ENGINEERING RESEARCH INSTITUTE UNIVERSITY OF MICHIGAN ANN ARBOR. MICH. NINTH PROGRESS REPORT TO MATERIALS LABORATOR Y WRIGHT AIR DEVELOPMENT CENTER ON NOTCH SENSITIVITY OF HEAT-RESISTANT ALLOYS A.T ELEVATED TEMPERATURES H. R. VociT.^hees J R.. W. Fte eman Project 2024 Air Force Contract No. AF 18(600)-62 Task No. 73605 March 31, 1955

SUMMARY Work under Contract AF 18(600)-62 has been extended to check generality of past findings relating notched-bar rupture behavior at elevated temperature to creep-relaxation properties. Past studies on cylindrical specimens of three heat-resistant alloys are to be expanded to include two new materials ( a Cr-Mo-V low alloy steel and an age-hardening aluminum alloy) and to study notch effects in flat specimens. Prior studies indicated that notch preparation methods have a major effect on rupture life of notched specimens, presumably as a result of variable residual machining stresses. An experimental ultrasonic method will be investigated in search of a method of preparing notch specimens with minimum residual machining stresses. Studies are in progress with material from three different heats of Waspaloy seeking other factors than creep and relaxation which affect notch sensitivity. Specimen geometry for both round and flat notched bars for future tests has been standardized to give the same two values of theoretical stress concentration factor for each shape. (Kt about 3. 1 and 1. 85). Experimentation in the coming quarter is to emphasize obtaining extensive data at 1100~F for the low-alloy steel, so that notched-bar rupture life may be analyzed in terms of creep properties for this material of different type from alloys considered previously. Correlations are to be sought for notches in flat, as well as cylindrical, specimens of this alloy.

INTRODUCTION This report covers tests completed in the first quarter of 1955 under Contract AF18(600)-62 in a study of factors affecting notch sensitivity of alloys at elevated temperatures. Past experimental work was restricted to smooth and notched cylin~ drical specimens of three heat-resistant alloys. For the materials and conditions studied notch weakening in rupture tests was found to be associated with high resistance to creep, with consequent slow relaxation of concentrated stresses near the notch root. Notch strengthening occurred under conditions of relatively rapid stress relaxation by a creep mechanism, A mathematical analysis was developed which successfully explained results for two particular examples with quite different notch behavior. The range of validity of the proposed analysis will be examined for other conditions already studied and by new tests covering other types of metals. Experiments with a flat specimen notched at its edges are also planned to supplement past tests using cylindrical notched bars, The summary report covering tests for calender year 1954 (See Ref. 1) mentioned two phases of the past work calling for clarification: (1) Effects of notch preparation methods on experimental notchedbar rupture life. (2) Influence of other factors on notch behavior besides creep and relaxation properties. Though neither of the studies on these topics is complete, progress up to March 31, 1955 will be covered below:

3 CURRENT STATUS OF THE EXPERIMENTAL PROGRAM Effects of Notch-Preparation Methods on Test Results Three specimens of Inconel X-550 with a notch prepared by grinding showed no evidence of surface alteration or preferential grain orientation when heat treated in vacuum after notching. These specimens should be quite free from residual stresses and if notches prepared by another means give the same rupture results as do these, the results are probably quite close to the true values for stress-free notches. Of the available methods for notching specimens with minimum residual machining stresses, an experimental ultrasonic method under development by the Sheffield Corporation of Dayton, Ohio is being considered first. Specimen blanks have been forwarded to their laboratory but actual finishing of these trial specimens has not yet begun. Other techniques will be investigated should ultrasonic methods prove unsatisfactory. Meanwhile, notches for routine testing are being finished by grinding, followed by form lapping to final size. Effect on Notch Behavior of Other Factors than Creep and Relaxation Material from one vacuum-melted and two air-melted heats of Waspaloy was obtained and rolled to a common bar size. Specimens from all three heats were given either of two heat treatments, and short-time tensile and creeprupture properties determined, Notched -bar rupture tests for the same materials and treatments are in progress. It is planned to compare notched-bar aritd smoothbar results in search for possible correlations involving properties other than creep or relaxation. New Test Materials and Specimen Types Two additional alloys were chosen for study after conferences between

4 the University of Michigan and the Materials Laboratory, WADC: (1) An air-hardening Cr-Mo-V low-alloy steel (Timken "17*22-A"S). (2) An age-hardening aluminum alloy (2024-T4). The alloy steel stock has been received and initial tests scheduled. Delivery of the aluminum alloy is expected in the coming quarter. Specimen dimensions have been established to give theoretical stress concentration factors in flat specimens machined from round stock equal to the factors for cylindrical bars used in this program. To date the only data obtained with flat notched specimens are for a few odd-sized specimens finished in the course of machine-shop trials of grinding and lapping techniques. EXPERIMENTAL RESULTS Rupture Life of Inconel X-550 Specimens Heat-Treated in Vacuum After Notching Three notched specimens of Inconel X-550 were finished by grinding in the as-received condition to a nominal gauge diameter of 0. 600-inch, 0.424inch diameter at the notch, and 0. 005-inch notch root radius. The specimens then received a conventional heat treatment after being sealed in individual Vycor glass tubes under high vacuum. The Vycor tubing collapsed around the specimen and showed pronounced devitrification during the four-hour solution treatment at 21500F, but the vacuum was retained throughout the treatment. Rupture data obtained at 1350~F follow: Spec., No. Stress (psi) Rupture Life (Hr.) NX-569 60, 000 3.4 NX-571 50,000 7.6 (i 0.2) NX-570 40,000 55.9 These rupture times fall near, but slightly lower than, the values previously found for similar specimens treated in a raw helium atmosphere after

5 turning the notch on a lathe. In the present specimens no evidence was seen of the surface alteration and preferential orientation of grain boundaries perpendio cular to machined surfaces noted in the earlier specimens. Comparison of Properties for Three Heats of Waspaloy Limited amounts of material was found to be available from one heat of Waspaloy melted under vacuum and from two different heats melted in air. Chemical analyses are listed in Table 1. It was anticipated from results reported by Carlson, et al. (pages 9 and 11 of reference 2) that notched.bar properties for the several heats might differ one from another, especially when the intermediate aging step (15500F, 4 hr, Air Cool) was omitted from some specimens. These differences were to be examined in terms of any corresponding differences to be found in the smoothbar properties. To minimize effects of different prior treatments, and to stretch the short supply of stock, all three materials were rolled to one-half inch squares at the University. Initial break-down to one-inch squares was at 2150~F. All further rolling was at 1950~F. Reduction to 5/8-inch squares was in 10 steps, with reheat after each step. The final 14 percent reduction (5/8-inch to 1/2-inch squares) was from 1950~F in four steps without reheat. Test results are presented in Figures 1 through 6. Five pages were used to cover the different creep plots of Figure 1 to permit more convenient comparisons between curves and easy determination of creep rates. The most evident finding is a considerable higher creep strength for the vacuum-melted heat tested compared with the air-melted materials.

6 TABLE 1. CHEMICAL COMPOSITIONS OF THREE HEATS OF WASPALOY TESTED Melting Atmosphere: Vacuum Air Air Heat Number: 3-260 44, 036 63, 613 Element Chemical Composition, Percent by Weight C 0. 08 0. 08 0. 04 Mn 0.27 0.80 0. 73 Si 0.60 0.61 o0.66 P 0,01 0.014 S 0. 005 0. 017 0. 014 Cr 19, 7 18.72 20.16 Ni Bal. Bal. Bal. Co 14.0 13.44 14.25 Mo 3.90 2.93 3.15 Fe 0.74 1.17 1.33 Al 1.11 1.29 1.00 Ti 3.10 2, 29 2.54 Cu 0.1 0, 1 0, 06 Mg 0.1 Figures 2 and 3 show a similar high yield strength and rupture strength for heat 3-260, compared with results for the remaining two heats. The short-time tensile and rupture data for these tests are listed in Tables 2 and 3. Notch weakening occurred in all cases for a notch with 0, 004-inch root radius in a bar with shank and notch diameters of 0. 50 and 0. 350-inch, respectively. These specimens were heat treated in an atmosphere of raw helium after turning on a lathe. For all three heats, effects on rupture life of omitting the 1550'F aging step were small and the relative position of rupture curves for notched and unnotched specimens was about the same for the three heats.

TABLE 2 SHORT-TIME TENSILE PROPERTIES AT 13500F FOR THREE HEATS OF WASPALOY Heat 3-260 Heat 44,036 Heat 63,613 aConv. H. T. bNo 1550~ Age Conv. H. T. No 1550~ Age Conv. H. T. No 1550~ Age 0.2% Y. S. (psi) 112,500 118,000 91,400 91,000 95,000 90,200 Tensile Strength (psi) 135,000 135,000 115,000 102,000 117,000 106,200 Proportional Limit (psi) 92,000 85,000 67,500 77,000 75,000 73,000 Elongation (%/1.4 in.) 16. 16. 4. 5 3.5 7.5 4.5 Reduction of Area (%) 17.5 16. 7.5 11.5 9. 9. (a) 19750F, 4 Hr., Air Cool + 1550~F, 4 Hr., Air Cool + 1400~F, 16 Hr., Air Cool (b) 1975 F, 4 Hr., Air Cool + 1400~F, 16 Hr., Air Cool

TABLE 3. RUPTURE DATA AT 13500F FOR THREE HEATS OF WASPALOY SMOOTH SPE CIME NS Heat 3-260 Heat 44,036 Heat 63,613 Stress Rupt, Life Redo o. Efng' Rupt, Life'Red0 of Elonlong. Rpt Life Red. Oof Elong (psi) (Hr.) Area( (o) ( (Hr.) Area(%o) (%o) (Hr.) Area(7o) g/o)_ A. Conventional Heat Treatment (1975~F, 4 Hr., AC + 1550~F, 4 Hr, AC + 14030~F 16 Hr., AC), 100,000 2, 32 11. 7, 5 -. _ 901,000 5. 25 6. 5 4. - - - _ 80,000 21,7 9. 5.5 1.23 8.5 3. 2.48 6. 5 3.5 70,000 36.6 7.5 3. 5.35 7. 2.5 7.0 7. 3. 60,000 155.4 6.5 4. 42.9 5.5 3.5 11.4 6.5 2. 5 50,000 - - - 108.5 3. 3. 5 189, 9 4, 5 1. 5 40, 000 - - - 820.95 5. 4. 550. 8 4. 4. B. 15500F Aging Step Omitted (1975~F, 4 Hr., AC + 1400~F, 16 Hr., AC). 100,000 1.28 8. 2. -... 90, 000 2, 75 8. 5 3, -. 80, 000 16 1 5, 5 3.5 0. 55 - - 3. 15 11. 2. 5 70, 000 46.4 6. 5, 5 4.0 10.5 2.5 7.0 8. 3. (to, 2) 60,000 49, 1 6.5 3.5 25,05 8.5 2. 11.3 6.5 3. 50,000 - - - 41. 9 1. 5 1.5 142. 5 4. 3, 40, 000 - - 865. 6 5. 4 5 634. 5 7. 4 5 00

TABLE 3. (continued) aNOTCHED SPECIMENS Stress Heat 3-260 Heat 44,036 Heat 63,615 (psi) Cony. H. T. No. 1550~Age Conv. H. T. No 1550~ Age Conv. H. T. No. 1550~ Age ( Rupture Lives - Hours) 70,000 1.0 -.-.- _.. 60,000 -- 2.6 -- -- -- 55,000 11.3 -- -- 50,000 -- 2. 2 0.45 -- 0.6 1.5 45,000 9.0 --.... 40,000 b1038+ 1.2 1.3 1.25 29.6 35,000 --....2.6 14770 8 32,500 -- b853+ -- b894+ - 30,000 -- _ - b1320+. __ (a) Notch geometry: Shank diameter, D = 0. 500 inch Diameter at notch, d = 0. 350 inch Notch root radius, r = 0 0.04 inch Notch Angle, 600 Heat treated in raw helium atmosphere after notch machined on lathe. (b) In progress. so

10 Preliminary Studies With Flat Specimens The extension of the contract for this investigation calls for tests on flat specimens notched on the edges to develop biaxial stressing. Studies are planned to include the same two values of theoretical stress concentration to be used in further tests on cylindrical test bars. As is explained in Reference 1, calculation of actual stress levels in notched specimens is uncertain for notches with extremely-small root radii. For this reason, future notch tests on round specimens are to use a root radius of either 0. 020 or 0. 080 inch. The corresponding theoretical stress concentration factors (Kt) are, respectively, about 3. 1 and 1. 85 when the shank diameter is 0, 600 inch and the notch cross section half that of the shank. Design of suitable flat specimens with these theoretical stress concentration factors involves compromise among several often-conflicting factors: (1) In the interest of uniformity of material, it is highly desirable that all types of specimens come from the same heats of metal and that all specimen blanks have a common history prior to machining or heat treatment. In particular, it is possible that differences in fabrication of sheet and round stock would cause variable response to later treatments, Machining of flat specimens from round stock would eliminate many difficulties often encountered with gripping and alignment of strip specimens. (2) For biaxial stressing, specimen thickness should be small in comparison to its width: a width/thickness ratio of 4/1 is considered to be about the minimum acceptable value, with 8/1 preferred. For the 3/4-inch diameter round stock on hand for this program, the resulting flat specimen must be quite thin. However, a thickness less than about 0. 100-inch appears impractical to machine. (3) Tooling would be simplified if the same two root radii were used for both round and flat specimens.

11 (4) It might be desirable from the standpoint of later interpretations if the notched cross section cover the same fraction of the shank area in both round and flat notched bars. Starting with 3/4-inch diameter round stock, a flat 0. 100-inch thick and 0. 740oinch wide can be obtained. The most critical remaining dimension is the width at the notch. A change to a shallow notch would permit somewhat greater width/thickness ratio, but the resultant localization of the stress concentration makes the shallow notch more prone to variability from minor deviations in specimen geometry and makes analysis of stress changes more critical. Using the borderline width/thicknes's ratio of 4/1, a 0.031inch root radius is required for Kt = 3. 1, and 0. 098-inch for Kt = 1. 85. The convenience of only two root radii will be sacrificed for the other considerations involved, and the above dimensions adopted as "standard" for the present series of tests. Before the specifications for flat notched specimens had been settled, a few specimens with varying geometry were prepared while machining techniques for flat bars were being perfected. Test results obtained to date with these specimens are listed in Table 4.

TABLE 4 RUPTURE PROPERTIES AT 1350 F FROM PRELIMINARY TESTS ON FLAT SPECIMENS Stress Rupture Life aNominal Specimen Geometry (inches) How Notch was Spec. No. Alloy (psi) (hours) W w t r Finished SMOOTH SPECIME NS FS-S(B)27 S-816 40,000 83.5 0.400 - 0- 0o100 FS-X562 Inconel X550 65,000 19.2 0.400 -- 0.100 -- - NOT CHED SPECIMENS FN-S92 S-816 45,000 40.7 0. 730 0.470 0. 125 0.005 7.2 Shaped FN-S91 S-816 40,000 119.3 0. 730 0.470 0.125 0. 005 7.2 Shaped FN-S93 S-816 42,000 110.6 0.730 0.470 0.125 0.060 2.45 Shaped FN-S94 S-816 50,000 37.9 0.620 0.310 0.100 0.025 3.1 Ground, lapped FN-X560 Inconel. X550 61,400 9.2 0. 620 0. 310 0.100 0. 025 3.1 Ground, lapped FN-X561 Inconel X550 50,000 32.5 0. 620 0.310 0.100 0.025 3.1 Ground, lapped (a) W = Width of unnotched gauge length w = Minimum width (at notch) t = Thickness of bar r = Notch root radius Kt = Theoretical stress concentration factor ( in axial direction). * N

13 DISCUSSION OF TEST RESULTS Properties of Three Heats of Waspaloy The several plots of Figure 1 show little effect on creep properties when the intermediate (15500F) aging step is omitted from the conventional heat treatment. Where differences are found, the conventional heat treatment results in the higher creep for any given stress level. For the same stress levels, and with conventional heat treatment, heat 44, 036 showed more creep than heat 63,613 at 80,000 and 70,000 psi (Fig. 1(B) and 1(C)), but the reverse was noted at 60,000 and 40, 000 psi (Fig. 1(E) and 1(D)). Possible tendency for a more prominent primary creep stage was noted for heat 63,4-613 compared with heat 44,036. Comparative creep properties for the three Waspaloy heats are more easily visualized from Figures 4 through 6, where the creep rates are shown as a function of stress level. Besides the minimum creep rate, initial creep rate and creep rates at different percentages of the rupture life are shown by separate curves on these figures. The 15500F aging step had no apparent effect on the creep rate for heat 3.260 at any portion of the tests, from initial loading until rupture (Fig. 4A). For the other two heats9 omitting the intermediate age had no effect early in the test, but near the end of life a slower creep rate resulted at high stress levels (Fig. 4, B and C). Even in this case, variation in creep rates for the two heat treatments is probably too small to have recognizable effects on results calculated by the analysis proposed in Reference 1. Comparison of Figures 5 and 6 shows that the minimum creep rate for heat 3-260 occurred rather early (from 5 to 15 percent of the life) and that the creep rate after about 50 percent of the life exceeded the initial rate. For both air-melted heats,the minimum rate occurred somewhat later (12 to 25 peru

14 cent of life expired) and the creep rate remained below the initial rate until very near rupture. The consistently-higher tensile and rupture strengths exhibited by the vacuum-melted material may be due to higher titanium content but may be at least partly the result of different prior history. Heat 3-260 was rolled to final size directly from a 10-pound ingot, whereas, the other materials were from large commercial heats and had been submitted to a rolling and annealing schedule before final rolling at the University of Michigan. The magnitude of effect to be expected from this difference in prior history is hard to estimate, but one producer of Waspaloy has stated in a private communication that he has observed occasional changes in notch behavior when material from a given heat was rerolled to another size of bar stock. It should be noted that the notch used in the tests to date on these three heats of Waspaloy gave a high stress concentration factor (7. 2), so that localized plastic deformation should be expected near the notch root in all cases. Future tests will use a notch with more moderate stress concentration factor. The fact remains that the lack of marked change in notch rupture strength with omission of the 1550'F aging step agrees perfectly with the corresponding lack of differences in any other property measured for the two heat treatments involved. A short length of the 1-3/4 inch diameter bar stock of heat 63, 613, supplied by the manufacturer, is still on hand. It is possible that specimen blanks cut from this "as received" material may exhibit an effect of the intermediate aging step on its notched-bar behavior. If such an effect is found, smooth bars in this same condition can be examined for corresponding differences in other test properties.

15 Preliminary Results for Flat Specimens The 83, 5-hour rupture life at 40,000 psi for the flat strip specimen of So816 compares with about 80 hours for round specimens (See Fig. 1, Ref. 1), while Fig. 6 of the same reference gives a life of about 13 hours for InconeliXo550 at 65,000 psi, compared with the 19.2 hours found for the flat strip of this alloy. Deviations in rupture life between round and flat unnotched specimens for the two tests are within normal scatter. Unless conflicting findings arise in two remaining tests in progress, it appears that the Curves already established from round specimens can be applied directly to unnotched flats. This result should be expected for conditions where surfaces deterioration during testing is slight, as is the case at 1350~F for the superalloys under study. Data on flat notched specimens are too sparse for general conclusions. The S.816 was still strengthened, but to a smaller extent than for round specimens. Three flat bars notched on the shaper showed only a few thousand psi higher strength than for smooth specimens, which result may reflect the probable high degree of cold working in this method of finishing. Results for the two completed tests on flat notches of Inconel X-550 fell near those reported by Carlson, et al (Ref. 2) in their Figure 5 for round bars with ground notches having a like stress concentration factor (0, 020-inch root radius).

16 FUTURE. WORK During the coming quarter, experimental work is to continue with the limited remaining stocks of the original three alloys in efforts to clear up effects of machining methods, rupture strength of flat versus round notched specimens, and differences between the three Waspaloy heats with and without an intermediate aging step in the heat treatment. Major emphasis, however, will be devoted to getting extensive test results for the "17.22-A"(S) alloy at 11000F so that the analysis developed for the original three alloys may be checked for validity with this different type of material. Once rupture curves for flat notched specimens have been firmly established for any of the metals under study, experimental results will be used to test the applicability of the analysis proposed in earlier work for round notched bars.

17 BIBLIOGR APHY 1. Voorhees, H. R. and Freeman, J. W, Notch Sensitivity of Heat.Resistant Alloys at Elevated Temperatures. Part 2 Analysis of Notched-Bar Rupture Life in Terms of Smooth-Bar Properties. Preliminary Copy, WADC TR 54-175, Part,, December 1954o (In process)o 2. Carlson, R. L,, MacDonald, R. J., and Simmons, W. F. Investigation on Notch Sensitivity of Heat-Resistant Alloys at Elevated Temperature,(Rupt.ure Strength of Notched Bars at High Temperatures)~ WADC TR 54-391, October 19540

0.020 _____________________________ To 155.4 Hrs. Code Heat No. Heat Treatment o 44036 1975~F, 4 Hrs.,A.C.+ 1550~F,4 Hrs.,A.C.+ 1400~F, 16Hrs.,A.C. o 63613 1975~F, 4 Hrs.,AC. + 1550~F, 4 Hrs.,AC.+ 1400~F, 16Hrs.,AC. 0.016 L ~ 636 13 1975~F, 4 Hrs.,AC + 1400~F, 16Hrs.,A.C. To 108.5 Hrs. A 3-260 1975~F, 4 Hrs.,AC.+ 1550~F,4 Hrs.C.+ 1400~F, 16Hrs.,A.C. l/~~~~~~~ /Xt~ < T t I 1 I I I I ITo 189.9 Hr. 0.014 0.012 0.010- - -~- _ ~- - - - _ - - - - - To 142.5 Hr /3 0.006 - - ~ - 0.002 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 Time (Hrs.) FIG. I (A)- CREEP CURVES AT 13500F FOR SPECIMENS FROM THREE HEATS OF WASPALOY WITH TWO DIFFERENT HEAT TREATMENTS.

0.020' To 2.32 Hrs. To 2.48 Hr-. 001I Code Heat No. Heat Treatment o 44036 A * 44036 B o 63613 A 0.016 0 63613 B /a 3-260 A O T OA 0.6 rs la~~~~~__ 08 L I. l23-2 60 8 0.04-To 1.32f Hrs. /Heat Treatment I/ ~~~~~~~A -- 1975F, 4 Hrs.AC+15500F,4 HrsAX 1400 F, 16 Hrs., A.C. G. jB )CB - 1975!F 4Hrs., A.C. 1400F, 16 Hrs.,A.C. 0.012o 0.010'/ 0.0,"/.-/0 9:I I / I I I I I i To II,5 Hrs. 0.008 0.006 ~~~0.004 1 I _p IJ To 4.0 Hrs.'o?.0 Hrs. 70 psi I 00., 0 02 OA 0.6 0.8 1 12 1.4 1.6 L8 2 22 2.4 2.6 2.8 3 Time(Hrs.) FIG. I(B) — CREEP CURVES AT 1350~F FOR SPECIMENS FROM THREE HEATS OF WASPALOY WITH TWO DIFFERENT HEAT TREATMENTS.

0.060 To 232 Hr j 0.056 Code Heat No. Heat Treatment o 44036 1975~F, 4 Hrs.,A.C. +1550F, 4Hrs.,A.C.+ 1400F, 16Hrs.,AC~. 0.052 - _04 * 44036 1975~F,4Hrs.,AC. * 1400~F,16Hrs.,A.C. o 63613 1975F,4Hrs.,AL +1550~F,4 Hrs.,A.C.+ 1400F,16Hrs.,A.C. a 3-260 1975~F,4Hrs.,AC. +15500F,4Hrs.,A.C.+1400~F,16Hrs.,A.C. 0.048 t 0.044 ^ i 5.25 Hrs. Z 0.032, 1 3 4 5 6 7 0.020'' /, ~~~~~~~TTIME (HRs.)5.35 0.04o l0!, oo 0 2 3 4 5 6 7 HEATS OF WASPALOY W'ITH TWO DIFFERENTHEAT TREATMEN.TS.

To 550.8 Hrs. 0.030 Code Heat No. Heat Treatment To 6345 Hrs. 0 44 036 1975~F 4 HrsA.C.+ 1550F, 4 Hrs.AC. 1400~F) 16 Hrs.,AM. ~ To 82 0.9I Hrs. 0.028 ~ 44036 197F, 4 Hr s.A.C.+ 1400fF 16 Hrs._A.C. o 63 6 13 1975~F 4Hrs.,A.C.+!550~F,4 HrsA.C.+ 1400 F 16 Hrs.,A.C. * 63613 197 5F, 4 Hrs. A.C.t 1400~F, 16 Hrs., A.C. 0.026- 0.024 0.022 ~~~ 0.020 ~~~-t IIIIIIrIiIIIII I! To 86,5.5 Hrs. Z 0.018 Un 0.01u 0.014~_~ 0.008 — ~~0.002 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 TIME (HRS.) FIG. I (D)- CREEP CURVES AT 135&F FOR SPECIMENS FROM THREE HEATS OF WASPALOY WITH TWO DIFFERENT HEAT TREATMENTS.

0.030 To 2L7 Hrs. 0.028 Code Heat No. Heat Treatment o 44036 A,i ~ 44036 B 0.026 a 63613 A a 63613 B A 3-260 A 0.024 A 1 I I 1I ~ 3-260 B ruptured Heat Treatment 0.022 A 1975F, 4 Hrs.,A.C.+ 1550F, 4 Hrs.,A.C.+ 1400~F, 16 Hrs.,A.C. B 197eF, 4 Hrs.,A.C. 1400F ) 16 Hrs., A.C. 0.oeo 0.T010 o 0To 42.9 Hr.4Hr. 0.008 ____T. H~ Bci 0.006 a.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 0.004 w~~~~ U~ ~~ 0.002 0.010 To 42.9 Hrs..9Hrs 2050,0To 7__OOOpsi -60Ops To 49.1 Hrs. 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 TIME (HRS.) FIG. I(E) - CREEP CURVES AT 13500 F FOR SPECIMENS FROM THREE HEATS OF WASPALOY WITH TWO DIFFERENT HEAT TREATMENTS.

130,000 120,000 l 110o,ooo000 100,000 90,000 ~ 70,000 0"',000 Code Heat No. Heat Treatment o 44036 A 50,000 * 44036 B o 63613 A * 63613 B 40,000 / 3-260 A A 3-260 B A - 19750F, 4 Hrs.,A.C.+ 15500F, 4 Hrs.,A.C.+ 14000F,16 Hrs.,A.C. 30)000 B - 19750F, 4 Hrs., A.C. + 14000F 16 Hrs.,A.C. 20,000 0, lo,ooo 1 0 0.002 0.004 0.006 0.008 0.010 0.012 0.0 14 0.016 0.018 0.020 Strain (in/mn) FIG. 2-INITIAL PORTION OF STRESS-STRAIN CURVES AT 1350~F FOR THREE HEATS OF WASPALOY WITH TWO DIFFERENT HEAT TREATMENTS.

100 000 " 60OOC S.o.__ Ba___ n 40 00C — 15 EOI E h10f e d 1T _itche d B ar IN RESS 20,000 0.1 2 3 4 6 7891 3 4 5 6 7 8 7 1 2 3 4 5 6 7 8 100 2 3 4 5 6 7 1 000 2 3 4 5 6 o10,oo000 RUPTURE LIFE - HOURS FIG.3_ - STRESS VERSUS RUPTURE LIFE AT 1350~F FOR CYLINDRICALHe at -No.-63 613 Ntch20 G r D I nch -Bars- Ps- -U L- HO UR I 40,000 " cnr___ _ - - -40,000-0 %CONVENTIONAL HT....... —. - _B -- I.-Cn~~ SMOO__ ___ Nthed-R —arI IN PROGRESS 0.1 2 3 4 5 6 7 9 3 4 5 6 7 8 10 2 3 4 5 6 7 86100 2 3 4 5 6 71,000 2 3 4 5, 10,000 RUPTURE LIFE - HOURS c- 40,000 RCONVNTIONAL H.T. SMOOT BARS 0,00p 1550 F- AGE OMITTE.....- — _ I- * CONVENTIONAL H.T. 567610 C P 1550~F AGE OMITTED I(NOTCHEDB' BARS 001 781 2 4 5I 2 3 45678100 2 3 4 5 671,000 2 3 4 56 10,000 RUPTURE LIFE - HOURS AND SPECIMENS WITH A CIRCUMFERENTIAL NOTCH FOR THREE HEATS OF WAS PALOY. Notch Geometry: D=0.500 d=0.350 r=0.004 inch

120,000 o, 0 Conventional Heat Treatment ~ a A 1550'F Intermediate Aging Omitted 90I000 00 0.000 001 l0.00001 0.0 001 0.00 1 11 0.01 0.l? 0,000 o o I I I I I I I I 0oo /-. 70,000 Creep Rate (In;/In,/Hr.) FIG. 4(A) - EFFECT OF INTERMEDIATE (I550~F) AGING TREATMENT ON CREEP RATE AT 0,000 OF WASPALOY (HEAT NO.3-260) 50,000' ~'U"0 30,000 2 3 4 3 5,7 2 3 4? 2 7 ~ 2 3 4 J ~ s a s 2 3 4 3.,..9 3 Creep Rate (In.~n/Hr.) FIG. 4(A) - EFFECT OF INTERMEDIATE (1550~F) AGING TREATMENT ON CREEP RATE AT 135d'F OF WASPALOY (HEAT NO. 3-260)

100,000 eooo o a a Conventional Heat Treatment * U A Single Age Only 80,000 70.00 1 40P000 o /-' ~ I.~o/ /~/l 60,000 30,000 40,000 00.000 001 3 5 0.000 01 2 4 0.0001 a 4 * 0.001 2a 4 0.01' 0.1 Creep Rate (In.//ln r) FIG. 4() — EFFECT OF INTERMEDIATE (1550'F) AGING TREATMENT ON CREEP RATE AT 1350 F OF WASPALOY (HEAT NO. 44036)

100)000 80,000 70,I000 I I I I I 1-1 I I - I 1 I I I I I I I l o Conv n tin Hea - 70,000 AO,~- - - 60,000 /-/ oe Initial Creep Rate,~ 50,000 - - I 1 l[1lrl TO[ om Minimum Creep Rate FIG 4C E OF Intermediate Aging Omitted 3, 0,000 (E 40000 103000 0 0.000 001 2 4 6 0.000 01 2 4 6 0.0001 2 4 6 0.001 2 4 6 0.01 2 4 6 0.1 Creep Rate in./An./Hr.) FIG. 4(C)- EFFECT OF INTERMEDIATE (15500F) AGING TREATMENT ON CREEP RATE AT 1350~F OF WASPALOY (HEAT NO. 63613)

120,000 o Initial Creep Rate * 5-15% Life Expired (Minimum Creep Rate) o110o,000 0ot 30% Life Expired * 50% Life Expired a 70% Life Expired 100,000 ~ 90% Life Expired A 95% Life Expired 90,000 -- 80,000 001 0.00001-0.000 1 0.001 0.010.1 5 70,000 Creep Rate (In/ln./Hr.) FIG. 5-STRESS VERSUS CREEP RATE AT 13500F FOR VAClUUM-MELTED WASPALOY HEAT NO. 3-260 WITH CONVENTIONAL HEAT TREATMENT

100,000 Initial Minimum Creep Rate 80% z' Creep 10-25% of Life Life \ 80,000 Rate Expired Expired Heat No. X 7o X 636131 2* 3~ 4A5 7 9 2 4 4036 —-- 70,000 11 60,000 50,000 40,000 30,000 40 000 0 02 3 4 5 6789 2 3 4 5 6 789 2 3 4 56 789 2 3 4 5 6789 2 3 4 5 6789 0.000 00.1 0.000 01 0.000 I 0.001 0.01 0.1 Creep Rate (In./An./Hr.) FIG.6- STRESS VERSUS CREEP RATE AT 1350~F FOR TWO AIR MELTED HEATS OF WASPALOY WITH CONVENTIONAL HEAT TREATMENT