ENGINEERING RESEARCH INSTITUTE UNIVERSITY OF MICHIGAN ANN ARBOR BIMONTHLY PROGRESS REPORT NO. X THERMAL-SHOCK INVESTIGATION By A. R. BOBROWSKY L. L. THOMAS Project M949 WRIGHT AIR DEVEDPMENT CENTER, CONTRACT AF 33(058)-21254; E. O. U. S. AIR FORCE NO. 605-227 SR 3a Marqh, 1953

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ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN BIMONTHLY PROGRESS REPORT NO. X THERMAL-SHOCK INVESTIGATION OBJECT The object of this research is to evaluate optimum design of test specimens and criteria which will permit correlation of thermal-shock data with performance of the material in the form of turbine buckets. SUMMARY Thermal-shock tests were run on wrought S-816 alloy that had been solution-treated and aged. Nominal test temperatures were 1600, 1700, and 1800B0F. The resistance to cracking of these heat-treated specimens was the same as that of specimens tested in the as-received condition. Thermal-shock resistance of S-816 alloy decreased monotonically and smoothly with increasing temperature. On a comparative basis, S-816 alloy is inferior in resistance to cracking by, thermal shock to the best N-155 alloy at all temperatures and to practically all Inconel specimens at 1700'F. The scatter of results was smaller than in most previous tests. INTRODUCTION Previous tests on wrought S-816 alloy in the thermal-shock rig had been conducted on the alloy in the as-received condition. Inasmuch i'

I ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN as commercial uses of the alloy frequently dictate a heat-treatment, it was felt that tests should be run on specimens that had been solution-treated and aged. Moreover, it was believed that the test temperature of 1500~F previously employed was too low for tests of reasonable duration. Tests were conducted on heat-treated specimens at nominal temperatures of 1600, 1700, and 1800~F during the period December 11, 19535 to February 11, 19535. APPARATUS AND PROCEDURE The test rig employed in these tests was identical with that described in the latest progress reports. One test unit consisting of air nozzle, specimen holder, and radiation pyrometer was used for all tests in order to eliminate differences in results that might be introduced by variations in test units, The test specimens were machined from 3/4-inch diameter rod. After machining, the specimens were solution-treated simultaneously for 1 hour at 21500F, water-quenched, and aged for 16 hours at 18000F. Four specimens were tested at each of three maximum cycle temperatures, 1600, 1700, and 1800~F. Of the three possible edges available for use as the cooled edge on each specimen, the most nearly perfect edge was selected as the cooled edge. Specimens were viewed by a telescope, as previously reported, to detect cracks. The criterion of cracking was the presence of a crack completely across the cooled edge of a specimen...RESULTS.. The results of tests on heat-treated specimens are given in Fig. 1 together with previous results on specimens tested in the as-received condition. The specimens reported in the present report are Nos. 9 through 20; the specimens from previous tests used for comparison are Nos. 3 through 8. i 2

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Two specimens which were to have been run at 1600~F were actually run as follows~ No. 16 1615~F No. 20 1660~F The resistance of these specimens to cracking is in line with the results from other specimens if the higher test temperature is taken into consideration. The tabular results are as follows..Number of Cycles to First Crack at 16000F 1L700 1800"F 5130 2426 1069 -4600 1903o 956 -3620 (16150F) 1956- 1146 3100- (16600F) 2300- 784 The specimen run at 1700~F that shows 1903 cycles to failure._was actually found not to be cracked completely through the cooled edge; rather, a crack 0.031 inch long was present in a 0.034-inch edge. The test was stopped because it was felt that oxide had -filled the lower 0.003 inch of the crack, but microscopic observation of the cleaned edge showed..the incompleteness of the crack. Based on past experience with crack propagation, it is felt that the actual number of cycles to failure would have been closer to 2000 cycles than to 1900 cycles. The three specimens tested at 1800~F that show 1146, 1049, and 956 cycles to failure all had cracked somewhat beyond the edge thickness. Oxide obscured the cracks to some extent, so that crack detection was difficult. The actual numbers of cycles should thus be less than those shown, probably below 956 cycles. The two specimens tested at 1700~F showing 2300 and 1956 cycles to first cracking and the specimen tested at 1660~F all had passed the number of cycles to first cracking by the time the test was stopped. Oxide obscured these cracks so that actual.determination of crack length was difficultt. It is estimated that scatter of results is about 15 at 6oo0 and 1800~F, and about 20% a~t 17000~. The data are relatively consistent within. this range of scatter. 3

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Specimens previously reported were tested in the as-received condition at 1500, 1600, and 1700~F. Results from these tests fall along the line of results from the present tests. It appears that the heat-treatment used did not appreciably alter the thermal-shock resistance of the wrought S-816 alloy, but the treatment may have increased the reproducibility of results. The wrought S-816 alloy specimens were poorer in resistance to thermal cracking than the N-155 alloy, lot I, previously reported, and about the same as the N-155 alloy, lot II, previously reported. Inconel specimens were tested extensively only at 1700'F; practically all of the Inconel specimens were superior to the S-816 alloy at that temperatura., CONCLUS ION 1. The heat-treated wrought S-816 alloy specimens manifested thermal-shock resistance that decreased smoothly with increase in test temperature from 1600 to 18300~F 20 The results from wrought S-816 alloy in the heat-treated and as-received conditions are about the same at 1600 and 1700~P, the only two test temperatures available for comparison. Scatter of results from the heat-treated specimens was smaller than from the as-received specimens. 3. Heat-treated wrought S-816 alloy is inferior to N-155 alloy, lot I, but is about the same as N-155 alloy, lot II, in resistance to thermal cracking at temperatures from 1600 to 1800~F At 1700~F, Inconel in most cases outperforms S-816 alloy in resistance to thermal cracking. 4

FIG. I S-816 ALLOY' I,000O I 13,280 I 10,000. SOLUTION TREATED I HR AT 2150~ F O WATER QUENCHED AGED 16 HOURS AT 1800" F * AS RECEIVED ACTUAL NO. OF CYCLES TO CRACKING SOMEWHAT LESS THAN SHOWN ACTUAL NO. OF CYCLES TO CRACKING SOMEWHAT GREATER THAN SHOWN Jv (C C, 8,0 C P '?nr _ ' ' I i..1..__ I! 0-.) 3 6,000 0 5,000 -: I r 2,000 0 2,000 1,000 0 I I I ) 1615 F 1,.660. F....., i........... 1500 1600 1700 1800 MAXIMUM CYCLE TEMPERATURE,OF

--- ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN KEY TO LOG Column (: Column (,. PO Po I 1) (1) Relative position on bar stock 1 Specimen number 2) Arrow indicates direction and location of cooling jet; coc medium is air unless otherwise stated W Cooling medium is water 45 Width of cooled edge, inches F. Previously subjected to rotating beam fatigue as shown in column (6) X Failed during pre-fatigue aling Column (3) M Thermal shock cycle manually controlled 1500/5 Automatic cycle control' maximum temperature, ~F, and length df cooling period, seconds' P1800 Dead load, 1800 lbs +10/100 Starting with stated maximum temperature, ma;imum temperature was increased 100F after each 100 cycles 40W5K Reversed-bending (rotating-beam) fatigue tests; maximum stress, 40, 500 psi to 1800 Maximum temperature held constant after 1800~F was reached Column (4) A W no symbol Column (5) 0 F C G FC.PC Air cooling for stated number of cycles Water cooling for stated number of cycles Air cooling for stated number of cycles No failure visible Fracture Cracks Grooves Face crack Possible crack Column (6) B Specimen warped due to thermal strains A 0.14 Area of cross section, square inch T300/1600 Heat treated before testing 300 hr at 1600~F G1500 Grooves first appeared at 1500 cycles OH Stated maximum temperature was exceeded due to malfunction of control unit BT Broke through to thermocouple hole A-1

I ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN 40. f5/ 8200.. N +100/5108 Check II P PT1 TC II C20/1700 Previously subjected to 82000 cycles at 40,500 psi Reproducibility test Specimen formed a neck due to tensile strain. Maximum temperature was increased 100~F at 5108 cycles. Second test to determnint the effect of'alteration: of teSting procedure. Study of crack propagation Previously subjected to tensile strain of 1% at room temperature Long-time test at reduced severity, Test No. I Heat treated as shown in braces ( 3. Lot No. I Heat treated for 20 hours by heating to 1700~F and allowing to cool for 5 seconds by natural convection. I A-2

TIEST LOG Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5). (6) Type 304 Stainless Steel 1 u M 0 B 2 VJ 1600/10 4400 A C B 300 W 3 16oo00/4 1783 C 4a Fatigue 40. 5K 3300 F 4b Specimens 40. 5K 2600 F 5 \Q/ 170o/4 1100 0..47V 1800/4 675 C ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,,,...... 6 1600/4 1900/4 6240 1240 G6500 0 C 7. P 6001500/4 4130 F A 0.16 P600 A-3

TEST LOG (cont) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5) (6) i_,,... _ _. -.. 8 (7) 1600/5 3082 0 T300/1600 1800/4 517 C 9 A 1500/3 5753 0 1600/4 1000 0 10 1700/4 1000 0 1800/4 80 C 11 (j 51500/5 1000 F A 0.132 ~V P1800 1500/5 P600 5000 0 A 0.133 12 P900 1200 0 P1800 203 F 13 & 1600/4 128'4. C G 115 14 1500/4 1000 F OH 15 16oo00/5 1900 C T300/1600 16 60 --- 409 C 16 4 > 1600/5 409 C ~ A-4

ITEST LOG (cont) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks (1) ~(2) (3) (4) (5) (6) 17 ) 1500/5 300 F A 0.140 P1800 18 1800/4 1950 C G 1500 19: V 1700/3 5wW 1C 20 1500/3 1000 0 BT Type 347 Stainless Steel a1 w1600/4 866 C * O,3Ir +10/100 2 1600/4 1147 C.ozo0 +10/100 3 1500/4 +10/100 575 C BT 4a Fatigue 54K 520.0 F 4b Specimens 54K 10400 F 40.5K 82000 A-5

TEST LOG (cont) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5) (6) II III. i i,.... ' 5 A._s 1500/4 +10/100 1326 C 6 0 15o00/4 1990 C +10o/100 (a ~ z1600/3.5 7 +10/100 2700 G to 1800. l 1 1 1 _ Ji. i.i i. 1..-. i. l _ I. I. I. I.... 8 (Defective) g _~o35 1600/4 2863 C R.016,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 10 E.2 1600/4 3787 C Check II I,.I.-, I.,..l,..,.i i... i i.. 11 o 16oo00/4 2580 C ___. 0.. o 12 S12S, < 1600/4 3162 C G 736 13 O02 1600/4 2204 C G 2072 I ~ ~.,. ~I.. I,.., _., 14 z 1600/4 2707 C G 2604,, __... '. 1. ~0~.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A-6

TEST LOG (cant) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5) (6) 15 1600/4 3003 C G2820 R )r.O3 16 '7 1600/4 2518 C R OZ, 17 1600/4 4850 0 Check I, ~,,,,,,. _. 18 Fatigue 7200 F 54K V 64K 103300 19 ^WAC 1600/4 1825 C R 37K/217100 42K/looo000 ' 20 Fatigue 4300 F 48K/35600 64K 54K/10000 - 59K/10400 ~7 21 1600/4 - 4430 C 22 (Defective) 23 1600/5 2962 C 24 / Fatigue 0V, 10 552900 F A-7

TEST LOG (cont) Specimen Cross Number Type of Number. Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5) (6) 25 1600/5 1562 C 54K/50000 P.F. 53K/52000 59K/12000 26 1600/5 1960 C 64K/1000 70K/1000 75K/500 X 53K/52000 27/o P.F. 59K/11300 53K/52000 59K/12000 28 1600/5 1594 C 64K/1000 -,0/oo P.F. 70K/1000 75K/500 53K/52000 59K/12000 29 X C 64K/oo1000.rV o/o P.F. 70K/1000 75K/300 e1'30 1600/5 1973 C,., 31 oV o 1600/5 2764 C 32 1600/5 1500 C 32 / 1600/5 1500 C-8 A-8

TEST LOG (cont) Specimen Cross Number Type of Number' Section Cycle of Cycles Failure Remarks (1) (2) (3) (4) (5) (6) 33 X (4).o#o P.F. F 59K/32600 (3 \ / P.F. 1811 C 60K/39000 (3) 35 (2) (Used for calibration of Heat-Eye) 36 1600/5 1859 C. 58K/30000 (1) -- V.oto P.F. 37 37)..,-fo, 1600/5 4635 C -38., - 1600/5 2114 C T/200C 39 G 2440 (7) g 1600/5 2440 G Rigid Support (.._~~~~~~~~~ ~Nozzle No. 3 (8)40 y i 1600/5 3143 G Nozzle No. 4 G 2000 41 1600/5 2710 C Rigid Support Nozzle No. 3 A-9

TEST zOG (cont) (:1) (2):(3) (4) (5) (6) -Specimen Cross 'Iumber Type of Number section Cycle of Cycles ailur Remarke l42~ ~ (used for calibration) 43 P (1) i60oo0/5 10708 C Rigid Support.025Ve NOzzle twn, 4 44!07 1600/5 2046 C T2/2000.~035 +'45 1600/5 1956 C T2/2000 - 025 + H.S. 21 (vitallium) Cast 1 T 1500/3.5. iooo C BT Inconel 1 1500/3 1450. C.2. \ 1500/3'. 2730 d ~.4.Voo +10/100 ~3 W1500/3 428 C... 0..35 4 /7 L700/.5 3167. C 5 1700/5 1819. vC T2/500.035V_ -_l/V4 A-10

TEST 'LOG (cont) (-t) (2-) (3) (') (:) (6) Specimen Cross Number Type of!Number Section Cycle of Cycles Failure Rearks 6 160Q/4 7449 C.35 I~ -I ---- /Ikn ' 7.035VC 1700/5 4706 C -L/ I., T1/3/140Q 8. \ / 1700/5 2090 C PTI,025 v.. ~E.29 \1700/5 6465 C T2/800 10.1700/5 368o PT1..035V -.0 S T1/3/1400 1700/5 1884 C.0 C Vf 220/17qo..... l,...... i.....l', - 1J /7 T1/3/1400 1700/5 2500 C. PT1.025 V T1/3/1400 15 1700/5 2804 C PT10 14 1700/5 2270 C PT --- i, l.."... 16 '. 0.Z700/5' 3590 ' PT0:.. A-11

TEST LOG (cont) (1) Specimen Number Cross Section (:3) Cycle (4') Number of Cycles (.5) iype of Failure (6) Remarks 18 77 100/ 2576 PC Tl/3/1400!8 ~ 7.V * 70o5 3015 C PT5 _...._...-, '...... 19 1700/5 i8~0 C PT1O Tl/3/i4oo 20 1700/5 2898 C PTO. -.,030V, 7498 F.C.(?) T/3/11400 21 1700/5 11265 C LRSI /4339 FC? flex. pipe.22.1700/5 6866 C to nozzle;035 W 23 1700/5 2250 C T1/3/1400.035 V_ 24 1700/5 8145 FC L/3/100 LRSII.030.; /S7 3538 FC T1/3/1400 ~,25 -1f \ /700/5 4229 C S-8!6 -Ailoy (vrought) ' 15~0/4 A.... ~~1 1 ~ 'rooz~ ~ s1788 0 o load 183951 C +100/5108 1500/4i.,Piloo -2 to 2657 F A 0..08. P70C. Vfl0 170/0 N5. C 3 o/ 170o0/4 2256 C ~~~~~~~ V....- A-12

~..-W-T-,..~o:(cont). '') ' -2) ~3) (~ ~-. ~.6) Specimen Cross Number Type of NBumber Section Cycle of Cycles -Failure Re 'rks \o/~~~~~~~~~~~~~~a 4 1700/4 2250 C ~ 'V 1600/4 3870 C' 6 1500/4' 2630 C 7-7...>~~71500/4 13280 C 8 1600/4 7497 9 18oo/5 1069- C T /21.~ow.0371 16/180o -l0 1700/5 2426 C T /15 016/18oo 16oo/ 5 5130 C T 1/2150 W i'6 L!6/18oo 12 6180/5 956" To1/2150 w ~0388 6/18oo 13 1700/5 iq + li250..'03 C T ~~~1/2150 W.034 16/18oo 00/3 short

TEST LOG (cont),i (2 (4) (6) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks 14 v 1800/5 11'46 C Tr1/2150 W ~~~~~~.0350 a_ ~~1,6/1800 15 2 1600/4 4600 C T 1/2150 Wi.036 V 16/1800J '" I I~~ ~ ~~ ~~~~ ~ --— ~ ----n~~~ - — II.o03357 1600/4 3620 C TfI/2150 W I Ti6/1-80oo j Average test temp. was 16150 Fo 17 71700/5 1956 C T{1/2150 W.0362 16/1800.0384 6/18oo00 19 34 7 1700/5 2300 T /2150 I.Q345V. j6/8oo00j 20.0331 7 1600/5 3100 C T 1/2150 AX 6/1800oo Average ts t temp. was 16600 F. ~~~- I I -— ~ -~ 1 ~, A-13a

TEST LOG (cont) ' (1)....(2) - ~ ~c'3) (5) (6 Specimen Cross Number':?Type: of Number Section Cycle of Cycles Failure Remarks N-155 Alloy ' (Wrought) I l17j0.15 3764 FC T 1/3/2200- W1 3878 C I 50ol400 o o.0 ~... 4949 2C 2P v 1700/5 3211 C Tl/3/2200 3 7 1700/5 3248 C T 1/32200- I 4 1800/5 1508 T 1//22.~~~~o348\\2/<_,~~~ ~50/1400 5/14oo.o36 /<r —Removed for- c hck;Nb crack,,o1 6 1700/5 3105 C T 1/5/22001W ___________ _- L "50/1400j. i: 2,,_ { a' 0'2: V9 jI 50/1400oo 8 77 1700/' 3195 C Tf1/3/2200 W] 50/1400 039. 9 wK77 1700/5 2888 C Tl/3/2200 W.037 V 4 50/14oo J 10.041 6005 10124 o l//2200 W 50/14oo00 —,::,[ o~o 11 \77 1800/5 2052 C T1/35/2200 W I.o45501400 A-i14

TEST LOG (cont)....2 (5 (' 3)54" (6) Specimen Cross Number Type of Number Section Cycle of Cycles Failure Remarks 12. z 18o0/5 1228 C T/32200 W I 38 l50/1400.o48 50/1400 14.048 1800/5 10495 C /3/2200 I 156 1800/5 990 C Tf1/3/2200 W I. \_8 / 4zoo50/1400 o 774~ 1700/5e~ 1995 C T l/3/2200 W1II.0595 L4010 2077v7 1700/5 2320 C T:53/2200 WI.1.. 1.00/5 1953~ ~./3.00 }/ I 21 \oo/5 5550 C {/3/2200 W II........ I Il 'I.i A-15

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