.5 35.8 50 2AA32 700 46 12.0 32, 1 Average 46 12.2 34.0 100 2AB9 700 68 8.5 20.2 100 3C5 700 56 8.5 23.7 Average 62 8.5 22.0 800 10 1AA32 800 35 12.0 34.4 10 2CC13 800 44 12.5 28.6 Average 40 12.2 31.5 50 1AB24 800 46 13.5 35.5 50 3C13C 800 52 10.8 31.3 Average 49 12.2 33.4 100 ICD9 800 46 12.0 32.2 100 3A13 800 50 10.0 31.3 Average 48 11.0 31.8 WADC TR 57-150 Pt I!I 41

TABLE 15 (Q EFFECT OF PRIOR CREEP ON SMOOTH SPECIMEN TENSION-IMPACT PROPERTIES OF Cl10M H Il J1l Nominal Tension-Impact Properties After Exposure o Exposure Conditions Actual Exposure Conditions Tt Tensio Test Tension-Impact d Temp Time Total Def, Time Temp Stress Load Def. Load Def. Creep Def, Total Def, Temp Strength Elongation Reductionof, ('F) (hrs) (%) Spec. No. (hrs) ('F) (psi) (Total) (%) (Plastic )(%) (%) (%) ('F) (ft-lbs) (%/2 inches) Area (%) 650 100 0.5 1C6C 100.0 650 54,000 0.35 nil 0.08 0.43 room 27 2.5 300 1.0 3CD2 100.0 650 82,000 0.62 0.02 0.29 0.91 room 55 6.5 29.2 2.0 2C27C 100.0 650 95,200 1.41 0.74 0.86 2,27 room 82 10.5 23,9 3.0 1A31A 100.0 650 95,900 1.91 1.23 1. 14 3.05 room 41 5.0 270 1.0 2AB34 100.0 650 82,000 0,64' 0.04 0.24 0.88 650 46 12.0 35 0 3.0 1CD14 100.0 650 95,900 0,81 0, 13 0.99 1.00 650 50 11.5 32.6 700 10 0.5 1AB6 10.0 700 56,000 0.40 nil08 0.0848 room 62 9.5 18.2 1.0 2CD34 10.0 700 82,000 0.75 0. 11 0.50 1.25 room 49 5.5 16.0 2 0 3AB10 10,0 700 91,000 0,88 0. 18 0.38 1,26 room 79 14.0 35.3 3. 0 ICD31 10.0 700 92,000 1.00 0.30 0.53 1.53 room 70 10.0 40.3 0.5 3CC2 10.0 700 56,000 0.39 nil 0.07 0.46 700 -3 12.0 41 1 1.0 lAB 14 10.0 700 82,000 0.7'. 0.10 0.21 0.95 700 50 12.0 36,8 2.0 2CD27 10.0 700 90,800 0.86 0.09 0.59 1.45 700 -5 9.0 36.9 3.0 3A30A 10.0 700 92,000 0.78 0,07 0.50 1.28 700 -5 9.5 28.9 100 0,5 2AB4 100.0 700 36,000 0.25 nil 0.19 0.44 room 64 11.0 25.7 1.0 3C30C 100.0 700 51,000 0.342 nil 0.41 0,75 room 77 10.0 21,9 2.0 1AB31 100.0 700 63,000 0.42 nil 1.06 1.48 room 73 12.5 30 5 3.0 2CC34 100.0 700 70,000 0.54 nil 1.70 2.24 room 59 9.5 21.3 0.5 3AA2 100.0 700 36,000 0.25 nil 0.22 0.47 700 48 10.0 28 5 1.0 2AA4 100.0 700 51,000 0.39 nil 0.35 0.7i 700 47 12.0 34.2 2.0 1CD23 100.0 700 63,000 0.45 nil 1.64 2.09 700 45 6.0 26.7 3.0 3AA10 100.0 700 70,000 0.51 nil 2.33 2.84 700 4 7.5 23.8 800 100 0.5 2A34A 100.0 800 9,500 0.06 nil 0.43 0.49 room 61 10.0 31.3 1.0 3CD30 100.0 800 14,000 0. 10 nil 0.87 0.97 room 62 10.0 26.6 2.0 1AA14 100.0 800 19,500 0.15 nil 2,32 2.47 room 57 9.5 31.6 3.0 1CD20 100.0 800 21,000 0.15 nil 2.79 2.94 room 71 10.5 27.4 1.0 1C23C 100.0 800 14,000 0. 10 nil 0.89 0.99 800 41 10.0 40.0 3.0 3AB2 100.0 800 22,000 0.15 nil 2.85 3.00 800 39 11.0 30.9

TABLE 16 COMPARISONS OF ORIGINAL AND CHECK TEST TENSILE AND COMPRESSION DATA FOR TWO HEATS OF C 1 10M TITANIUM ALLOY Compression Test Temp. Yield Modulus (~F) Spec. No. Strength (psi) E x 106 Remarks Original Results - Heat A1172600 Room Average 108,111 16.2 Average Tensile Test Results Ultimate Strength - 146,211 psi Yield Strength - 142 889 psi Modulus - 16 5 x 10 psi Check Test Results - Heat A 1172600 Room 1A9A 103,000 15.0 Normal Support Force 2A24A 108,000 15.2 Normal Support Force 2C9C 104,000 15.7 Normal Support Force 3A24A 108,000 16.0 Normal Support Force 3C2C 1 1, 500 15.5 Support Force= 50 in-lb. Original Results - Heat A 1172600 700 Average 56,800 12, 5 Average Tensile Test Results Ultimate Strength - 105,545 psi Yield Strength - 92,667 psi Modulus - 13.2 x 106 psi Check Test Results - Heat A1172600 700 1C9C 54,800 13. 2 Support Force = 60 in-lb. 2C241C 58, 500 13. 0 Normal Support Force 3C9C 50,300 13.3 Normal Support Force Check Test Results - Heat A5036 Room Tensile Ultimate Yield Modulus 130,000 113,000 14.4 136,000 116,000 15. 1 Average 133,000 114,500 14.8 Compression Yield Modulus 116,500 16. 1 119,500 15.7 Average 118,000 15.9 Heat No. Test Temp. Ratio: Compression Yield/Tension Yield A1172600 Room0. 76 700' 0.61 A5036 Room 1.03 BoeingData Room 0,97-1.08 Data from TML Report No. 43 Armour Data Room 1.02-1. 09 Data from TML Report No. 43 700' 0.98-1.20 Data from TML Report No. 13 WADC TR 57-150 Pt III 43

a1~> ~ Section CD Section CC Section AB Section AA U Strip tl CD1 C1T AB1 A1T I, Q x y C2 A2' C C3 A3') 4) c1 A1'.c ^ r^g C5 I CLM21C5CI C5T CD20 AB|AM20 A C AL T k$1 o ___C88__________________________ 09 C9T r9M1 |C94 A9 I A9T A9 1 9 X C?1 2A ~d o C12 A12 cO A c26 A13 o I 13 I C13 1 A13T A14 ^ 5 _____________C16_______________________________A16: C15D C~~~ I c~~~~~~~~16A 0 o ^ CD17T CC17 B17T I AA1 0< 0___________________________________C22 A22 C23 A18 C2)1 ICI C2 I C2lT A2h AB20 M 2 A2T sUp2~:tr~~~~~~ >~~___ __C231 A21 C26 A26 J" __ ^ ___________0_______________ C27 A27' fJ28d C28MI C28T IC28 Id A28MI A28T A28 _n C29 A29 C30 A30 o, n C31 A31 0 t C3 1 - r Ic~n: C2J C32T 32d32 A]PM I A32T 32CA32 32 C33 A33 C34 A34 o CD6 I C35 A35 CDm6T CC36 AB36T I AA36 O

Exposure Spec. 0. 530 0. 003) Tensile Spec. 0. 500 3) i -15/1 4- 8 ^'5/1^ IR C) ____ ___________ _ -1 Grind last 1/32 each edge, 3 D — longitudinally 5/32 D 3/8 D 22 Tensile or Creep-Exposure Specimen ^.___________, - R 0.200 i ^ ^ (+~0. 003) - 1-1/4 — 3/4 —----- 2 -3 /4 1-1/4 ^_____________________________________ ___ 6 ______________________________ Tension-Impact Specimen DO NOT SCALE 0.500 ALL SPECIMENS ALL DIMENSIONS IN INCHES (+ 0. 003) FULL SHEET THICKNESS --— 2 —3/4 —---- - 2- 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).

-10 --- I — I' I I I I I I l- =- -- -- I I' I-I 0 0. S A 1.0 LPercent Total o 2 0 Deformation ~0~~~0 0 1 3. I, 80 4d14 7 0. 56% on load _ _ \-.0* - 650 F (eat) 0. 5% 5, a I J I I a I J I I I I J J I 1 I a O.1 1 10 50 100 1000 Time - hours o' t I' I' I I I'' \ 90 \ \o 70 0 52% on load 60 Code -1 _300%. \ \3 A1.0 Percent Total S ~2.01 Deformation 50 03 so \ - ~2.0% 40 1.0% 700F 30, I I o..5% 0. 1 1 10 50 100 1000 Time - hours WADCTR 57-150 Pet IIIG- 1' 46" 30 20. A.0L Percent Tn.'otal.'0% 02.O Deformation Time - hours 50 100 Figure 3, - Stress Versus Time to Reach Indicated Total Deformation for CIIOM at 650, 700' and BOO8F. WADC TR 57-150 Pt III 46

o g, 140 ol40o I \ ~N \ Ultimate *g 130 \ \ Tensile, 120 \ rt Tensile. 110 Yield U) 0 0 s 100 \ o o 90 ~ 80 \ Compression 80 Yield ~ \ 70 Points are average \ values of 9 tests 60 50 )_ 0 50 I I I I I I-.1 | ~ 0 100 200 300 400 500 600 700 800 900 v40 o Reduction of Area TO 30 0 2, 30 -_.',' <,, Elongation Mn ~10 C. a 0 I I I I I I I 0' f-+e 0 100 200 300 400 500 600 700 800 900 60 I U- O~ _ Tension-Impact Strength |NI 50, 0 4J r4 -5 -~,______ 5U] z^ 40 H 3 0 I I I I I I 30 O 100 200 300 400 500 600 700 800 900 Test Temperature - *F Figure 4. - Effect of Test Temperature on Short-Time Mechanical Properties of As-Produced C110OM (Heat A 1172600). WADC TR 57-150 Pt III 47

150 I - I — I I 0.2% Offset 140' Code Yield Strength A Room 130 B 650'F C 700F Test D 800 F Temperature 120 110 100 o 90 90 U) 80 I / / / 70 D 60 50 40 30 20 10 Strain - inches per inch Figure 5. - Tensile Test Stress-Strain Curves for As-Produced CL lOM WADC TR 57-150 Pt III 48

150 140 Code A Room B 650'F[ 130 C 760 - Test D 800 F- Temperature 120 110 0.2% Offset Yield Strength 100 - Or4 o 50 B 30 / o 90 <h- / 70 10 - 50 B' B Strain - inches per inch Figure 6. - Compression Test Stress-Strain Curves for As-Produced CLIOM, WADC TR 57-150 Pt III 49

C4 0 160 — 4 00 140 - Code an ou|w~ 0 650'F Exposure A 700'F Temperature 130 0 800F' O' Unexposed 120 t -,I I I I lI I I, - 140 O 130 120 800F i-d I 0 30 | t a) h' F 10 U'n, 32 0 - o 20 o 0 10 20 30 40. 50 60 70 80 90 100 Exposure Time - hours Figure 7, - Effect of Unstressed Exposure at 650*, 700-, or 800F on Room Temperature Tensile Properties of C1LOM. WADC TR 57-150 Pt III 50

o 120 o 0 - -- ___ 650'F rt. 1 1 0 ~',Cd I _ _ _ _ _ k o,~ 700F A,- 00 800'F c I oF h 10 0, 0 0 9__,__ O O _ 800.F rt & D 80 100 I SO,~~~~~ O 650 F ~,90 t Code = 700 F ~ E~ 0 650 F Exposure TemperatureA H~ 80 A 700'F- and 80 \ 800'F Test Temperature m O p^Y0,o Unexposed (/2 o - o_ "- 800F' 2o" 70 60 60.i -I I,.I I.I.I I I, I ~ I II I I I I I II 30 ] _. 800'F 0O o.,. 20O -0 —— ____ s 1 A 700*F 0Q 10 0 10 20 30 40 50 60 70 80 90 100 10 Exposure Time - hours Figure 8. - Effect of Unstressed Exposure at 650', 700', or 800'F on Elevated Temperature Tensile Properties of C11OM WADC TR 57-150 Pt III 51

C) H in 10 hr Prior Creep at 650F 50 hr Prior Creep at 650"F 100 hr Prior Creep at 650F -..J.c - j r^O --- — 16 I* — | -- -- I -- -- 160 160 Un~~~0 o I 15 0 / 0 fn [_,_ L * ~ - -~~~~~~~0 150 -* P' ^ -- 150 1..1 E:^~~~ "iO ~ o -- ^~' L 0 0`~140 14 1::0 t 130 13" ___ __ ___ __ ___ __ ___ __ c- 1 -0 1.-0 2. 0 3.0 0 1.0 2.0 3.0 1 0.O 2.0 30 1 60 160 - i -i -- -| 1 160 C I 1 1 150 —.2 10 05 -0 151 15 T at 0 U- 0 0~ 0 1. 0 2.1.03.0 0 3.0 1.0 2.0 3.0 0.3.0 3 13 13 20 r 2 0 Code 1 20..* 1 15 15 -0 —_ Total Deformation i 10 h 10 ----— Creep Deformation 10 0~( 4~~~~~~~~~~~~~~~~~~~~~ 14 5 % 50 1 - UnexposedIF I 0 10 1 1 3I 0 1. 0 2. 0 3.0 0 I. 0 2.0 3.0 0 1.0 2.0 3.0 Deformation - percent Deformation - percent Deformation - percent Figure 9. - Effect of Prior Creep Exposure at 650F on Room Temperature Tensile Properties of CI10M.

t> 10 hr Prior Creep at 700,F 50 hr Prior Creep at 700'F 100 hr Prior Creep at 700,F iW e o s..% o~II I' I tjn o o 1 t L,, 1, W0 16 160 1 160,. ISO 160 - 150 8 14n 140i -0 — Total Deformation 140 e 140. * 140 1 6p 0 -- Creep Deformation I 130 130I r 1n.0 2i.0 3-.0 4.-0 5, 0 6.30 0 1.0 2.0 3.0 13 0 1.0 2.0 3.0 180 - 180 / / I. 180 Io 170, O _ ] o 170 170 170 150 _ 0, 150 1 50 U) A40, z:,o,~ I, I, I, I, I, I, I I, I I 30, I- 0 I 140 1O4. O 140 3 ~n.130 130 130 0 1.0 2.0 3. 0 4.0 5. 0 6. 0 0 1.0 2.0 3. 0 25 IT 25 25 rs2! 1 0i a kt 15 1 5.1 5 0 0 1. 0 Z..0 X~ 3. 4.~ 5. 6. 0 0 0~. 0 2 0 3. 0 0'' 1 I Figure 10. - Effect of Prior Creep Exposure at 700'F on Room Temperature Tensile Properties of CI LOM

Q 10 hr Prior Creep at 800*F 50 hr Prior Creep at 800~F 100 hr Prior Creep at 800F 3 C 170 170 — I 170 _ _ — |, I 7 0 _-_ li a U Jl 160 1 60 16 O g6 150 5 150o___.0.so 00 140 - 140 140o - 30 130 1 130 0 1,0 2.0 3.0 0 1.0 2.0 3.0 0 1.0 20 3 160 r I' 160, 160| Code 150 150 0 Total Deformation 150 c * Creep Deformation t) 6 0 | OQ'Unexposed | 1 Un 1- 140 140 4^~ 9-. —*^ ~cr O -0~-0 —' — 0 F _ __ 130 - 30 — _ _ 130:: -- ___ 1- 120 - 20 30 F I 30 I 0 I, I. 30 i25- 0 25 —-- 2110 25- ^S 15 - - 15 F 15 0 20O1.0 2.0 3.0 0 1.0 2.0 3.0 0O 1.0 2.0 3.0 Deformation - percent Deformation - percent Deformation - percent Figure 11, - Effect of Prior Creep Exposure at 800-F on Room Temperature Tensile Properties of C110M.

> Prior Creep at 650'F Prior Creep at 700F Prior Creep at 800F,, 17E) I|-' - | - l -' 1701. -* | -| 170,' ~ - -00 hr [',10 hr I' ^ 150 ^.^ ^ -^l1nr- 50 -- ^ ---- ^ ^ --- -^ ^ ^ - 1500 hr 150 150 |! — ^ ^ 50 hr ^r^ --- ^^ - ^ —-- -y'' -'^ ^ 100hz o 130 130 130 160 --- 160 - * * - 50 --. 160 - ---' I - 16o 120 IZ0hr I 0150 50 0 hr 150 L~n 1.' 050 h 10Z0 h 140 -?i0 1~~0r-r ~140 - - 40 — 100 hr 130 - 130 /U130 F 130 120. hr. 13o /. I, l 160' I, 1 20' -,- 140.. 10r 1i0 l" h-o I 0 a~ - 120 I I 120 - o —120 l0h 5i 25 Total Deformation - 0 hr 2Total 0 hr - - 5Figure 12. - Sumary of Effect of Prior Creep Exposure on Room Temperature Tensile Properties of C/5M.0 z 15 105 hr o 0 1o 2, 3 0, 0 1, 0 20 I3 0 20 3. 0 Figure 12. -Summary of Efect of Prio Creep Exposre on Room Tmperature Tesile PrI, lz o [ i I,

Prior Creep at 650F 40 35 30 0 1.0 2.0 3,0 Total Deformation - Percent Prior Creep at 700'F U.. 40 o 35 Code, 0Y0 510 hr Exposure Time co 30 010 hrJ o I. %3t~nexjosed 0- 1.,0 2, 0 3, 0 Total Deformation - percent Prior Creep at 800*F 40 [35 t 30 0 1.0 2 0 3.0 Total Deformation - percent Figure 13. - Effect of Prior Creep Exposure in Hardness of C110M. WADC TR 57-150 Pt III 56

'''- I I I I 1 I'' I 1 Exposure Conditions Temp Time Stress Creep Def. Total Def. at^~~~ | ~Code Spec. No. ('F) (hr) (psi) (%) (%) A not exposed -- - H B 2CD31 800 100 nil C 3A8 650 100 82,000 0.26 1.00 1n D 1A11 700 50 82,000 2. 19 2.87 *^<5~~~~ |E 2A7A 700 100 51,000 0.32 0.68 -L~~ ~F 2AB2 800 10 28,000 0.58 0.79 un G 3CD18 800 50 22,500 2.16 2.32 0 160 140 I z 1 / I ^ / ^^ / I I^^ I I i-| I --— I I I I I I 120 100 0 0 o 80 40 O. 001 ~0 Strain - inches per inch tigure 14. - Representative Room Temperature Tensile Test Stress-Strain Curves of CIIOM after Prior Creep E

10 hr Prior Creep at 650'F 100 hr Prior Creep at 650'F Tested at 650F Tested at 650-F 130,,' 1 130 | b' k 4 120 120 U II HI'.9 90 I 0 a 10o 11.00. 0. i- -— 3 Code 1 S O 900 Total Deformation C).-L -~'-e —-fm —- Creep Deformation 00 100 100 - Unexposed o ~T 90 -90 I I I 0 1.0 2.0 3.0 0 1.0 2.0 3.0 4.0; 110 - - n10o - C n 3o 2 0 10 2.0 3. 0 00 1.0 200 3.90 - e5 fto 90 W U 80 IIi I - g 0 - I... I, I 0 1'. 0 2. d 30 0 13 0 2.0 3.0 4.0 25 25' -Do0 pc Dfm -p0 ]- g 10 - 10 - ~?~ 0 -—, I- I- I i,! 0.,' I I I, Deformation - percent Deformation - percent Figure 15. Effect nf h50*"P Ppinr r'-rP n F'-vrxCIn-re <r> A~mr TQ^C.^IO D-^^T~o-^i-1 r<- rf In'K

Tested at 700'F Tested at 700F < + 130' 130 I 120 - 120 0 -_n-OQ l 110 110 Code p..d,, O —O —.o - O — Total Deformation C D 0 ----- Creep Deformation I t6 100 O 100 X' Unexposed rt O0 1.0 2,0 3.0 90 0 1.0 2.0 3.0 4.0 1101' I' I. 1 110 )100 - 0Q - - 100 O 0?' 80 - 80 0-f - r 7 70. o O 1,.0 2.,0 3.0 0 1.0 2.0 3.0 4.0 215 2 —-----------------------— | 25 9 0 90 -' 0 5 - - 5 0 4r- 70 0 10 ~0 01.0 2.0 3.0 0 1.0 2.0 3.0 4.0 Deformation - percent Deformation - percent Figure 16. - Effect of 700*F Prior Creep Exposure on 700*F Tensile Properties of CLLOM.

10 hr Prior Creep at 800~F 100 hr Prior Creep at 800-F Tested at 800-F Tested at 800'F 130 1 130' 1" o 120 120 110 10 -10 100 - 100 9 90 *o @0 0 0 6( 880- 80 * oo I 00 700 *L *- - 70 0 0O 1.0 2. 0 3.0 O0 1. 0 2.0 3.0 X ^r * O " l I 1001 1 100 90 90 90 8DTR5-0APII6 ~Q) H~ 60 060@ *o 0 o 50- 60 --- o * 0 0 1.0 20 30 50 0 1,0 2,0 3,0 5C 50 —' —— I ——' —-- o ----- 70 4 40.pi I eO I c o 2 2 0 Total Deformation WoM 0 Creep Deformation ~ i.0 Unexposed IA@ 1o0 10 o0 I,-I,I., o _. _ _ __ _ __ _ _, _ __ WADC TR 57-150 Pt III 60

Tested at 65'nF Tested at 700'F Tested at 800~F 130' 130 13*| I Ii 10 -, I 30' I' J041 04 ~ 12 120 o ~ -2 - 120 I 0 U 0 U o, 10 h- L Prior Creep, ( _ J - 10 hrC c Unexpos edee 9 tt4 80 * U H 80F.., 80-, 80 80 a L n. I. I i.~,.. 1 70 70 00 70 o r -10 -50 100 - - 1 I00 3 70 3. 0 0 1.07 1 00 sb~ 90 90 - pe0 a - F e — aff o on E 50 50 5 * 0 40 40 _ Ce 30 30 - ~o~~T Pr etso Coa,1 1 -.. 70 o 70o Pir-Ce Ep u o l-dmea r 010~ I I I I, 90 M 9 / 90 80 C 8 0- 8 0 0^ -- -- o -' -- ~ -'-u 1.0 2.0 3.0 1.0 2.0 3.0 Deformation - percent Deformation - percent Deformation - percent Figure 18. - Summary of Effect of Prior Creep Exposure on Elevated Temperature Tensile Properties of CIlOM.

Exposure Conditions Test Temp Temp Time Stress Creep Def. Total Def. Code ( F) (F) (hr) Spec. No. (psi) (%) (%) A 650 not exposed B 650 650 100 2AB7 nil - C 650 650 100 2C25 95,200 0.69 2.31 D 700 not exposed - E 700 700 100 3C18C nil F 700 700 10 2C17C 90,500 0.50 1.43 120 G 800 not exposed - - H 800 800 10 1C15C nil I 800 800 100 3C15 14,000 0.94 1.05 110 100 / / / / / // - 0;001 — 90 Strain80 - inches per inch 70- D Creep Expo ure C 60T H 50 40 30 20 10 0 Strain - inches per inch Figure 19, - Representative Tensile Test Stress-Strain Curves at Elevated Temperature for C IOM after Prior Creep Expo:sure WADC TR 57-150 Pt III 62

bn 170-T ) 1Code u~ 16 O 650A'F0 Exposure.6 T 16070 0F Temperature WF^~ 15 0.H_ 800_.r 150 - Unexposed ~~ 130 - // 0. 1410 0ADC TR 57 —50 Pt0III.6 l zo C I 10M. WADC TR 57-150 Pt III 63

0.4 o 100 o Code 90 ~ 650*F Exposure Temperature rc A 700F and b |b A 0 800'F J Test Temperature Q 80 Ah _________________________ 800-1 ra 70.) - 650 o 0 800 04 5050 U 40 0 10 20 30 40 50 60 70 80 90 100 Exposure Time - hours Figure 21, - Effect of Unstressed Exposure at 650~, 700-, or 800F on Elevated Temperature Compression Yield Strength of CllOM, WADC TR 57-150 Pt III 64

> o Cd O —— 10 hr Prior Creep at 650'F 50 hr Prior Creem at 650F 100 hr Prior Creep at 650F Tested at Room Temperature Tested at Room Temperature Tested at Room Temperature o 140 140 -, I- 140 I I Code vt 130130 130 -- Total Deformation 130 L 20 — @- Creep Deformation *^?\4 Unexposed 120 c5 110 o 10 110o 1100L 0\ 0. > 0 11 0 20 30 0 10 0 0 10 2.0 30 90 90 90 0 1. 0 Z 0 3.0 0 1. 0 2.0 3.0 0. 0 1.. 0 0 Deformation - percent Deformation - percent Deformation - percent Figure 22. - Effect of Prior Creep at 650*F on Room Temperature Compression Yield Strength of C11OM.

C, 3 U, 0 o c 1 c Ir.o o""1 0 C o d e F | ov O w g g | * I 1 1 50 1' I' I' I'0 5 Ch,L —~0- Total Deformation - 14 0 140 40 r- 140 |5 1 — 0 — Creep Deformation 140 h. ~\. 130LC Unexposed 0 130 130 \0 130 \O 0 o0 un 9~09", 0, 1"0 120 0 0 0 2 120 1- 0 O2,'. sg no L \ — ^ - iioLX 5 6.726% II _o a110-1 572% 6, ~ * O 110L L ~ ~ o o 300 I, 300 -03 100 ^ 90 90 90 i 9 _ I _i _ - 0 1 0 1.0 0 30 0 1.0 0 3,0 0 1,0 2,0 3.0 Deformation - percent Deformation - percent Deformation - percent Figure 23. - Effect of Prior Creep Exposure at 700F on Room Temperature Compression Yield Strength of Cl OM,

U a U, 0 -Nl CI 10 hr Prior Creep at 800*F 50 hr Prior Creep at 8000F 100 hr Prior Creep at 800F CI(~ ~ Tested at Room TemPerature Tested at Room Temperature Tested at Room Temperature 160 160 160 Xd I 0 Code 15^ 150 -0- Total Deformation 150 --—. —- Creep Deformation U) 140^ —~~ ------- 140 - g Unexposed O0 co 14 140 * ^^^ 1401 140 0 0~~~~~~~~~~~~~~~~~0 @ ^ ~ ~13 130 *o @ 0 130 ON O~ O~~~.~~~~~~~~~~~~~ ~~~~~0 0 12 120 120 - 110 110o 1010 0 ______________________________ ___ I I 0 - 1.0 2.0 3.0 100 0 1.0 2.-0 3.0 100 0 10 20 3.0 D eformnation - percent Deformation - percent Deformation - percent Figure 24. - Effect of Prior Creep Exposure at 800F on Room Temperature Compression Yield Strength of C11 OM.

Cn U1 t+ Prior Creep at 650*F Prior Creep at 700-F Prior Creep at 800F TsTe erature Tested at Room Temperature Tested at Room Temperature o 160 --- " I I' I 1 160.. C o' e I 1 i60 o Code * 150 150 - 10 hr Prior Creep 150 150 150 K -- - 50 hr Time ------- 100 hr J 1 140 - 140.'0 Unexposed 140 130 130 130 00 hr 100hr o 120 1 2 120 120' ~~~50 hr, 1100 11 0o 50 1 00 1 0 - 100 10r 10 hr 10 hr 90 90 90 0 1.0 2.0 3.0 0 1.0 2.0 3.0 0 1.0 2. 3.0 Deformation - percent Deformation - percent Deformation - percent Figure 25. - Summary of Effect of Prior Creep Exposure at 650', 700' or 800~F on Room Temperature Compression Yield Strength of Cl1OM.

160I Exposure Conditions 150 - emp Time Stress Creep Del.Total Def. Code Spec. No. (-F) (hr) (psi) (%) (%) A not exposed B 3CD13 650 50 nil -- - 140 C- 3CD9 700 10 nil - -- D ICC32 800 10 nil -- - E 1C18 650 100 82,000 0.38 1. 10 F ICD6 650 100 95,900 1.24 3.43 130 G 2A2 700 10 62,000 0.32 0.94 - H 3C29 800 10 21,000 0.42 0.57 I 3AB27 800 50 25,000 2.78 2.98 120 110 - 100 90 A 80 B k ID E o 70 G 60 - WADC TR 57-150 Pt III 69 40 30 20 10 0.001 0 Strain - inches per inch Figure 26. - Reprecentative Compression Test Stress Strain Curves at Room Temperature for CIeOM after Prior Creep Expos ure. WADC TR 57-150 Pt III 69

> (? Ul Un 0 90 90 I 90 9Code a) 80 -O- Total Deformation 80 ^>4 | —--- Creep Deformation F j^ Unexposed r.2 70 - 70 05-n 0 *\ 0 5 0o' 40 40 0 ll 60^ -- ^ - 60 0 1,0 2.0 3.0 0 1,0 2.0 3,0 Deformation - percent Deformation - percent Figure 27, - Effect of Prior Creep Exposure at 650 on 650 Compression Yield Strength of C 1IM.

C2 H U, U-i Tested at 700'F Tested at 700'F 90 906 i i I Code:>~~' ~r 80 ~ -0 —- Total Deformation 800 H~~~~~~~~~~~~~~~~ Dfr i pCreep Deformation Figure 28' Unexposed,ao 70 C OM ka-4J 60 0\ EO~~~~~~~~ 60 0 ~~~~ Ln~~~~b Ir 50~ 50 ^l~~~~~~~Q i-i~ ~ ~~~~~~~~~0 4J 40 40 0 1. 0 2. 0 3. 0 0 1. 0 2- O 0 Deformation percent Deformation percent Figure 28, - Effect of Prior Creep Exposure at 700'F on 700'F Compressio OT of C1ode

Uc C) 1-3 90 90.....'3Or 7 70 0 70 0 * 8 00 - 80 CD 0 Code -4 6 6,85% o A 0 Total Deformation U * Creep Deformation 50 50 > 50-I Ii 50 C Unexposed (~ O0 X' iO 1. 0 o2. 3.0 0 1.0 2.0 3.0 4.0 Deformation - percent Deformation - percent Figure 29. - Effect of Prior Creep Exposure at 800'F on 800F Compression Yield Strength of C1IOM.

Qn elfo re;~ t65~ Prior Creen at 700-F Prior Creep at 8(0~ w ~~~~Tested at 650 *F Tested at 700'F ~Tested at 800*3 90 F;90 9 9 Code U, 0( P80 1o 0 hra Prior Creep at 8080 0 80L - 100 hr} Time expo Unexposed N / 10 h C 70 70 O a70 l 0hr -4 0 CD~~~~~~~~~~ O'T ~ ~ ~ ~ ~ ~ k CC) (L /1 ~~~~~~~~~~~~~~00 hr r o CD 60C ~60 Ni 6o - l1hr 10 hr 100 hr h H O O Ln 0 -- 0 0 c, ~7 0 2. IZ 1,0 2,0 3,Q-0 0 1,0 2, 0 3,0 o 0 1,0 2,0 3,0 4.0 Deformation - percent Deformation - percent Deformation - percent Figure 30. - Summary of Effect of Prior Creep Exposure at 6504, 700', or 800"F on Elevated Temperature Compression Yield Strength of CliOMi

i ] I [! [ I! I I I I I [ I I ~^~~~~~> |Test Exposure Conditions Q~t~~~~~~ ~~~Temp Temp Time Stress Creep Def. Total Del. (C Code Spec. No. ('F) ('F) (hr) (psi) (%) (%)'"j~3 |A 650 not exposed ~^a~ ~B 2A24 650 650 100 nil (U _ C 3A34A 650 650 100 95,200 0.68 1.44 -41 D 700 not exposed ~* ~E 1CC28 700 700 50 nil-;**;I~~~ ~F 2CD4 700 700 10 90,500 0.46 1.34 o G 1C36C 700 700 100 36,000 0,31 0.58 H 800 not exposed uCdt ~I 3AB24 800 800 10 nil J 2CD15 800 800 10 21,000 0.45 0.61 H-~ 100 K 2CD1 800 800 100 28,000 6.66 6.85 C 90 O 80 0 0 40 A B C/ E Gz H/ I/// K 30 10 80 - 40 * A B C D E F G H I J K Strain - inches per inch Figure 31. - Representative Compression Test Stress-Strain Curves at Elevated Temperature Following Prior Creep Exposure.

100 I I II -=I'-4-4, 90 _ O a, -/..: 80 -! o - - 6 0 700 -F ^ 60 ^0-^^^^^. s^-"^700~ 50 0 H AO 0)~~40 40 - 4- Code 30 m 30 - -_ a)i |~~~~ 0 650~F:~,~~H IA 700'.F Exposure g 20- A 70 F Temperature o 0 800 F 0 P4 1o 0 Unexposed 0 10 20 30 40 50 60 70 80 90 100 Exposure Time - Hours Figure 32, - Effect of Unstressed Exposure on Room Temperature Tension-Impact Strength of C 1 OM. WADC TR 57-150 Pt III 75

100 Q 90, — 80 Cd UD 70 ( 60' ~ 50 800'F __40 ^- 6 650 0 4 0 Code 4- 30 ---- h 30O 650*F Exposure Temperatur 7 A 700'F and 20 Test Temperature 10 H I 0 800'F r 10 0 10 20 30 40 50 60 70 80 90 100 Exposure Time - Hours Figure 33. - Effect of Unstressed Exposure on Elevated Temperature Tension-Impact Strength of C 11OM, WADC TR 57-150 Pt III 76

> Il ~- ________Prior Creep at 700'F Un 100 hr Prior Creep at 650'F Tested at Room Temperature 100 hr Prior Creep at 800F Tested at Room Temperature o Tested at Room Temperature 10 hr Prior Creep Time 100 hr Prior Creep Time este aoom emrature,-, L 90 I I' I 90 0 9. L'' B0 80 80 800 k \\ /0-\ O 1070 2, 3. 70 2.0 70 1. 70 - O 70e 0OF C.6 60_ \ —-------- 60 0 660 60 -^., So 50 0 50 50 Code 40~ - -O- Total Deformation 40 F g r 3 - E f c of P i r C e p —O —Creep Deform ation.0' Unexposed 30 30 30 - 30 20 20 - 20 - 20 - 0 o 0 19 - 10 10 I 10 0 01.0 2,0 3.0 0 1.0 2.0 0 0 1,0 2.0 0 0 1.0 2.0 3.0 Deformation - percent Deformation -percent Deformation - percent Deformation - percent Figure 34. - Effect of Prior Creep Exposure on Room Temperature Tension-Impact Strength of C110M.

n l7j (I' 100 hr Prior Creep at 650'F Prior Creep at 700*F Teste at-FTested at 700'F 100 hr Prior Creep at 800F _Tested at 650-F 10 hr Prior Creep 100 hr Prior Creep Tested at 800F 60 60 | | 60 so 1 01 ~ I 0 ~0 ^i ^ t3 *5 ~~4iCode U 000 -- 2 3 0 130 0Total Deformation | 3 2.9 0 peren --- - Creep Deformation o Fiur10 - Ef 10 H 10 L 10 sO * o o 0o Q i 0 * I I o I I f I 0.J 0 0- O c 0 ~. o. 0 2.-0 3. r 00 1.0 0 ~- o 0 1.0 -. 0 3.0 0.'.-0 3. 0 Deformation - percent Deformation - percent Deformation - percent Deformation - percent Figure 3. - Effect of Prior Creep Exposure on Elevated Temperature Tension-Impact Strengths of C I10M.

Note: University of Michigan Data Points ~ 1- Superimposed on Fig. 16 of TML a~ L Report No. 43. 120 arw O NACA so L?X ^ 80 - 40 60 rLi 80CTR5-50P II7 c 4Q -,,4-4 0 Univ, of Mich. S C Data Points 0 0 200 400 600 800 1000 Test Temperature -'F Figure 36, - Effect of Temperature on Compression Yield Strength of CIOM -- Comparison of University of Michigan Data for C1IOM With Data from the Literature, WADC TR 57-150 Pt III 79

150 140 130 120 110 100 90 80 So 80 70. 60 0 30 Ut. 5I 50 Yield 20 40 - ^ ^ ^ ^ ^ ^ ^110 As Rec, 800'-100 hr As Rec. 800'-100 hr As Rec, 800'-100 hr Heat A5036 Heat A1172600 Heat A50089 Source of: (WADC TR 54-54) (Present Investigation) (Republic Aviation) Material Figure 37, - Effect of 100-Hour Unstressed Exposure on Room Temperature Tension and Compression Properties of Three Heats of CIIOM. WADC TR 57-150 Pt III 80 Fi Ir 37, 4 Efec f IA100- W-Ho wu TT-rIk l~nM A'., I- Un tes e lxo u ea on rr A - - Room Tempera -tu-re

150 140 130 / 120 110 - 100 90 O 80 80 70 -u 60 50 40 - 30 - 20~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0 10 Strain inches per inch 10 20 30 40 50 o 60 S 70 0? 0 90 u 100 110 120 130 Figure 38. - Tension and Compression Stress -Strain Curves at Room Temperature for Two Heats of ClIOM -- Specimens taken longitudinal to the sheet rolling direction. WADC TR 57-150 Pt III 81

10 hr Prior Creep at 650-F 50 hr Prior Creep at 650-F 100 hr Prior Creep at 650-F 150 150 150 14 7140 140 Code ~0!!,300/-C 1- 30 - 130 13C3Z10A. __Compression Strength S*, 120 120 120 \ x1 A As received U3 o\ o \. oU 1j0 1 0 150 140 100 100 012, 10 120,I~ 90 1.0 2.0 3.0 900 1.0 Z. 0 3.0 90 1.0 2.0 3.0 10 hr Prior Creep at 700*F 50 hr Prior Creep at 700*F 100 hr Prior Creep at 800*F 160-1 I| -160 1 - I 160-1. | - i150F'150 150 F y 140 140 - 40.a 130 130 130 -- h, g~ 120 120 - 120 1110 110 100 0 1.0 2.0 3. 0 0 1.0 2.0 3.0 0 1.0 2,0 3.0 0 hCreep DefPriorm ation - percent Creep DefPriorm ation - percent Creep Def 100 hr Priormation - percent Conditions. [E 120 120 - 120900 1.0 2. 0 3.0 9 0 1.0 2.0 3.0 0 1.0 2.0 3. 0 Creep Deformation - percent Creep Deformation - percent Creep Deformation Figure 39. - Tensile and Compression Yield Strengths of C 130M at Room Temperature Versus Creep Deformation for

10 hr Prior Creep at 650*F 100 hr Prior Creep at 650*F 1001| 100, 90 90 0 0 * 80 - 80 - Code tz |7 Tension Yield u P70- 70 --- Compression Strength X A r\'A.y As received. 62 \04, ~~6 \ 50 \ 50 o \ tn o 401. I * I I -01. I I I 0 1.0 2,0 3,0 0 1.0 2.0 3.0 10 hr Prior Creep at 700'F 100 hr Prior Creep at 700'F 1001 -- - I-' 100l,'' 80 80 o 90 I I 90 1 oI o a 40 40 5 0 0 - 40 1.0 2.0 3.0 0 1.0 2.0 3.0 10 hr Prior Creep at 800'd 100 hr Prior Creep at 800EF W 80A- 80 100' 60-' 60 I -I4 * 50- 50 0 00 10 2.0 3,0 O 1.0 2. 3,0 Creep Deformation - percent Creep Deformation - percent Figure 40, - Tensile and Compression Yield Strengths of CIOM at Elevated Temperature After Indicated Prior Creep Exposure, WADC TR 57-150 Pt III 83

,178 III:d OSI-L.S HI OCVrl M *'ain4:3aduuajI juookt:1e pa4saj, INOI I Jo s^eaH o0lj JO sq42uazj4 uoTss~aduioD pue uoEsuaIj as.raASU'e.jL aJo -euPpn4tcuorT uo jo008 W1e aansodxa passaairsufl inoH-001 JO 4aJJ" - *7 a.Tn TI 009ZL.IIV 9-0sV 009VZLI I 90SV'ON o:aH *,dx3 *okI sV,'dxa'oai s *,'dxa' odx aHi sv *'dxa'*oal s t uo!Tpuo _ / 7 - — 0 / I/ / L,, 0 -// ^ ^ ^^ // // / -o01 -^ ^ ^ ^^ / /O /, / / //,,/ / / /,//. //, ~ ~~~~~~~~/ / / n09/ / */ / OL / / / / / / / 00 1, / -// // // /,// 0,- j./. /. /A / / / / - o/ _ ~ ~ -091 ___________________ ^________________ *it I ZIo008 -'z 001 -,'dx30

t,1,- - ~-,, - -,-,, -. *....,,.,:: ^ ^ "x ^ ^ ^ ^ & s?;?.. Tens~'~:~'~-"~:::ile.:'........ 142,......vg)'.<' Creep..... ). ~......:~"~'.. Y.'''''... i:.~ ~-.::.~!.~.~:'::.iv.:~.~.:..~.....'iC4.~?.:~:~./.,.`.- v A'''t - a ~................. ~...s..:.. ~. -....~..~.......:..~...~......:...''..:~.........:-............::...... %..t./:'/:. -".S"'n'sile..' * *... i ~.,'ix, <"'*....'., S. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~>..,S <,.'. ~,~. 4-'.',S........'^:'......~. ~:'.."~'..X...... ~ *'..::"'. Tensile~~ Yiel 142,90 Cree Df.) 21,r0e0ps iD(O. 3 *-omp-e-s-on Room Temp. Properties TnieYield. 101 75,00 avUlt. Tensile 144,000 Compression ~~~~~~~~~~~~~ ~~~~~~~~~~Tensile Yield 1347,000 Yield 80-90,000 (est) ~~~~~~~~~~~~~~~~~~Compression Yield 114,000 (est) W'DTR''....._.150.-;~..... III~.85-. ~'". —:". e'~'..':'y......~"::,... ^ ^ ^ ^...............~;-*" ~.' ~........'......."............'..............................'-~-:."<"'"*~..........:~/...~'~'~'~..~..%~;,~.~-,C..i'~ ~:~ c,~):?.~?...,,:..~ ~...?~,~:'<~.. ~~'i~:',::~'.;J: ~ S~.:~,~..'~....:-~**' ~....~.....'-.:...........::x..~.,'.......' ~:..'.~i" }r..,~' ~',*p....-~-.. ~..~-'.f~'~. —,~. ~:'~, **........~ /~'.... ~...,.,......:....':~:,.......::-..~,;' >,::t":.,..,';;:...-~,~....:~:'i~''.:~.'.. r':.-;~'~" X'"': ~.......:'':. "1 -'~...,.' ~:~-~'~ ~<~-"~.~'~..'|':5;:::-:~":,~*';~"~.<"~<:'::::~.............-"'":':.:~'?,...:: Y"".'t*':.,:,' ~.'".'t..........:':~..... ~.~ %"'.^-^.*-^<<..........":-..,..^.,-^....^**<;- ""y'.^'^::;t:'^ ^;^.^:<.^'^ -^ ^ ".:::='. ~'~:M ~ >*~.X' ~ "~.....'::'"...... "'% "":" ~":':'~"*::;'*"~:..........~"'; >:* X1000 X1000 Figure 44. - C110OM Exps-Prduceour F ig ure 43. - C I110M Exposed 100 Room~~~~a Temp. andopertiesps hours at 6500T and Ult.~~~~~~~~5 esie - 144,20 Crep ef) 82,I 000 psi (0. 26% C mrsinRoom Temp, PropertiesCreDf, Yil 0,10(v)Ult. Tensile 17750,000 e pPrprte rr,, i a; I=h V cI A 7rnnn ltTensileYil 1449000 -'T "^'*;...',':-^'''^'i,.^.' -Ty-11'..^' ^ r^^^lw^::;!^,^,y^^?^"~;*^^'^^~~~~~~~~~~~~~~~~~~~~~~~~...:~. v~,.'::"'............'"::~'"~'*~:::~' **' *'' r 1.^ ^ -' -..-!""'r<*"' ^O -y -^'"":'r''" ^ * ^ r~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~rS:"'*''i'i * 1'""::'{*;.?''" ":* " "':':^ 3;"';&.. X1000 X1000 Figure 44. - Cl0M AsProsdu10cour Figure 43. - Cl10M Exposed 100 at TOOT and 100,000 psihours at 8500F and (5.44% Creep Def.) ~~21,000 psi (0.33% RomTensil Yrpriesd1290 ag Creep Def. ) Comprssio _.,Room Temp. Properties Uli ensld 108,000 ---— vg ----- Tensile Yield. 175,000Ult. Tensile 150,000 Corrmrpssion ~~~~~Tensile Yield 1347,000 Y-i~ld 80-9,000 (est)Compression Yield 1304,000 (est):.D'..- 5715't II 85'...."'' ";~~~~

APPENDIX I STATISTICAL INVESTIGATION OF TEST DATA* The short-time mechanical property data for the base (unexposed) condition of heat A 1172600 were analyzed to establish the variance in normal properties. Such information is useful in evaluating the signficance of changes in properties with creep exposure. In the present investigation, the normal properties were generally evaluated by nine duplicate tests at each temperature. Three tests each were run from the three sheets selected for study from among the eleven purchased. The properties reported in Tables 2, 3, and 4 included the average of tests within a sheet and the average of all tests. The effect of creep exposure on subsequent properties was evaluated with respect to the average of all tests. Generally the variance of a set of data is the square of the standard deviation of the data, however, where samples sizes are small, i. e., less than about 30 observations, variance is given by the following formula s2 = E..a (x - X N- 1 where s2 = variance of test results X = test result X = average of all results N = number of tests For the number of samples studied in these tests "s" has almost the same properties as does sigma in a normal distribution and thus 95% of all points will fall between limits of +2s from the mean value. The following tabulation gives the results of calculations of the variance of the various mechanical properties evaluated in this investigation: (It should be noted that because of the small sample size studied, one value having a large deviation from the average can greatly affect the calculated variance, ) * The nomenclature used in this section is taken from "Quality Control and Industrial Statistics" by A. J. Duncan, Richard D. Irwin, Inc., Homewood, Illinois, 1952. WADC TR 57-150 Pt III 86

Variance Computation for Mechanical Properties of CLIOM (Heat A1172600) Temp. s Property (*F) (Av'g) "s" 2 s (95% conf) (Av'g.) (To) Ult. room 146,200 psi 2840 psi 5680 psi 1.94 Tensile 650 110,700 2240 4480 2. 02 700 105,500 4160* 8320 3.92 800 92,500 2 105 42 10 2.28 Tensile room 142,900 2480 4960 1.74 Yield 650 96,000 2520 5040 2.62 600 92,700 4180* 8360 4.53 800 84, 100 2220 4440 2.64 Compression room 108, 100 1760 3520 1.63 Yield 650 61,000 5320 10640 8.74 700 57,200 2640 5280 4.61 800 56,300 3120 6240 5.54 Tension- room 56 ft-lb 13. 26. 23.2 Impact 650 46 2.7 5.4 5.86 700 44 2.5 5. 5.68 800 43 2.4 4.8 5.58 * high value of "s" because one test had large deviation from average. Bartlett Test Results 95% confidence 1. Ult. Tensile - variance is homogeneous for all temp., therefore +2s avg. = 5. 08% 2. Tensile Yield - variance is homogeneous for all temp., therefore +2s avg. = 5.72% 3. Comp. Yield - variance is homogeneous for all temp., therefore +2s avg. = 10. 26% 4. Tension-Impact - variance is homogeneous only for 650', 700, 800'F, therefore ~2s avg. = 11.40% WADC TR 57-150 Pt III 87

In all cases, the calculated "s" was also expressed as a percentage of the base value at the given test temperature. The effect of testing temperature on the variance was determined using the Bartlett test for homogeniety of variances. The results of this analysis showed that the variances in the ultimate tensile strength, tensile yield, and compression yield were homogeneous for all test temperatures, and the elevated temperature tension-impact variances were homogeneous but the room temperature results were not, Consequently, the variances calculated for each temperature were expressed as a percentage of the base value and average +2s limits were computed for each mechanical property. The results indicate that the 95 percent confidence limits of the tensile ultimate and yield strengths fall between approximately +5 percent of the base value, while the limits for the compression yield strength and elevated temperature tension-impact strengths fall at about +10 percent. Room temperature tension-impact tests were considerably more subject to scatter, with a +4 6 percent limitation on the 95 percent confidence limit. These confidence limits form a rough means for the evaluation of the effects of creep-exposure and enable a better understanding to be gained of the scatter in test points from the trend lines drawn expressing the relationship between prior deformation and residual properties. This is particularly evident in the case of Figures 34 and 35, the plots of tension-impact properties. It should be realized, however, that the variance of the unexposed condition does not necessarily apply to conditions of exposure to stress and/or temperature for varying amounts of time. If the variance changes as a result of such exposure, a statistical treatment of the significance of exposure becomes a complicated analysis of the difference between the means of two small independent samples with unequal values of sigma. If the sigmas can be assumed equal and the universes are normal, then the results can be analyzed with confidence. Any deviation from these conditions must necessarily limit the effectiveness of statistical analysis. If the assumption could not be made that exposure conditions had no effect on the variance then a sufficient number of samples would have to be evaluated at a given set of exposure conditions to permit calculation of the variance. Assuming that the variance was constant, a computation was made of the change in ultimate tensile strength that would be required in order to be significant with respect to the base condition. This consisted of a comparison of one test point versus the nine base points. The average change required was about 4. 9 percent of the base strength, a value that compares quite well with the i5 percent computed for the 95 percent confidence limits of this property. It was then assumed that the confidence limits were an adequate expression of range of strengths to be normally expected. Test points and trend lines falling outside these limits probably represent significant changes. WADC TR 57-150 Pt III 88