THE UNIVERSITY OF MICHIGAN COLLEGE OF ENGINEERING Department of Chemical and Metallurgical Engineering THE MECHANICAL PROPERTIES AT 800~, 1000~ AND 1200F OF TWO SUPERALLOYS UNDER CONSIDERATION FOR USE IN THE SUPERS$ONI: TR-ANSPORT Y _-SXr - i '........ '';., 2 w.. ' > s -. i _ -;.., ~, \ A ^ *..i -; /,,.' A,,; ' ', 1; ^ - T.. M. Cuillen J. W. ^^e-,an ORA Project 04368 prepared for: NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Grant NsG-124-61 Washington 25, D. C. administered through: OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR April 10, 1964

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SUMMARY An investigation has been conducted in which the upper temperature of usefulness of two nickel-base superalloys was established within relatively narrow limits for application in the proposed supersonic transport. These alloys, Rene' 41 and Waspaloy, were each studied in two conditions of prior treatment to evaluate the maximum temperature at which they exhibited sufficient levels of creep strength, rupture strength and resistance to the presence of sharp edge-notches for use in the SST. It has been determined that the upper use temperature of these alloys is limited by their behavior in the presence of sharp edge-notches and stress concentrations. The sharp notches were used to simulate cracks in the materials. The alloys exhibited satisfactory resistance to the notches and the stress concentrations at 800~F but not at 1000~ or 1200~F. The sensitivity of the alloys to notches and stress concentrations has been related to their creep resistance in the temperature range from 1000~ to 1200~F. With a few exceptions the creep strength and the rupture strength of the alloys exceeded the minimum requirements for application in the supersonic transport for temperatures up to 1200~F. The alloys in the cold reduced and aged condition showed higher properties than the same materials tested in the annealed and aged condition. Use in certain sections of the SST will require materials to withstand prolonged exposure to temperatures of approximately 1200~F. Rene' 41 and Waspaloy in the conditions of prior treatment in which they were tested in this investigation are not considered to be satisfactory for application in the SST at temperatures much above 800~F. It should be recognized that there may be conditions of working and/or heat treatment in which these alloys will not be subject to the limitations found in this investigation. From the opposite point of view, it is possible that other alloys being considered for the SST could be subject to the same low notched specimen rupture life at temperatures where appreciable creep can occur. ii

TABLE OF CONTENTS PAGE INTRODUCTION....... EXPERIMENTAL MATERIALS. EXPERIMENTAL PROCEDURES. Test Specimens.. Unnotched Specimens Notched Specimens. Creep and Rupture Tests 1 2 2 3 3 3 4 Tensile Tests..... RESULTS AND DISCUSSION.. 5 5 Rene' 41............. Annealed and Aged Condition Cold Reduced and Aged Condition. Waspaloy......... Annealed and Aged Condition Cold Reduced and Aged Condition....I 5.... 6 ~.~.~.~ 7 11 11 12 Applicability of Results Stress for Rupture in Creep Resistance. Notch Resistance. 50, 000 Hours. 14 15 16 16 CONCLUSIONS. REFERENCES. 18 20 iii

LIST OF TABLES TABLE PAGE I Chemical Compositions of Experimental Materials.. 21 II Creep and Rupture Data from Smooth Specimens of Rene' 41 in the Annealed and Aged Condition.... 22 III Rupture Data from Notched Specimens of Rene' 41 in the Annealed and Aged Condition.... 23 IV Tensile Properties at Room Temperature of Interrupted Specimens of Rene' 41 in the Annealed and Aged Condition........ 24 V Creep and Rupture Data from Smooth Specimens of Rene' 41 in the Cold Worked and Aged Condition.. 25 VI Rupture Data from Notched Specimens of Rene' 41 in the Cold Worked and Aged Condition.. 26 VII Tensile Properties at Room Temperature of Interrupted Specimens of Rene' 41 in the Cold Worked and Aged Condition...... 28 VIII Influence of Plastic Strain and Stressed Exposure at 1000~F for 1000 Hours on the Tensile Properties of Rene' 41 in the Cold Worked and Aged Condition.. 29 IX Creep and Rupture Data from Smooth Specimens of Waspaloy in the Annealed and Aged Condition.. 30 X Rupture Data from Notched Specimens of Waspaloy in the Annealed and Aged Condition... 31 XI Room Temperature Tensile Properties of Interrupted Specimens of Waspaloy in the Annealed and Aged Condition................ 32 XII Creep and Rupture Data from Smooth Specimens of Waspaloy in the Cold Worked and Aged Condition... 33 iv

LIST OF TABLES (continued) TABLE PAGE XIII Rupture Data from Notched Specimens of Waspaloy in the Cold Worked and Aged Condition... 34 XIV Room Temperature Tensile Properties of Interrupted Specimens of Waspaloy in the Cold Worked and Aged Condition...... 35 XV Influence of Plastic Strain and Stressed Exposure at 1000~F for 1000 Hours on the Tensile Properties of Waspaloy in the Cold Worked and Aged Condition.. 36 XVI Influence of Notch Acuity on the Rupture Properties of Waspaloy in the Cold Worked and Aged Condition.37 XVII Stress for Rupture in 50,000 Hours... 38 XVIII Stress for a Minimum Creep Rate of 0. 000001 Percent per Hour....... 39 XIX Estimated Minimum Time for Rupture of Notched Specimens under a Net Section Stress of 40, 000 psi.40 v

LIST OF FIGURES FIGURE PAGE 1 2 3 4 5 Types of Test Specimens.......... Stress Versus Rupture Time Curves for Smooth Specimens of Rene' 41 in the Annealed and Aged Condition...... Stress Versus Rupture Time Curves for Notched Specimens of Rene' 41 in the Annealed and Aged Condition............. Stress Versus Minimum Creep Rate Curves for Rene' 41 in the Annealed and Aged Condition Stress Versus Rupture Time Curves for Smooth Specimens of Rene' 41 in the Cold Worked and Aged Condition..... 41 42 43 44 45 6 7 Stress Versus Rupture Time Curves for Notched Specimens of Rene' 41 in the Cold Worked and Aged Condition.............. Stress Versus Minimum Creep Rate Curves for Rene' 41 in the Cold Worked and Aged Condition. 46 47 8 9 10 Influence of Plastic Strain Introduced Prior to Stressed Exposure on the Ultimate Tensile Strength of Rene' 41 in the Cold Worked and Aged Condition...... Stress Versus Rupture Time Curves for Smooth Specimens of Waspaloy in the Annealed and Aged Condition.............. Stress Versus Rupture Time Curves for Notched Specimens of Waspaloy in the Annealed and Aged Condition................ 48 49 50 vi

LIST OF FIGURES (continued) FIGURE PAGE 11 Stress Versus Minimum Creep Rate Curves for Waspaloy in the Annealed and Aged Condition.. 51 12 Stress Versus Rupture Time Curves for Smooth Specimens of Waspaloy in the Cold Worked and Aged Condition............ 52 13 Stress Versus Rupture Time Curves for Notched Specimens of Waspaloy in the Cold Worked and Aged Condition....... 53 14 Stress Versus Minimum Creep Rate Curves for Waspaloy in the Cold Worked and Aged Condition.. 54 15 Influence of Plastic Strain Introduced Prior to Stressed Exposure on the Tensile Properties of Waspaloy in the Cold Worked and Aged Condition.. 55 1ii

IN TRODUC FION As an outgrowth of a screening program (Ref, 1) designed to evaluate the applicability of superalloy sheet materials to the construction of the trisonic transport a study has oeen carried out at the University of Michigan to help establish the upper temperature of usefulness of these materials. In order to limit the breadth of the program, two of the more promising alloys of this type, Rene' 41 and Waspaloy, were used in this study Each of these alloys was tested in two conditions of thermal and mechanical treatment The creep and rupture properties of the alloys were determined at temperatures from 800' to 12000F and these properties were used to evaluate the upper temperature of usefulness of the materials In the original screening program specimens with ASTM sharp edgenotches were exposed for 1000 hours under a stress of 40, 000 psi at various temperatures These tests were included in the screening program as a measure of the resistance of the materials to unstable crack propagation. During exposure several of the notched specimens failed while other notched specimens of the same alloy survived the exposureThese latter specimens had subsequent tensile properties similar to the unexposed material. The failure of some of the specimens during exposure led to the inclusion in the current program of a number of tests designed to measure the "stress-rupture time" characteristics of specimens containing sharp edge-notches The parameters which have been applied to the data for the purpose of arriving at an upper temperature of usefulness were: 1. Stress for rupture in 50, 000 hours as obtained by extrapolation of tests out to approximately 3000 hours. 2 Stress to prociuce 0. 1 percent creep in 50, 000 hours. 3 lllrnimulm tilme for rupture of spec imerns containin the ASTM sharp edge-notch at a stress of 40, 000 psi, These reference parameters were selected because: (1) the aircraft 1

is expected to have an operating life of up to 50, 000 hours; (2) the total amount of creep which can be tolerated during the operating life is approximately 0. 1 percent; and (3) 40,000 psi is a reasonable compromise for the expected service stresses in the civilian supersonic transport. EXPERIMENTAL MATERIALS The alloys used in this investigation were in the form of 0. 030-inch thick sheet material. These alloys, Rene' 41 and Waspaloy, were each studied in two conditions of prior treatment. These conditions were as follows: Rene' 41 - (1) Annealed and aged for 16 hours at 1400~F, (2) Cold reduced 35 percent and aged for 2 hours at 1500~F. Waspaloy- (1) Annealed and aged for 16 hours at 1400~F. (2) Cold reduced 40 percent and aged for 2 hours at 1500~F. The heat numbers and reported chemical compositions of these materials are listed in Table I. Both of the alloys were obtained from the General Electric Company, Metallurgical Products Department. The materials were received in the annealed condition and in the cold reduced condition. Specimen blanks were cut from the sheets and stamped with an identifying code. These blanks were then aged in an electric furnace prior to being machined into the finished specimens. EXPERIMENTAL PROCEDURES The upper temperature of usefulness of the two alloys was studied by tests at 800~, 10000 and 1200~F. The test program involved the use of tensile, creep and stress-rupture tests on both smooth and notched specimens. The great majority of the notched specimens contained the ASTM sharp edge-notch which yields a theoretical elastic stress concentration factor of >20. Properties in both the longitudinal and transverse directions were measured to avoid misleading results from anisotropy effects which might be present in the alloys. 2

Test Specimens Un notclled Specir m ens The configuration of the smooth specimens used to measure unnotched properties (Kt = 1. 0) is shown in Figure la, Specimens were prepared from rectangular blocks by milling. Ten specimens were machined at a time, using a fixture to clamp the blanks together and assure accurate alignment throughout the machining operation. Notched Specimens A few rupture tests were conducted during the program on specimens which contained notches of intermediate acuities. The geometry of the specimens with Kt's of 1. 5, 2. 1, 3, 1, 5. 9 and 9.4 is shown in Figure lb. In these specimens only the notch root radius was changed to vary the stress concentration factor. The values of the notch root radius for the different Kt's are as follows: Stress Concentration Notch Root Radius, Factor, Kt inch 1.5 0.250 2.1 0.100 3.1 0.040 5.9 0.010 9.4 0.0036 >20 <0.0007 The majority of the notched specimens tested contained the sharp edge-notch recommended by the ASTM (Ref. 2). The configuration of this specimen is shown in Figure Ic. As was the case with the unnotched specimens, ten blanks were machined at one time, using a second fixture to maintain alignment. The reduced section of the specimen was first milled to size. The notches were then ground almost to size, with an alundum wheel having a 60-degree included angle. The notch root radii for stress concentration factors of 1. 5 to 9. 4 were lapped to final dimensions. The final radii of the sharp notches were obtained by drawing a sharp carbide tool through the notches. Root radii and net section widths were then measured using a 50X optical comparator. 3

Creep and Rupture Tests The creep and stress-rupture tests were conducted in individual University of Michigan creep-testing machines. In these units, the stress is applied through a third-class lever system having a lever arm ratio of about 10 to 1. The specimen was gripped by means of pins passed through each end of the specimen and into holders which fitted into a universal joint-type assembly for uniaxial loading. Heating was provided by a resistance furnace which fitted over the specimen and holder assembly. Strain measurements were taken on the smooth specimens by means of a modified Martens optical extensometer system. Extensometer bars in pairs were attached to collars clamped onto the gage section of the specimens. Placed between the pairs of extensometer bars were the stems of mirror assemblies which reflected an illuminated scale located about five feet in front of the creep unit. The differential movements of the top and bottom pairs of extensometer bars caused a rotation of the mirrors, which was observed through a telescope mounted next to the illuminated scale. As the specimen elongated, a very small movement of the extensometer rods was magnified by the resulting optical lever and converted into a large change in the reflected scale reading. This system permitted the detection of a specimen strain of about 10 millionths of an inch. Strain measurements were made as each weight was applied during loading. Creep strain was read periodically through the test. When failure occurred an automatic timer was activated by the fall of the specimen holder measuring the rupture time to one-tenth of an hour. Three thermocouples were attached to each of the creep and rupture specimens at the center and at either end. All the thermocouples were shielded from direct radiation. Prior to starting a test the furnace was heated to within 50~F of the desired temperature. The specimen was then placed in the hot furnace and brought up to the test temperature and distribution in a period of not more than four hours. ASTM recommended practices were followed in controlling the test temperature and distribution. 4

Strain measurements were not taken on the notched specimens. The procedures followed for the attainment of the proper test temperature and distribution were the same as those used for the unnotched specimens. In a number of cases the stressed exposure tests were interrupted before rupture of the specimens. In these cases the furnace was turned off as the required time and the specimen was cooled under load to minimize the effects of creep recovery. Tensile Tests All tensile tests were conducted with a 60, 000-pound capacity hydraulic tensile machine. Unnotched samples were strained at an approximate strain rate of 0. 01-inch per inch per minute up to about 2 percent deformation. The strain rate was then increased to about 0. 05-inch per inch per minute until failure. Notched specimens were loaded at a rate of 1000 psi net section stress per second. The test procedures followed those of References 2 and 3. Strain measurements were made on the unnotched specimens using the extensometer system described previously. RESULTS AND DISCUSSION Since each of the alloys used in this investigation was tested in two conditions of thermal and mechanical history the results obtained in the program for each of the materials will be presented and discussed in separate sections. Rene' 41 The properties of this alloy were evaluated in the annealed and aged condition and in the cold worked 35 percent and aged condition. Smooth and notched specimens (Kt>20) were tested at 800', 1000~ and 1200~F. The properties measured included creep strength, rupture strength and tensile strength as influenced by stressed exposure. 5

Annealed and Aged Condition The results of the stress-rupture time tests on smooth specimens are presented in Table II. The data show that there was very little effect of specimen orientation on properties at either 1000~ or 1200~F. These data are presented graphically in Figure 2. There was a pronounced tendency for the specimens to fracture at the pinholes or beneath the clamp-on collars used to hold the extensometer rods, The tendency for fracture at the pinholes was particularly pronounced at 12000F and suggests that Rene' 41 sheets in the annealed and aged condition might be sensitive to mild notches. If this is actually the case it is contrary to the general behavior of this type of alloy (Ref. 4), A sensitivity to mild notches has, however, been shown for materials of this type when tensile tested at elevated temperatures (Ref. 5). The tendency for fracture beneath the collars probably was caused by a compressive stress at this location which raised the effective stress on the specimen at the point beneath the clamp-on collars. The stress-rupture time curve (Figure 2) for smooth specimens at 1000~F had little slope. The 1000-hour rupture strength at this temperature was approximately 158, 000 psi as compared with a tensile strength at the same temperature of 178, 000 psio The smooth specimen rupture data at 12000F cannot be considered reliable because of the tendency of the specimens to fracture at the pinholes and beneath the extensometer collars, The results of the notched specimen tests are presented in Table 3. At 800~F the specimens survived exposure for 1000 hours at stresses as high as 145, 000 psi. This stress represents approximately 95 percent of the notch-tensile strength of the alloy at this temperature. A similar resistance to sharp edge-notches was not evident at 1000~ or 1200~F, as is shown in Figure 3. At 1000~F the sharp edge-notch specimens exhibited a relatively flat rupture curve out to approximately 300 hours, at which point the curve broke rather sharply downward. The 1000-hour notch strength at 10000F represents just over 50 percent of notched spec 6

imen tensile strength at this same temperature as compared with over 95 percent at 800 F. At 1200'F the properties are much lower than at 1000 Fo At 1200OF the scatter of the results is such that it is impossible to draw any meaningful curve through the data. Figure 4 shows a graph of minimum creep rate versus stress for the annealed Rene' 41 at 800', 1000~ and 1200~Fo The lines drawn through the data at each of the temperatures were approximately parallel to one another. As was the case for the smooth specimen rupture data, no differentiation could be made in the results due to specimen orientation. Data have been obtained which show the influence of stressed exposure on the room temperature tensile,properties of the alloy in the annealed condition. These data are presented in Table IV. Examination of the data shows that stressed exposures at temperatures of up to 12000F have little influence on subsequent room temperature tensile properties. The only exception to this statement might possibly be the transverse notched specimens exposed at 1200~Fo Two specimens exposed at this temperature for 1000 and 2000 hours under stresses of 40 and 60 ksi,respectively, showed notch strengths which were 23 and 34 ksi below that exhibited by the unexposed materialo Cold Reduced and Aged Condition The creep and stress-rupture results obtained from smooth specimens at 800', 1000~ and 1200~F are given in Table V. As was the case with the alloy in the annealed and aged condition, none of the creep-rupture specimens fractured at 800'F in times up to 2000 hours and at stresses of up to almost 99 percent of the ultimate tensile strength of the material at that temperatureo At 1000~F, although the stress-rupture time curves (Figure 5) were relatively flat, there was some stress dependency of the rupture time. At 1200'F this dependency was very evident, as is shown in the stress-rupture time curves of Figure 5. At 1000~F there appeared to be a significant difference in rupture time between longitudinal and 7

transverse specimen orientation. This difference may not be real, however, since the transverse specimens showed a particular affinity for fracturing beneath the extensometer collars. As was stated in the previous section, the specimens were subjected to a small compressive stress at the point of contact with the collars. This slight compressive stress may have acted to raise the effective stress on the specimen at this location, thereby causing premature failure. It should be remembered, however, that specimens taken from the sheet material in a longitudinal orientation were also subjected to this compressive force but did not show the same tendency for failure beneath the collars. The notched specimen results are tabulated in Table VI and are presented graphically in Figure 6. At 800~F, with one exception, the specimens either fractured on initial loading or survived exposure under stresses as high as 140 ksi for time periods of 1000 or 1200 hours. A transverse specimen did fail in 890 hours under a stress of 135 ksi at 800~F. A longitudinal specimen survived exposure for 1000 hours under a stress of 140 ksi at this same temperature, indicating that specimens taken in the longitudinal direction are somewhat stronger that those taken in the transverse direction. At 1000~ and 1200~F the longitudinal notched specimens gave significantly higher results than did the transverse specimens. At 1000~F there was a marked variability in the results. While the cause of this behavior has not been determined it is suggested that the rupture life of the notched specimen is limited by the ductility of the material. Table V shows that the rupture ductility of the smooth specimens in the longitudinal direction is considerably greater than that of the transverse specimens. There is little doubt that the apparent low ductility of the transverse smooth specimens is partly the result of the tendency of these specimens to fracture under the collars. Not all of the specimens fractured beneath the collars, however. If we discount those specimens which did break at this location it is still evident that the transverse specimens had lower rupture ductility than the longitudinal specimens. The suggestion that the variability of the notched specimen results as 8

well as the difference in the results as a function of specimen orientation was partially the result of the low rupture ductility of the alloy in the cold reduced condition is indirectly confirmed by the minimum creep rate data of Figure 7. These data do not show any significant influence of specimen orientation on the creep resistance of the material and therefore creep resistance, per se, is not the cause of either the scatter in the results or the variation in properties with specimen orientation. Table VII lists the results obtained in the study of the influence of stressed exposure on the room temperature tensile properties of cold worked Rene' 41. Both smooth and notched specimens exposed under stress at 650O, 800~, 1000' and 1200~F exhibited room temperature properties very similar to the unexposed alloy. The apparent lowering of tensile properties in the case of the longitudinal notched specimens was probably the result of material variability rather than any influence of stressed exposure. The results of a limited study designed to determine the influence of plastic strain introduced prior to stressed exposure on tensile properties are listed in Table VIII. After the specimens were strained between 0 and 3 percent at 10000F they were exposed for 1000 hours at 10000F under stresses from 40 to 80 ksi. Upon completion of the stressed exposure the specimens were tensile tested at either room temperature or 1000~F, The results of this study are shown in Figure 8. In this graph the ultimate tensile strength of the material is plotted as a function of the amount of plastic strain introduced prior to exposure. The ultimate tensile strength is shown to increase markedly with the amount of prior plastic strain. While it is not possible to completely separate the effects due to plastic strain from any which might result from varying exposure stress, it is highly likely that the plastic strain and not the exposure stress caused the pronounced increase in tensile strength. Figure 7 shows that the amount of creep caused by a stress of 80 ksi at 1000lF for 1000 hours would be negligible. Furthermore, the data presented in Table VII 9

showed stressed exposure to have very little influence on room temperature tensile properties. The most satisfactory explanation for the increase in ultimate tensile strength as a function of plastic strain is the occurrence of a straininduced secondary precipitation. The amount of such a precipitate should increase with increasing strain. This in turn would be related to the degree of increase in tensile strength. A strain induced precipitation would not only account for the smooth specimen results shown in Figure 8 but would also help ekplain.the notched specimen results. At 800~F the notched specimens withstood exposure without rupturing for times up to 2000 hours at stresses of 99 percent of the notch strength of the material. At 1000~ and 1200~F, however, the notched specimens failed in relatively short times at stresses as low as 30 percent of the notched specimen tensile strength. This suggests that creep is necessary before failure can occur. If the creep which takes place in this alloy at 1000~ and 1200~F causes a strain-induced precipitate to form then the precipitate could strengthen and coincidentally embrittle the alloy. The ductilities of the tensile specimens plastically strained prior to stressed exposure (Table 8) are significantly lower than those which were not strained. Since very little creep occurs at 800'F even at very high stresses the amount of the strain-induced precipitate formed would be very limited. This may well be the reason why the embrittlement did not take place at this temperature. As previously mentioned, anisotropy effects in the cold worked sheet material should also limit rupture ductility in certain specimen orientations. The combination of the strain-induced precipitate and specimen anisotropy should account for the low notched specimen results. The influence of the strain-induced precipitation should be more pronounced in notched specimens than in smooth specimens. This would result from the presence of the stress concentration which would effectively segregate most of the strain to the area of the root of the notch. The strain 10

induced precipitation would tend to embrittle the material at the root of the notch and thereby limit the notched specimen rupture life of the alloy. Waspaloy This alloy, like the Rene' 41, was studied in two conditions of treatment, the annealed and aged condition and the cold reduced 40 percent and aged condition. Annealed and Aged Condition Smooth specimen results are reported in Table IX for creep-rupture tests at 8000, 1000~ and 1200F. The general behavior of the smooth specimens was very similar to that exhibited by the Rene' 41 alloy. Specimens exposed at 800'F under stresses as high as 98 percent of the notched specimen tensile strength did not fail in times up to 1200 hours. At 1000~F the stress rupture time curve (Figure 9) was relatively flat and evidenced little influence of specimen orientation. At 1200~F the specimens tended to fail under the collars and at the pinholes. For this reason a reliable stress rupture time curve could not be established at this temperature. The notched specimens (results reported in Table X) also behaved in a manner similar to the annealed and aged Rene' 41 notched specimens. None of the notched specimens fractured in 1000 hours at 800~F except one which broke on initial loading. In the shorter time periods at 1000'F the notched specimen stress rupture time curve was relatively flat. The curve thereafter, however, exhibited a rather sharp break downward at approximately 600 hours (Figure 10). At 1200~F the results showed a significant amount of scatter. At this temperature insufficient numbers of tests were run to establish the limits of the scatter.band of the notched results. Figure 11 shows the minimum creep rates exhibited by the alloy as a function of stress. There does not appear to be any influence of specimen orientation on the creep rate. This conclusion, however, is based 11

on limited data. The results of a study of the influence of elevated temperature stressed exposure on the room temperature tensile properties of annealed and aged Waspaloy are presented in Table XI. These results, as did those for Rene' 41, show no significant influence of stressed exposure on subsequent room temperature tensile properties. Cold Reduced and Aged Condition The minimum creep rates and stress-rupture time data obtained from tests on smooth specimens at temperatures from 800~ to 12000F are tabulated in Table XII. The tests at 800~F did not rupture in times from 1000 to 1400 hours at stresses which were as high as the reported ultimate strength of the alloy in the condition (Ref. 1). Figure 12 shows the stressrupture time curves obtained from the smooth specimens at 10000 and 1200~F. At both temperatures the specimens tended to fracture underneath the clamp-on collars used to hold the extensometer bars. A number of tests were carried out in which the testing condition were duplicated, except that collars were not attached to the specimens. The results were rather startling in that no definite evidence was found to indicate that the collars had any influence on rupture life. There were just as many cases where specimens tested in the presence of collars ruptured in longer times than specimens without collars tested under identical conditions as there were cases where the reverse was true. The conclusion has to be reached that the influence of the collars on rupture life was minor compared with the inherent variability of the cold worked Waspaloy sheet material, even though rupture occurred where the collars were attached to the specimens. At 1000~F the stress-rupture properties of smooth specimens taken in the transverse direction were poorer than the properties exhibited by longitudinal specimens (Figure 12). This behavior was not evident at 1200 F. The inferior properties at 1000~F of the transverse specimens were probably due to anisotropy effects on rupture ductility. Why 12

this same behavior did not occur at 1200 F is not known. The results of the notched specimen tests at 10000 and 1200'F are reported in Table XIIIo Examination of these data, which are graphically presented in Figure 13, shows that the transverse notched specimen properties were inferior to the properties of the longitudinal specimens. This was true at both 10000 and 1200F and was probably due to anisotropy effects. While some scatter of the notched specimen properties existed, it was significantly less than was noted for the Rene' 41 sheet material. The creep data obtained from the smooth specimens are plotted in Figure 14. No difference in minimum creep data with specimen orientation was observed. The curve drawn through the 1200'F results had a greater slope than the curves drawn through the data obtained from the tests at 8000 or 1000'F, which were parallel to one another. Stressed exposure at temperatures from 6500 to 12000F had very little influence on the room temperature tensile strength of either notched or smooth specimens. These data are reported in Table XIV. The only exception to this statement might be the lo ngitudinal notched specimen exposed for 2800 hours at 1200'F under 40, 000 psi stress. The notch strength of this specimen at room temperature was only 150, 000 psi compared with 212, 000 psi for the unexposed alloy. A transverse specimen exposed at 1200 ZF, however, did not show any reduction in notch strength compared with the unexposed material. Table XV lists the results of a limited study of the influence of plastic strain on tensile properties. As was the case with the cold worked Rene' 41, plastic strain introduced prior to stressed exposure for 1000 hours at 1000'F caused the ultimate tensile strength of the material to be increased at both room temperature and 1000~F. These results are shown in Figure 15. As was noted previously for the Rene' 41 results, the increase in tensile strength was probably due to a straininduced precipitation. An interesting feature of these tests as well as the tests on the cold reduced Rene! 41 was that it was necessary in 13

several cases to exceed the reported ultimate strength of the material in order to introduce the desired amount of plastic strain into the specimens. In these cases the stress applied to the specimens was as much as 5 percent greater than tensile strength of the alloys. This again indicates that the straining acted to strengthen the alloys through a mechanism involving the formation of a strain induced precipitate. A limited number of rupture tests was conducted at 12000F under 100, 000 psi on specimens containing notches of varying sharpness. The results of these tests are reported in Table XVI. These results show that the rupture life falls off very rapidly with increasing notch acuity. On the average specimens with dull notches having a Kt = 1. 5 showed a marked drop in rupture time compared with smooth specimens. When the theoretical elastic stress concentration factor of the notched specimens exceeded 3 the rupture properties of the alloy were approximately as poor as observed in the presence of sharp notches having a Kt in excess of 20. These results were surprising since these types of alloys usually exhibit notch strengthening at low values of notch acuity (Ref. 4). Applicability of Results In the application of the results to the determination of the upper temperature os usefulness of Rene' 41 and Waspaloy in the supersonic transport several reference parameters were used. These reference parameters were as follows: 1. Stress for rupture in 50, 000 hours 2. Stress to produce a minimum creep rate of 0. 1 percent in 50, 000 hours 3. Minimum time for rupture of specimens containing the ASTM sharp edge-notch at a stress of 40, 000 psi. These reference parameters were selected on the basis of simplified design requirements for the supersonic transport. In the SST application the design stress for the superalloys is expected to be 40, 000 psi. The alloys must be able to withstand this stress for an operating life of 14

50, 000 hours without failing and without accumulating more than 0. 1 percent creep. In theory the ASTM sharp edge-notch simulates a cracko The superalloys must be able to withstand the presence of cracks under the design stress for prolonged periods of time at the upper use temperature. From the proceeding considerations the three above-listed reference parameters were selected. For a material to be serviceable at the upper temperature it would have to have a stress for ruptureo in 50, 000 hours of at least 40, 000 psi if rupture strength limits the upper use temperature. If the controlling function is creep resistance then the upper temperature of usefulness would be that temperature where a stress of 40, 000 psi causes an accumulation of approximately 0t 1 percent in 50, 000 hours. A minimum creep rate of 0. 000001 percent per hour should approximate a total accumulation of about 0. 1 percent plastic strain in 50, 000 hours. This approximation has been made in order to allow for any primary creep which might occur in the structure. Finally, if the factor which controls the peak temperature is the resistance of the material to the presence of cracks then the alloys should be able to withstand these cracks for prolonged time periods under a stress of 40, 000 psi. The length of these prolonged periods has not been determined, however, they should be sufficiently long to allow for the detection of cracks. For the purpose of this report this time period has been arbitrarily selected at 10,000 hours. Stress for Rupture in 50, 000 Hours Linear extrapolations of the log stress-log rupture time curves (Figures 2, 5, 9, 12) were made to arrive at the stress for rupture in 50, 000 hours for smooth specimens of both alloys in each condition of prior treatment and in each orientation. These results are presented in Table XVIIo Extrapolations of the data obtained from both alloys in the annealed and aged conditions at 1200F could not be justified because of the scatter of the results and the lack of long-time data. 15

Examination of the data shown in Table XVII shows that both alloys in the cold worked condition are suitable for service up to at least 1200~F from the standpoint of rupture strength. The cold reduced Rene' 41 gave appreciably higher rupture strength than did the Waspaloy. Both alloys in their annealed and aged conditions exhibited strengths which would ensure more than adequate rupture life at temperatures of at least 1000 F. It is likely that the alloys in the annealed and aged condition could be used at temperatures somewhat above 1000~F. Creep Resistance In Table XVIII the stresses to produce a minimum creep rate of 0. 000001 percent per hour at 800~, 1000~ and 1200~F have been tabulated. This minimum creep rate together with the deformation on loading and primary creep should correspond to an approximate accumulation of 0. 1 percent plastic strain in 50, 000 hours. The data presented in Table XVIII were obtained by linear extrapolations of the log stress-log minimum creep rate curves of Figures 4, 7, 11 and 14. Examination of the data shows that both alloys in both conditions of prior treatment exhibit stresses to produce a minimum creep rate of 0. 000001 percent per hour greater than 40, 000 psi at temperatures of up to and including 1200~F. Based on this reference parameter the alloys in the conditions in which they were tested in this program are suitable for service in the supersonic transport at temperatures of up to at least 1200~F. Notch Resistance Due to the wide scatter of the results obtained from the specimens containing the ASTM sharp edge-notch it was impossible in some cases to extrapolate the data to determine the time for rupture of these specimens under a stress of 40, 000 psi. Estimates of the minimum time for rupture of the notched specimens under this stress, however, have been 16

made, These estimates were based on the observed width of the scatter band of the data and on the maximum observed slope of the log stresslog rupture time curves. These estimated times are tabulated in Table XIX. If these estimates are approximately correct then neither the Rene' 41 nor the Waspaloy in the conditions in which they were tested in this investigation is suitable for service in the supersonic transport at 1000XF or above. The results obtained from the alloys at 800 F, however, indicate satisfactory properties at this temperature. At this temperature only two specimens which survived initial loading fractured during exposure in times up to 2000 hours. These two specimens were loaded to stress levels well above 100, 000 psi, Although the reference parameters of rupture strength, creep resistance and notch resistance in tensile tests before and after exposure indicate adequate properties for the SST, the upper temperature of usefulness of the materials tested was limited to between 800~ and 1000~F by sensitivity to cracks and stress concentrations under creep conditions. Since materials operating in the area of the engines of the SST will be required to withstand temperatures up to approximately 1200~F for prolonged periods of time, the materials tested would be unsatisfactory for application at higher temperatures. Additional research should be carried out to determine if this sensitivity to notches under creep conditions is typical of the Rene' 41 and Waspaloy alloys. This research should include a study of the effects of other heat treatments. In particular, it should be established whether or not the notch sensitivity could be eliminated by heat treatments leading to lower strength levels in the alloys. Certainly the research should look for alloys which will not be subject to this weakness. The other materials proposed for the SST, titanium alloys and precipitation hardened stainless steels, probably would not maintain sufficient creep resistance for application at these temperatures. If the results obtained in this investigation are typical of Rene' 17

41 or Waspaloy it will be necessary to find alloys and/or heat treatments which will have or give satisfactory strength levels with suitable notched specimen strength and stability during and after exposure. CONCLUSIONS An investigation of the tensile, creep and rupture properties of Rene' 41 and Waspaloy sheet materials at temperatures from 800~ to 1200~F has been carried out. Both alloys were tested in the annealed and aged condition as well as in the cold reduced and aged condition. The cold working of these alloys resulted in much higher strengths than could have been obtained by heat treatment alone. From the results of this study the following conclusions can be drawn: 1. In the conditions in which these alloys were tested their upper temperature of usefulness in the proposed supersonic transport is limited by the poor resistance of the alloys to the presence of cracks and stress concentrations when they are exposed to temperatures where significant amounts of creep can occur. In this investigation cracks were simulated in specimens by ASTM sharp edge-notches. 2. The creep resistance and rupture strength of both alloys in the cold worked and aged condition were above the expected design stress of 40, 000 psi at temperatures up to 1200~F. 3. The creep resistance as measured by the stress required to produce a minimum creep rate of 0. 000001%/hour of both Rene' 41 and Waspaloy in their annealed and aged conditions was in excess of 40, 000 psi at temperatures up to 1200~F. 4. The stress required for rupture in 50, 000 hours of the alloys in the annealed and aged condition was in excess of 100, 00, 0 psi at 1000~F. 5. The resistance of the alloys during stressed exposure in both conditions of prior treatment to sharp edge-riotches and stress concentrations was satisfactory at 800~F but not at 10000F or 1200~F. 18

6. Tests at 1200'F on specimens of Waspaloy in the annealed and aged condition showed that mild notches (Kt = 3. 1 or above) were as detrimental to the properties of the alloy as sharp edge-notches (Kt>20)o Specimens containing notches with theoretical elastic stress concentration factors of 1. 5 and 2. 1 had stress-rupture time properties at 1200'F much poorer than exhibited by smooth specimens. 7. With very few exceptions stressed exposure for time periods up to 4000 hours at temperatures from 6500 to 1200'F had no effect on the subsequent room temperature tensile properties of either the Waspaloy or the Rene' 41 sheet materials. 8. If the use of superalloys in certain sections of the SST requires that these materials withstand prolonged exposure to temperatures of 1000~F or above, then Rene' 41 and Waspaloy of the quality and/or in the conditions of prior treatment in which they were tested in this investigation are not suitable for the application. The conclusions expressed are only intended to apply to Rene' 41 and Waspaloy in the conditions in which they were tested in this investigation. There may well be conditions of melting, processing and/or heat treatment which when applied to these alloys would ensure their satisfactory performance in the supersonic transport. Conversely, the stress-rupture time characteristics of other alloys being considered for use in the SST have not to the authors' knowledge been evaluated with specimens containing cracks or sharp edge-notches, the conditions shown in this investigation to limit the usefulness of Rene' 41 and Waspaloy to temperatures below 1000~F. It is possible that these alloys may also exhibit a sensitivity to the presence of notches and stress concentrations when exposed for prolonged time periods under creep conditions. 19

REFERENCES 1. Raring, R. H., Freeman, J. W., Schultz, J. W. and Voorhees, H. R.: Progress Report of the NASA Special Committee on Materials Research for Supersonic Transports. NASA Technical Note D-1798, May 1963. 2. Special ASTM Committee; Fracture Testing of High-Strength Sheet Materials, Chapter I, ASTM Bulletin, January 1960, pp. 29-40; Chapter II, ASTM Bulletin, February 1960, pp. 18-28. 3. Manning, C. R., Jr. and Heimerl, C. J.: An Evaluation of Some Current Practices for ShortTime Elevated Temperature Tensile Tests of Metals. Langley Research Center, Langley Field, Virginia, NASA TN-D-420, September 1950. 4. Voorhees, H. R. and Freeman, J. W.: Notch Sensitivity of High-Temperature Alloys. WADC Technical Report 59-470, March 1960. 5. Schultz, J. W., Cullen, T. M. and Freeman, J. W.: Influence of Notch Acuity on the Notch Strength of Rene' 41, Waspaloy and D979. NASACR-50178, March 1963. 20

TABLE I Chemical Compositions of Experimental Materials Alloy Heat C Si Mn Cr Ni Co Mo Ti Al Fe S B Zr Number Rene'41 R-217.09.07.06 18,97 Bal, 11.20 9,75 3.20 1,50 <.30.006.0045 Rene'41 R-216.10,06.06 18.48 Bal, 10.43 9,37 3, 19 1,42 2,20,007.0047 Waspaloy B-119.08.07,04 19.63 Bal, 13.49 4.26 2,99 1.40 2,30.007.0048.03 N 1-~a

TABLE II Summary of test results from smooth specimens of Rene' 41 - annealed at 1975~F, W. Q., and aged for 16 hours at 1400~F Specimen Code Directionality Temp. (~F) Stress (Ksi) Rupture Life (hrs) Elong. Minimum (%) Creep Rate (%/h ) RLS 144 RTS120 RLS140 RLS23 RLS141 RTS117 RTS 113 RTS 112 RTS 11 RTS116 RTS110 RTS114 RTS115 RTS118 RTS119 RTS122 RLS 143 Long. Trans. Long. It ft Trans. f! f! if f! If Trans. If fo ft Long. 800 800 1000 it If 1000 if If It 1200 If 11 if it If 1200 175 0.000063 0. 000116 180 170 165 160 170 165 165 150 1 50 130 165 145 135 125 125 140 56.3 283.4 648. 2 69. 0 163. 1 193.7 601.8c 645.4 >iooob >1000 Od 1.9 10. Oe 42.6C 20. 9 14. 9e 20. 8 11. 5 0.0118 0. 00062 10.2 12.5 10. 7 5.2 6.5 0.8 11.0 2.7 3.0 1.25 0. 0104 0. 00024 0.00034 0.0000134 0. 053 0. 0095 1.5 a - Interrupted after 2000 hours b - Interrupted after 1000 hours c - Broke at Pin Hole d - Broke on loading e - Fractured under Collar 22

TABLE III Summary of test results from notched specimens of Rene' 41 - annealed at 1975~F, W. Q., and aged for 16 hours at 1400~F Specimen Code Directionality Temperature (~F) Stress, ksi Rupture Time (hrs) RLN137 RLN160 RTN108 RTN107 RLN133 RLN134 RLN26 RLN27 RLN28 RTN101 RTN102 RTN19 RTN16 RTN15 RLN130 RLN131 RLN135 RLN138 RLN132 RLN139 RTN104 RTN105 RTN103 RTN106 RTN100 Longitudinal if Transverse If Longitudinal If il If il Transverse II Il Longitudinal II II 11 800 1 800 1000 it il 1000 If 1000 if fl 1200 If if f! If 1200 I I Il I fI II nr nr nr 145 140 145 135 120 110 100 80 60 120 110 100 80 60 100 80 70 65 60 55 100 80 80 70 60 cOO^a >100lO,> 1000a >1000a >1000a 315. 3 149. 0 446. 9 788. 0 2903.0 71. 0 230. 6 447. 3 856. 3 1831.5 20. 0 73.7 32.4 21. 3 149. 4 23. 0 20. 0 14. 8 12.4 24. 9 >2000b Transverse If i i t a - Interrupted after 1000 hours b - Interrupted after 2000 hours 23

TABLE IV Tensile Properties at Room Temperature of Interrupted Specimens of Rene' 41 in the Annealed and Aged Condition Exposure Conditions Tensile Properties Temp. OF Time Stress hrs. ksi Ultimate Strength, ksi 0. 2% Offset Yield Strength, ksi Elong. %o Longitudinal Smooth Specimens None 650 800 1000 1200 1000 1000 1000 1000 40 40 40 40 204 196 187 203 213 154 155 156 157 167 22 16 11 24 22 Transverse Smooth Specimens None 650 800 1000 1000 1200 1000 1000 1000 1000 1000 40 40 40 130 40 204 195 201 201 204 206 154 152 154 23 13 25 19 13 19 174 161 Longitudinal Notched Specimens None 650 800 800 1000 1000 1200 1000 1000 1000 1000 1000 1000 40 40 145 40 40 40 172 170 169 158 166 176a 170 Transverse Notched Specimens None 650 800 800 800 1000 1000 1200 1200 1000 1000 1000 1000 1000 1000 1000 2000 40 40 135 145 40 40 40 60 171 162 169 164 161 159 169a 148 137 a - Notch machined after exposure 24

TABLE V Summary of test results from smooth specimens of Rene' 41 - Cold Worked 35 percent and aged for 2 hours at 1500~F Specimen Code R2LS53 R2LS28 R2TS51 R2TS48 R2LS50 R2LS48 R2LS43 R2LS42 R2LS51 R2LS40 R2LS43 Directionality Long. if Trans. ft Long. If I If If fi Kf 800 800 1000 if If t If if it 218 215 210 205 215 210 210 200 195 185 150 >2000a >1000 >1400C >1000b od 240. 0 485. 7 599. 2e 1951. 3e Temp. Stress Rupture Life ~F ksi Hours Elong. Minimum %o Creep Rate _%/hr. 0. 00013 0. 00005 0. 00008 0. 00004 5. 3 3. 0 4. 5 4. 5 3. 5 0.0151 0. 00863 0. 00575 0. 00295 0. 00095 0. 00008 R2TS37 R2TS33 R2TS42 R2TS39 R2TS32 R2TS40 R2TS33 R2LS44 R2LS45 R2LS52 R2LS46 R2LS41 R2LS49 R2TS35 R2TS34 R2TS43 R2TS36 R2TS39 R2TS41 Trans. it if if Long. if if if it Trans. if If it If 1000 If I I I 1200 if 11 11 if If 1200 if 11 it It fl ffl 200 200 190 180 165 150 150 200 185 150 130 115 105 185 165 150 130 115 105 81. 1 156. Oe 240. 5e 451.9e >4000f 0. 5 1. 1 31. 1 129. 3 389. 1 924. 7 1.4e 2 5e 8. 8 74. 8 372.4 672. 1e 2. 5 1.5 1.0 1.0 18. 5 18. 2 11. 5 4. 5 9. 5 10. 3 4. 5 2. 0 2. 0 2. 5 4. 5 1. 5 0. 0136 0.0071 0. 00414 0. 00079 0.000176 0.000032 0. 00005 10. 0 5. 0 0.0152 0. 00556 0.00181 2.0 0.40 0. 0240 0. 00390 0. 00172 a - Interrupted after 2000 hours b - Interrupted after 1000 hours c - Interrupted after 1400 hours d - Broke on loading e - Fractured under collar f - Interrupted after 4000 hours 25

TABLE VI Summary of test results from notched specimens of Rene' 41 - Cold Worked 35 percent and aged for 2 hours at 1500~F Specimen Code R2LN67 R2LN69 Orientation Temp. ~F 800 I Stress, ksi Rupture Life Hours >1000a >1200b Long. 11 140 130 R2TN111 R2TN113 R2TN114 R2TN115 R2LN58 R2LN43 R2LN59 R2LN41 R2LN64 R2LN57 R2LN60 R2LN40 R2LN61 R2LN63 R2LN39 Trans. if if Long. If l It I fI II I II f I I 800 if If 1000 If It il II il If 11 11 f I 145 140 135 130 115 115 100 100 90 90 80 80 75 70 60 oc oc 890. 7 >1200 37.8 79. 5 237. 3 143.6 37. 5 294.8 2369.2 442. 2 >2000d >2400e >3000f R2TN37 R2TN32 R2TN34 R2TN101 R2TN105 R2TN102 R2TN33 R2TN103 R2TN107 R2TN112 R2TN38 R2TN12 R2TN17 R2TN13 R2TN16 R2TN18 Trans if if it if 11 I if 11 11 If II ol it 1 1 1000 I If I 1 I I If I I I f! M I I I I 115 100 100 90 90 80 80 70 70 65 60 40 40 40 40 40 24. 3 53.8 105. 4 66. 3 190. 4 144. 8 188 9 514.8 192. 2 691 0 >3342. 4 743. 3 941.9 >1000a >1000a >1000a continued 26

TABLE VI concluded Specimen Code R2LN66 RZLN62 R2LN42 R2LN65 Orientation Long. if if l l l l Temp. "F 1200 If If I Stress, ksi 100 90 80 60 Rupture Life Hours 6: 4 2.9 881.9 >2000 R2TN110 R2TN104 R2TN109 R2TN108 R2TN106 Trans if If If 1200 It if l l l l 80 70 60 50 45 1.4 6.3 83. 8 211.9 >2000d I a - Discontinued after b - Discontinued after c - Broke on loading d - Discontinued after e - Discontinued after f - Discontinued after g - Discontinued after 1000 hours 1200hours 2000 hours 2400 hours 3000 hours 3342 hours 27

TABLE VII Tensile Properties at Room Temperature of Interrupted Specimens of Rene' 41 in the Cold Reduced and Aged Condition Exposure Conditions Tensile Properties Temp. ~F Time hrs. Stress ksi Ultimate Strength, ksi 0. 2% Offset Yield Strength, ksi Elong. %o Longitudinal Smooth Specimens None 650 800 1000 1000 1000 1000 40 215 40 249 246 271a 251 230 230 8 9 2 7 237 Transverse Smooth Specimens None 650 800 800 1000 1000 1000 1000 1000 1000 4000 40 205 210 40 150 237 242 246 268a 240 271 216 222 7 7 5 1.5 6 2 221 261 Longitudinal Notched Specimens None 650 800 1000 1000 1000 1000 1200 1000 1000 1000 3000 2400 2000 2000 40 140 40 60 70 75 60 196 182 173 147 156 164 180 164 Transverse Notched Specimens None,650 1000 1200 1000 1000 2000 40 40 45 182 190 161 120 a - Specimen fractured under collar 28

TABLE VIII Influence of Plastic Strain and Stressed Exposure at 1000~F for 1000 hours on the Tensile Strength of Rene' 41 - Cold Worked 35 percent and aged for 2 hours at 1500~F Specimen Code Direction ality Exposure Stress, ksi Plastic Strain, % Max. Temp, of Applied Tensile Stress Test psi ~F R2LSa R2LS R2LS38 R2LS39 R2TSa R2TS R2TS19 R2TS18 R2LSa R2LS R2LS36 R2LS35 R2TSa R2TS R2TS30 R2TS20 Long. 11 11 I Trans, II I! Long, II Trans, It i 0 40 60 80 0 40 60 80 0 40 60 80 0 40 60 80 0 0 1.0 2. 0 0 0 1. 2 2.2 0 0 2. 7 1. 2 0 0 2. 0 2, 0 210 914 229,537 206,879 229,787 208, 160 224, 194 214,678 210 914 R, T. It II It 11 R., II 11 I1 1000 II I 11000 IT II Ultimate Tensile Strength ksi 249 251' 275 289 237 240 260 265 221 227 239 5 231 218 219 230 5 233 0.2% Offset Yield Strength, ksi 230 237 272 -b 8. 0 7,0 1, 5 1, 5 Elong - ation % 216 221 _b 265 201 206 234 -b 194 193 228 219 7. 0 6. 0 3, 0 1, 0 3. 8 3. 0 1. 5 1. 5, 0 3, 5 2. 5 1. 2 a - specimen not exposed b - yield strength determination could not be made

TABLE IX Summary of test results from smooth specimens of Waspaloy - annealed and aged for 16 hours at 1400~F Specimen Code Directionality Temp. OF Stress Rupture Elong ksi Time firs) % Minimum Creep Rate %/hr. WLS 17 WTS133 Long. Trans. 800 800 155 0. 0005 160 0. 00008 WLS9 WLS 11 WLS115 WLS10 WLS110 WTS17 WTS10 WTS1 34 WTS9 WLS1 12 WLS 113 WLS 114 WLS1 16 WLS1 18 WTS18 WTS19 Long. fi It ft Trans it if Long. ft ft Trans. 11 1000 t If It I I 1000 t ft 1200 it Ift ft fl 1200 lf 145 135 135 125 105 150 145 135 125 140 120 100 100 100 140 120 157.3 420. 7 577.4 2 592. 4 >1000b 227.4 181. 3 >2000 2916. 8 1.4d 14. 5 127e 40. 1d 40. le 1.4 19. 5d 11.0 7. 3 7. 0 4. 0 0. 3 8. 5 12. 0 3. 9 2. 0 0. 5 1. 5 0. 00357 0. 0007 0. 00061 0. 0000216 (c) 0. 0042 0. 00002 0.0000345 0.06 0.0017 0.00213 6. 5 2. 0 a - Interrupted after 1200 hours b - Interrupted after 1000 hours c - No measurable creep d - Fractured under Collar e - Broke at pin:hole 30

TABLE X Summary of test results from notched specimens of Waspaloy - annealed and aged for 16 hours at 1400~F Specimen Code WLN108 WLN106 WLN105 WTN129 WTN131 WTN128 WLN101 WLN14 WLN102 WLN13 WTN124 WTN16 WTN125 WTN14 WLN100 WLN103 WLN107 WLN104 WTN123 WTN126 WTN130 WTN127 Directionality Long., I if Trans. It Long. if It f Trans. if If Long, it If Trans. if If;f Temp. OF 800 fl 800 11 1000 it Ii 1000 II if 1200 it it if 1200 I1 it if n 12 Stress, ksi Rupture Time hours 135 130 125 135 130 125 115 100 80 60 Oa >1000b >1000b >1000b >1200C >1000 Oa 895. 1 1039. 0 2637. 0 301. 3 383. 6 >2000d 2128.2 115 100 80 60 80 60 55 50 22. 4 149. 4 19. 5 980. 3 80 60 55 50 21.4 117.7 28. 6 883. 9 a - Broke on loading b - Interrupted after 1000 hours c - Interrupted after 1200 hours d - Interrupted after 2000 hours, specimen cracked through about 20 percent of its area. 31

TABLE XI Tensile Properties at Room Temperature of Interrupted Specimens of Waspaloy in the Annealed and Aged Condition Exposure Conditions Tensile Properties Temp. ~F Time hours Stress ksi Ultimate Strength, ksi 0. 2% Offset Yield Strength ksi Elong. %o Longitudinal Smooth Specimens None 650 1000 1000 1000 1000 1000 40 40 105 191 186 192 200 139 135 144 149 31 31 31 25 Transverse Smooth Specimens None 650 1000 1000 1000 40 40 190 184 187 135 132 137 31 31 30 Longitudinal Notched Specimens None 650 800 800 1000 1000 1000 1000 1000 40 125 130 40 154 161 157 155 159 Transverse Notched Specimens None 650 800 800 1000 1000 1000 1000 1000 40 125 135 40 151 163 156 159 159 32

TABLE XII Summary of test Waspaloy - Cold results from smooth specimens of worked 40 percent and aged for 2 hours at 1500~F Specimen Code Directionality Temp. OF Stress ksi Rupture Life hours Elong. % Minimum Creep Rate %/hr. W3LS103 W3LS47 Long. If 800 it 204 200 >10ooo00a >1400b 0. 00012 0. 00011 W3TS40 W3TS37 W3LS25 W3LS3 1 W3LS45 W3LS41 W3LS28 W3LS33 W3LS46 W3LS32 Trans. I! Long. II 11 If If II if 800 II il 1000 II If II it 11 II l l l l rr 197 195 195 195 185 180 165 165 160 150 > 1300C >1000a 43.2 131.7d 252. 5 57. 5d 968. 0 727. 4d 1301.4d 9. 5 3. 5 3. 5 1.0 1.7 1.7 1.8 0.000086 0.000063 0. 1 0. 0204 0.0093 0. 005 0.00111 0. 0001055 0.0005 W3TS24 W3TS18 W3TS35 W3TS21 W3TS29 W3LS34 W3LS42 W3LS35 W3LS43 W3LS36 W3LS44 W3LS40 W3LS39 Trans. If it if it Long. 11 If If Il Ii II 1000 I II I IfI 1200 It If If If I 190 190 170 165 150 140 140 120 120 100 100 90 75 17. 3 104. 6 266.2 927. 2d 11. 4d 8. 8e 32. 7d 72. le 79.4d 394.6e 954.6d >1700f 5. 5 2. 5 1.5 1. 0 4. 0 4. O 2.0 3. 3 0. 5 2. 5 2.0 0.0204 0. 138 0.0074 0.00091 0. 000132 0. 305 0.0357 0.0021 0. 0009 0.000135 W3TS30 W3TS31 W3TS33 W3TS32 W3TS34 W3TS102 W3TS36 W3TS20 Trans. II If 11 If If if If 1200 If It If It if 11 li 11 140 120 120 100 100 90 90 75 8. 9 79. 7d 33. 8e 378.3d 276. 0e 345.2d 554. 1 1117. 2d 2. 5 2. 0 2. 5 1.5 1.5 1.0 1.5g 2. 3 0.21 0. 0125 0.00133 0.000715 0. 000192 a - Interrupted after 1000 hours b - Interrupted after 1400 hours c - Interrupted after 1300 hours d - Fractured under collar e - Test run without collars f - Interrupted after 1700 hours g - Fractured at fillet 33

TABLE XIII Summary of test results from notched specimens of Waspaloy - Cold worked 40 percent and aged for 2 hours at 1500~F Specimen Code Directionality Temperature ~F Stress, ksi Rupture Life hours W3LN120 W3LN50 W3LN49 W3LN119 W3TN61 W3TN43 W3TN62 W3TN42 W3LN33 W3LN126 W3LN38 W2LN125 W3LN118 W3LN39 W3TN34 W3TN50 W3TN41 W3TN49 W3TN40 W3TN36 W3LN36 W3LN115 W3LN35 W3LN116 W3LN117 W3TN47 W3TN44 W3TN37 W3TN38 W3TN39 Long. II if Trans. If r 11 Long. fl I 1.1 it fl II Trans. II II fl 11I Long. II II 11 ii Trans. (i It It 800 II I It 800 ii If 1000 It 11 II If II 11 100 II fl Is 11 if it 1200 Ii it if 1i 155 155 150 140 160 155 150 140 100 90 80 75 70 60 100 80 70 60 55 50 100 80 60 50 40 80 80 60 40 30 Oa >1200b >1000C >1000c oa >1000c Oa 752.0 134.9 150. 5 436.6 481.7 448.2 >3150d 14.1 40.6 173. 7 101.6 103.6 >435.6e 11.5 80.5 181.8 >3600f >2800g 1.3 1.6 4.4 264. 5 >2000h a - Broke on loading b - Interrupted after 1200 hours c - Interrupted after1000 hours d - Interrupted after 3150 hours Fuse blown, test discontinued Interrupted after 3600 hours Interrupted after 2800 hours Interrupted after 2000 hours 34

TABLE XIV Tensile Properties at Room Temperature of Interrupted Specimens of Waspaloy in the Cold Reduced and Aged Condition Exposure Conditions Tensile Properties Temp. "F Time Stress hours ksi Ultimate Strength, ksi 0. 2% Offset Yield Strength, ksi Elong. % Longitudinal Smooth Specimens None 650 800 800 1000 1200 1000 1400 1000 1000 1700 40 200 204 40 75 237 227 250a 244 234 246 216 206 244 233 215 224 9 10 2 4 9 5 Transverse Smooth Specimens None 650 800 800 1000 1000 1000 1300 1000 40 195 197 40 232 224 235 237 228 206 201 11 9 5 4 9 237 208 Longitudinal Notched Specimens None 650 800 800 1000 1000 1200 1000 1000 1000 1000 3150 2800 40 140 150 40 60 40 212 196 207 173 193 195 150 Transverse Notched Specimens None 650 800 1000 1200 1000 1000 1000 2000 40 155 40 30 201 196 179 186 186 a - Specimen fractured under collar 35

TABLE XV Influence of Plastic Strain and Stressed Exposure at 1000~F for 1000 hours on the Tensile Strength of Waspaloy - Cold Worked 40 percent and aged for 2 hours at 1500~F Specimen Code Directionality Exposure Stress, ksi Plastic Strain, % Max. Temp. of Applied Tensile Stress Test psi ~F W 3LSa W3LS W 3LS29 W 3LS23 w^ cysl W3TSa W3TS W3TS19 W3TS25 W3TS26 W3TS23 W3LS a W 3LS W 3LS26 W 3LS24 W 3LS22 Long. 11, It It 1I Trans. II,r It it Long. II 11 l l 0 40 60 80 0 40 60 60 60 80 0 40 60 80 100 0 0 2. 25 1. 5 0 0 1., 1. 75 2. 0 1. 25 0 0 1.25 2. 5 1. 7 213,042 202,027 186,852 198,259 189,994 185,892 201,000 205,220 202,408 R. T, It R. R. T. II It it 1000 II II I I, Ultimate Tensile Strength ksi 237 234 247 248 232 228 233 240 242 232 204 213 216 223 224 216 215 244 244 206 208 230 240 242 225 177 190 205 218 0. 2% Offset Yield Strength, ksi Elong - ation, % 9. 0 9. 0 1. 5 4. 5 11.0 9. 0 8. 0 4. 0 5. 5 4.2 4. 5 3. 5 2. 0 1, 7 2,25 a - Specimen not exposed

Spec Cc W3] W3] 'tiT 2 1 TABLE XVI Influence of Notch Acuity on the Rupture Properties of Waspaloy in the Cold Worked and Aged Condition limen Notch Acuity Stress Temperature Ru )de Kt psi OF Tir LS44 1.0 100,000 1200 3 LN64 1.5 1 1 rT NT/ 2 1 r I1 4 VW 351JINO W3LN59 W3LN58 W3LN60 W3LN61 W3LN56 W3LN57 W3LN54 W3LN36 W3LN36 1. D 2. 1 2. 1 3. 1 3. 1 5. 9 5, 9 9 4 9. 4 >20 I I I 11 1 ipture ne (hrs) q94.6 30. 4.04, 2 26.9 41.0 20. 7 16.4 10. 9 5. 2 12.0 1.4 11.5 I! II I I 11 II II I I II tI II 37

TABLE XVII Stress for Rupture in 50, 000 Hours 1000~F 1200~F Rene' 41 cold reduced longitudinal transverse 152, 000 psi 136, 000 psi 77, 000 psi 77,000 psi annealed longitudinal transverse 144, 000 psi 118,000 psi Waspaloy cold reduced longitudinal transverse 125, 000 psi 118,000 psi 52, 000 psi 52, 000 psi annealed longitudinal transverse 110,000 psi 110,000 psi 38

TABLE XVIII Stress for a Minimum Creep Rate of 0. 000001%/hr. 800 F 1000~F 1200~F Rene' 41 cold reduced annealed 180, 000 psi 150, 000 psi 118, 000 psi 120, 000 psi 68, 000 psi 68, 000 psi Waspaloy cold reduced annealed 164, 000 psi 124, 000 psi 112, 000 psi 47, 000 psi 66,000 psi 39

TABLE XIX Estimated Minimum Time for Rupture of Notched Specimens under a Net Section Stress of 40, 000 psi 1000~F 1200~F Rene' 41 cold reduced longitudinal transverse 12,000 hrs. 700 hrs. 6000 hrs. 60 hrs. annealed longitudinal transverse 5,500 hrs. 5,500 hrs. 35 hrs. 28 hrs. Waspaloy cold reduced longitudinal transverse 9,500 hrs. 700 hrs. 4000 hrs. 100 hrs. annealed longitudinal transverse 6,000 hrs. 6,000 hrs. 120 hrs. 120 hrs. 40

la. t 7 0,, I 50 _ Rad. 0 38 L 1.83. 2.0, 1.83 7, 0 Smooth (unnotched specimen (Kt = 1. 0). NOTCH RADII 0.250, 0.100, 0.040,0.010, 600 and 0. 0036, I._- I 1 [~sf~ k./.i..o o i.6 625 k - o. 050- - "/'JX~ o. — > I0.8,Rad. 03 0. 88 1. 13 _, 1. 0 1 00, 1 13 6.0 lb. Notched specimen for Kt = 1.5, 2. 1, 3. 1, 8. 6 and 9. 4. NOTCH RADIUS <0. 0007 _ Rad. 0.38 0.88 1.13 1.00 1 1.00 1.13 6. 0 Ic. ASTM sharp edge-notched specimen (Kt >20) Figure 1. Types of Test Specimens (All dimensions in inches) I 41

0n Q) k u) a h *4> Uw 800 - 600 400 Tensile Results 200 Qn0 1200~F 1000*F 100 80 ~~~~60 t | Longitudinal Transverse Solid points ine'cate specimens -_~~~~~~~~~~~~~~~~ ~~~~~~which fractured t pin holes or 40 10000F 0 0 beneath collars. 1200~F A V 20 10 _ I i I i t I I I N 0. I 1. 0 10 100 1000 10.000 Rupture Time, Hours Figure 2, Stress versus rupture time data obtained from smooth specimens of Rene' 41 in the annealed and aged condition at 1000~ and 1200~F.

oC o 0) 0) 0 0 o c 0 0 -, - C a; o v, c c0 o E o ~ _ Q. u 0, M U, h U I j ~'U O o E o K n i 'O (U o s O ^ C Qo C; C n O, kU) 3 h QC > (0 u U) c c nl U: Q,4 vli 0 ^ o 0 0 0 0 0 0 0 0 00 s0 ' r TSm 'SSaJlS 43

800 600 400 200 U) f1~ or 100 80 60 __.____________________.-_ ___1D-0- 0 1200~F 100 0 Longitudinal specimens o Transverse specimens! I I I I I I I I I I I II I, I~ I I ] ' J' I I I i 1 1 I I l I I [ I t f [1 40 20 10 0. 00001 0. 0 001 0. 001 0. 01 0. Minimum Creep Rate, Percent per Hour Figure 4. Stress versus minimum creep rate data for Rene' 41 in the annealed and aged condition at 800~. 1000~ and 1200~F. 1 1.0

800 600 400 200 __- 1 ' I I I I I I I....II I I I "'I" I I I I1" I I I I I Tensile Res ults, / lOOF 1000~? 1200IF * -_ ----------— O V -VA-~= O~ ~ ~ TA Un 0) vl.,, (n u V) 100 80 60 Longitudinal Transverse 1000~F 0 0 1200~F A V Solid points indicate specimens which fractured at pin holes or beneath collars, 40 20 - I I I I I L 1 I I I I I I I I 0. 1 1. 0 10 100 1000 10.000 Rupture Time, Hours Figure 5, Stress versus rupture time results obtained from smooth specimens of Rene' 41 in the cold worked and aged condition at 1000~ and 1200~F.

~(A a) 0} 4) u!n 800 600 400 200 Tensile Results 1000F - 00F - / i, Longitudinal Longitudinal ~ a ---- ---- -Transverse Longitudinal Transverse V V~-'' —1J000~F - Transverse 40 l | 1000~F 0 0 1200~F - Transverse 1200~F A V 20 0. 1 1.0 10 100 100 Rupture Time, Hours Figure 6. Stress versus rupture time data obtained from notched specimens of Rene' 41 in the cold worked and aged condition at 1000~ and 1200~F. D0 10. 000

600 400 2 00 100 a 80 n 60 40 0.00001 0 Longitudinal specimens 0 Transverse specimens 10 n In 1.0 0. 001 0 0010.01 Minimum Creep Rate. Percent per Hour Figure 7. Stress versus minimum creep rate for Rene' 41 in the cold worked and aged condition at 800~. 1000~ and 1200~F,

320 300 C U) 4-> r, C^) u - ~r-4 rr> 51 280 260 240 0 Lor gitudinal specimens O Tr nsverse spEcimens |O/ Room /: Temperatu e MOM~ ~ - ^\\ 1000~F 0- - - O 220 200 unexposed 0 1 2 3 4 Plastic Strain, Percent Figure 8. Influence of plastic strain introduced prior to stressed exposure on the ultimate tensile strength of Rene' 41 in the cold worked and aged condition, 48

800 600 400 200 Tensile Results 1 ~ l100~II -1200F IOO — OF 1100 0 80 0 Longitudinal Transverse Solid points indicate specimens which fractured at pin holes or 1000~F O 0 beneath collars. 40 ~I Il1200~F A V 20 [ J I iJ I I I I I III III I [ I I I I Ii11 I I I I I1l 0. 1 1. 0 10 100 1000 10, 000 Rupture Time, Hours Figure 9, Stress versus rupture time data obtained from smooth specimens of Waspaloy in the annealed and aged condition at 1000~ and 1200~F

V) U) u) U) u) _k I I I I I I I I I II I I I I I I I I, ii I I I 'I I I I I,' I I I I ' 600 400 200 0 Tensile Results _________ 1000~F 100 80 - _ VA O - 6 —~ 0 [~~~~ Longitudinal Transverse _ v 40 | 1000~F 0 0 1200~F A V 20 I i i I [1 1 I [I I 11 1 I I I I iI [ [ I [ I I I I 11 1 I I I lJ Ii I i I I n 0 0. I 1. 0 10 100 1000 10. 000 Rupture Time, Hours Figure 10. Stress versus rupture time data obtained from notched specimens of Waspaloy in the annealed and aged condition at 1000~ and 1200~F,

8C 6C 4C 2( co u -1 m I ( _ I! I II I I...." I i II I I '11111! ~ l I! I ' '1! l I I I I 111 0 - 30 - - 0 - 10 - 1000-'F ___________ 0.__.- ----------- 0-o-1- - 0 o-.- ---— i-i IZOO'F 80 - 60 - O Longitudinal specimens ~~~~~~~~~~~~40 p { | ~~~0~~~~ Transverse specimens o10 I I I I I 1I II I I I I- I I I I I i 11 (n r 4 2 0, 00001 0. 0001 0.001 0.01 Minimum Creep Rate, Percent per Hour Figure 1. Stress versus minimum creep rate data for Waspaloy in the annealed and aged condition at 1000~ and 1200~F, 0. 10 1.0

800 600 400 200 Un; N. U) 100 80 60 1 --- —----- I 11111 ----- 1 ---\ —I I I I 1111 I N ----- I1 11111 --- — \ --- I —l I I 'l I i! ensile Results 0~[3~~~ ~ ~ 0. =..=....O1000OF 1200~F V ' Longitudinal Transverse Solid points indicate specimens 1000~F O 0 which fractured at pin holes or beneath collars 1200F A V _ I I 1 1 1 1 1 1 __ I i. I I I I I I._.....I.. I. I i I I I t I 1 1 1 1!!- i.......1- 1 1 40 20 10 0. 1 1.0 10 100 Rupture Time, Hours 1000 10,000 Figure 12. Stress versus rupture time data obtained -from smooth specimens of Waspaloy in the cold worked and aged condition at 1000' and 1200'F.

_ 800 600 400 I I I I I I I I I._ Tensile Results t,&I -rI Longitudinal TransverseI I I I Longitudinal Transverse I I I I I I I I I I I I- I I I I i I I I I I i I i I I ~ ~ I I 1000'F 0 1200~F A 0 V I I I I I I I L 200 Luu d 80 u; E 60 40 t4 40 V V, Un 00 1000~F - Transverse 1200~F - Transverse _ I I I I I I I I I I 0oz ~0' O _ 1000~F - Longitudinal,^___ ^^ 0 -\1200zF - 0- A- Longitudinal I I I I I I I I 20 - I I I I I I I I I I I I ~ vQ...................... I I I I I I I I 0. I 1, 0 10 100 1000 10,000 Rupture Time, Hours Figure 13, Stress versus rupture time results obtained from notched specimens of Waspaloy in the cold worked and aged condition at 1000~ and 1200~F.

U) (n U-1 Q) 14 cP U (n 80 '1 I I 1111 I I ' I 11 I I I 1!! I I I "I I I I I I 1 80 600 400 800~F 200 - o o~ -— ^ o o P-10- - — 0 —_ — 0'".00_- 10OOO"F I []_C_ — """ ---" - l200~F _~ 0 100 -o o- 0_ 80o60 - 0 Longitudinal specimens | 40 T0 Transverse specimens 20 10 0.00001 0. 0001 0.001 0. 01 Minimum Creep Rate. Percent per Hour Figure 14. Stress versus minimum creep rate data for Waspaloy in the cold worked and aged condition at 800~, 1000~ and 1200~F. 0. 10 1. 0

260 250 2 5 0ZO~~~ ~ ~ R oom unexpos ed 0~~~~~~~0 1 0 F Figure 15. IfuTemperdtu 220 C4 -/ 210 0 / 2 00 unexposed 0 1 2 3 Plastic Strain, Percent Figure 15. Influence of plastic strain introduced prior to stressed exposure on the ultimate tensile strength of Waspaloy in the cold worked and aged condition. 4 55

UNIVERSITY OF MICHIGAN 3 9015 02844 0421