OAK RIDGE NATIONAL LABORATORY b e operated by Ed UNION CARBIDE CORPORATION @; for the | U.S. ATOMIC ENERGY COMMISSION ORNL- TM- 1341 J30 S S kY | i l-fr EIROET - R 1 | B ELEVATED-TEMPERATURE MECHANICAL PROPERTIES OF WELDS *;‘: IN A Ni=-Mo~-Cr-Fe ALLOY T ;.h' R. G. Gilliland g J. T. Venard X e N R hy - TO THE AEC AND ITS CONTRACTORS ONLY. . NOT APPROVED FOR PUBLIC RELEASE. AVAILABLE l NOTIGE This document contains information of a preliminary nature and was prepared primarily for internal use at the Ook Ridge National Laboratory. It is subject to revision or correction and therefore does not represent a final report. ;_“uwg ._.7__} e mim e e e e L EGAL NOTICE —————— i e e e | | This report was prepared as an cccount of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commissicon: A, Makes any warranty or representotion, expressed or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of | any information, apparatus, method, or process disciosed in this report may not infringe | l privately owned rights; or B. Assumes any liabilities with respect to the use of, or for damages resulting fram the use of l any information, apparatus, method, or process disclosed in this report. i As used in the above, '‘person acting on behalf of the Commission’’ includes any employee or ! contractor of the Commission, or employee of such contractor, to the extent that such employse or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any information pursuant tc his employment or contract with the Commission, or his employment with such contractor. Nt i e G0t By B 8 8 WL et ettt S e R S it Ll | ORNL-TM-1341 Contract No. W-7405-eng-26 METALS AND CERAMICS DIVISION ELEVATED-TEMPERATURE MECHANICAL PROPERTTES OF WELDS IN A Ni-Mo-Cr-Fe ALLOY R. G. Gilliland and J. T. Venard - This paper has been submitted ! to the Welding Journal JANUARY 1966 OAK RIDGE NATIONAL LABORATORY - Osk Ridge, Tennessee : - - operated by - UNION CARBIDE CORPORATION | - - for the - - U.,S, ATOMIC ENERGY COMMISSION | £ .. . /’p ELEVATED TEMPERATURE MECHANICAL PROPERTIES OF WELDS IN A Ni-Mo-Cr-Fe ALLOY¥ R. G. Gillilend and J. T. Venard Metals and Ceramics Division Osk Ridge National Laboratory Oak Ridge, Tennessee ABSTRACT A non-agthardenable; high-strength alloy was developed et the .o Oak Ridge National Laboratory for use as the primary containment mate- rial for the Molten Salt Reactor Experiment\(MSRE). The alloy was molten fluoride salts in thet1100 to 1500°F temperature range, tailored to give good strength, ductility and corrosion resistance to work reported here concerns the elevated-temperature mechanical proper- tles of welds made in thls ‘alloy, known as INOR 8 as represented by ~ . several heats of MSRE-grade material Tensile tests on transverse weld samples in the as-welded and annealed conditions show”a_good combinationrof strength and ductility at temperatures ranging from 70 to 1800°F. Tensile properties of these - weld samples compare favorably W1th those of the base,metal reliEV1ng at 1600 F for 2'hr results in a 1owering of the tensile yield - strength- Creep-rupture tests at llOO 1300 and 1500°F on’ these same , S type specimens show s1gnificant improvement in strength and ductlllty at 1300°F folloW1ng & hydrogen atmosphere stress rellef Both as- - welded and stress-relieved creep-rupture behav1or was as good as the contract with the Union Carblde Corporation. base metel-behav1orp The;nil-ductility temperature, as determined by QEJ , *Research sponsored by the U.S. Atomic Energy Commission under o simulated heat-affected zone thermal cycle tests, was found to be 2300°F. Reasonable recovery of mechanical properties.follows'a simulated welding ecycle with a 2300°F mascimum temperature. INTRODUCTION In order to fully realize the potential of nuclear regctor systems utilizing molten fluoride salts as'fuel, the structural materials must possess adequate combinations of strength, ductility, and corrosion reSistance at temperatures in the 1100-1500°F temperature'?ange. Thé non-age-hardenable nickel-moiybdenum-chromium-irofi élloy, designated as INOR-8 [Ni-17 Mo~7 Cr-5 Fe (wt %) ] is such an'alloy and was the culmina- tion of a comprehensive alloy development and evaluation program carrigd out at the Oak Ridge National L:atboraa:l;o:c';;r.J"‘3 It is now commerciélly available®* and is the primary containment material for the Molten Saxt Reactor Experiment which achieved criticality on June 1, 1965, at Oak Ridge, Tennessee. A vital part of the overall welding study on INOR-8 was the determination of the ‘elevated-temperature mechanical properties of welds. This report summarizes the findings on the mechanical behavior of'welds‘in some of the actual heats of material used in the MSRE. 'MATERIALS, TESTING PROGEDURE AND EXPERIMENTAL RESULTS Transverse samples'machined from 1-in.-thick welds, made under highly restrained conditions were used in the testing. These butt welds were fabricated in the manner illustrated in Fig. 1 and described in earlier work.? The transverse tensile specimens used were of the - ¥ Designated as Hastelloy N by.Stellite Division of Union Carbide Corporation. / ‘ED i | o .l ik . | : o ORNL-LR-DWG 78987 DIMENSIONS IN INCHES ' - FILLET WELDED TO STRONG BACK TO PRODUCE HIGH RESTRAINT WELD T +0 ‘/16_. Yea L Y6 MAX ~ JOINT DESIGN AND WELDING SEQUENCE " Fig. 1 — The INOR-8 high-restraint weldability test specimen,u'sed | - to provide samples for the mechanical properties study. desigrn shown in Fig. 2. The manual gas tungsten arc-welding process was used to fabricate the joints; the filler metal used was of the same nominal composition as the base metal. The INOR-8 material used in this study was taken ffom the stock purchased for construction of the MSRE. The heat numbers and the tests to which each heat of INOR-8 was subjected are tabulated below. Heat Number Type of Test 5055 (Weld Metal) 5057 _ Creep-stress relieved, hydrogen 5060 Creep-as-welded 5062 Tensile-as-welded 5064 Tensile-stress relieved, argon 5067 Creep-stress relieved, hydrogen 5068 Creep-stress relieved, argon 5069 Creep-as-welded 5070 ' Tensile-stress relieved, hydrogen - 5071 -~ Tensile-as-welded 5072 Creep-stress relieved, hydrogen 5073 Tensile-stress relieved, hydrogen 5074 Tensile-as-~welded; creep—stress relieved, argon - 5075 Tensile- stress relieved, argon, Creep-as-welded 5081 Tensile-stress relieved, argon - 5083 Creep-as-welded 5089 Creep-stress relieved, hydrogen 5090 ~ (Weld Metal) The chemical analyses of these heats are presented in Table 1. Note that the filler metal used to fabricate the weld specimens was teken from heat numbers 5055 and 5090. Because of material fabrication schedules, it was necessary to do the welding operations on platé which had the final rolling operation performed normal to the welding direction. This schedule caused the Y materials' inherent stringer line to be located in the plate-thickness - direction and parallel to the fusion line. A typical cross section of — —e—aigh) g e C s ) ORNL-DWG 65-7267 — 3, in.—— - fet- g in.o-| [ 1Y% in.—‘—l S gin.e- - —Ya in. ‘ - - ' 3,‘8in_||||||_ wermaa I | S L L =< X AN }' Vzrin *-! 0.252 + 0.005-in. DIAM | GAGE LENGTH re9e = BTN AMERICAN STANDARD COARSE THREAD— CLASS 2FIT (@) Tra_né#er‘ée Weld Tensile Specimen. 4, in. 3 1/2 m L—O.250-|n. DIAM / - Y4 —20 THREAD | (b) ”;I'-idt.Ddcfility Specim'en. F:Lg. 2 — Transverse tensile spe01men used for hlgh-restraint : VINOR 8 weld evaluations., = - - it Table 1. Chemical Analysis of the INOR-8 Heats } Heat Analysis (wt %)® Number Mo Cr Pe c Si Al Ti B Co v Mn W P S 5055 16.20 17.86 3.76 0.06 0.61 0.06 0.02 0.005 0.10 0.21 0.69 0.03 0.006 0.008 5057 16.80 7.47 3.50 0.05 0.52 0.0L 0,01 0.005 0.09 0.23 0.58 0,02 0.001 0.006 5060 16.20 6.92 4.03 0.07 0.56 0,01 .0.0l 0.004 0.02 0.26 0.46 0.04 0,001 0.00L 5062 16.17 ‘.7.45 3.78 0.04 0.58 0.00 0.01 0.005 0.08 0.24 0.63 ‘0.08 0.001 1 0.006 5064 16.37 7.90 3.59 0.07 0.69 0.0L 0.01 0.005 0.06 0.29 0.59 0.03 0.00L 0.006 5067 17.07 7.23 4,20 0,06 0.43 0.0L 0,01 0,004 0,09 0.30 0.60 0.06 0.00L 0.006 5068 16.50 6.45 4,11 0.05 0.58 '0.0L 0.0L 0.004 0.09 0.27 0.45 0.07 0.003 0,008 - 5069 16.22 6.42 3,93 0.07 0.56 0.01 0.01L 0.006 0.12 0.23 0,52 0.06 0.003 0.009 >070 16.06 6.62 3.93 6.06 0.60 0.04 0.22 0.64 0.03 0.00L 0.008 5071 16.22 7.21 4,35 0.07 0.63 0.0L 0.01 0.004 0,07 0,20 0.65 0.02 0.001 .0.068 5072 15.50 7.03 4.06 0.06 0.57 0.0L 0.02 0,005 0.09 0,27 0.57 0.04_,'0.001 0.012 5073 16.21 6.77 ©3.90 0.05 0.60 0.01 0.0r 0.006 0:07 0.34 0.50 ‘0.03 0.004 0.008 507 16.17 6.77 3.70 0.07 0.62 0.01 0.0pL 0.007 0;67 0.24 0.51 0. 006 —— K 0.02 0.001 [ Heat‘ Analysis (vt %)% W Number | ‘ : Mo Cr- Fe Si Al Ti B Co 5075 16.42 6.7 4.08 5081 16.90 7.7 = 3.56 5083 17.03 751 3.80 5089 16.69 6.78 3.8l 5090 16.22 7.59 4.03 0.06 - 0.06 0.05 - 0.05 0.07 0.57 0.60 0.52 1 0.36 0.56 0.03 0.00 0.01 0.01 0.01 - 0.01 - 0.01 0.01 0.01 0.01 10.001 0. 005 - 0.005 0.004 0.005 0.06 0.07 - 0.10 0.14 0.12 0.28 0.27 0.38 0.39 0.04 0.04 0.05 0.05 0.04 © 0.003 0.003 0.001 - 0.011 “0.001 0.005 0.006 . 0.006 0.012 0.008 ®Balance nickel. the.weld fusion line area is éhown in Fig. 3. Thié fiiew illustrates the | orientation of the stringer formation with respect to tfie fusion line ‘and its pérpendicular orientation with respect to the welding dire¢tion and specimen axis. The transverse weld specimens contained weld metal, hé;t—affected iones, and base metal and were tested at elevated temperatures in sténdard tensile tests (0.03 min-') and in creep tests. Elevated- _ fempérature tensile tests were performed between 600 and 1800°F at 200°F intervalé, and creep testing was dOne at 1100, 1300 and 1500°F. The specimefis were tested in both the as-welded.and stress-relieved conditions, with stress relieving béing performed in bbth argon and -hydrogen atmospheres (2‘hr afi 1600°F). Samples were also machined from the as-received base metal for the'determinationof elevated-température hot ductility after being subjected to simulated heat-affected zone thermal cycles. The room- and elevated-temperature tensile tests were run in air using a standard 12,000-1b capacity hydraulic testing machine at a crosshead speed of 0.05 in./min or a strain rate of 3.33%/min. Stress- strain relationships were obtained using load cell-deflectometer out- puts. Elevafied-temperature tests were performed using a clamshell- - type furnace, in which specimens were allowed a 1/2-hr equilibration period to reach the test temperature. Thé results of these tests for the as-welded and stresé—:elieved conditions are pfesented in Tables 2 and 3 for test temperatures between room temperature and 1800°F. Thercreep tests were run in air using standard lever arm testing machines, and stfain data were obtained through dial-gage extensometers hd T ' i ! i _— )] vone) T . PHOTO 80871 ROLLING DIRECTION i ~PLANE x i i i i Fig. 3 — Typical fusion-line - weld used to provide specimens for Etchant: (r0;, HCl, H,0. 100X, %/}/;//;}/O/TO% - SPECIMEN.- AXIS Y-59814 I 100X o 0.03% INCHES et - | area' of . the .i-in..- thit’:k:-restrained the mechanical property study. TR T Table 2. Short-Time Tension Tests of Reactor Grade INOR-8 in As-Welded Condition Test | Yield Strength | Elongation Temperature - 0.2% Offset '~ Tensile Strength in 1 l/2’in. (°F) (psi) (psi) | (%) Heat | Heat Heat Heat Heat Heat Heat Heat 5062 5071 5074 5062 5071 507 5062 5071 Room 63,100 67,200 66,000 105,700 108,800 91,500 31,5% 27.5% 600 54,000 58,400 52,100 93,900 95,500 84,300 26.5° 27.5° 800 54,300 51,900 52,600 92,100 91,400 82,300 29.0% 29.5 1000 46,400 50,700 47,100 84,100 83,800 179,800 24.0% 26.5% 1200 43,300 49,500 47,600 73,300 73,400 66,800 - 17.5% 17.5% 1400 42,400 46,600 42,100 61,400 58,600 59,600 1.0 8,5% 1600 36,400 37,700 36,400 38,700 38,400 38,200 10.0% 9.5% a . - 1800 21,100 21,900 20,800 21,800 22,400 21,200 17.5 22.0 0T aFaifi.ed in weld metal; S . e Table 3. Sh;;rt-'rime'qzension Tests of Reactor Grade INOR-8 in Stress-Relieved Condition Test = o Yield Strength Elongation Temperature - 0.2% Offset. | Tensile Strength o in 1 1/2 in. (°F) o (pst) B (psi) | (% i A A S . Room 461,0005 O 56,500 97,’_'300- o 102,500 a0 ' 26.5° 0 45,400 43,400 43,400 90,600 90,400 91,800 25.5 - 25.0° 29.0° 800 48,400 39,900 43,500 85,500 87,200 89,000 26.0 275 28.5° 1000 { 39',500f 40,400 40,000 85,500 85,300 84,000 32.0 33.0° 30.5° " 11200 | l39‘,5o_o.- 39,300 40,000 75,800 7d;4oo 74,500 28.5° 20.5. 28.0 1400 36,800 © 37,000 40,000 62,100 57,800 61,000 14.0° 14.0° 14.5 1600 B 34,5‘06 35,000 35,500 39,‘660 40,300 39,500 17.5% 10.0° 11.0 1800 L 21-_I,'50'0" 121,800 21 200 21,900 22,100 21,700 9.0 19.5 28.5° Stress relieved 2 hr at 1600°F, hydrogen Averaged values of Heats 5064, 5075, and 5081 stress relieved 2 hr at 1600°F, argon. ®Failed in weld metal. 12 attached to the specimen grips, A detailed ta‘bulafiion of the average vaiues of the creepQrupture teét results are giveh in Table 4. All heat treatments prior to'testing were'cérried out in either an argon or hydrogen atmosphere. . The specimens were cooled from the annealing temperature by pulling them from the hot zone into the water-cooled end of the furnace muffle. Thermocouples, which weré attached to the speci- mens during the heat treatment, recorded an average cooling rate down to 500°F of épproximately 250°F/min.~The thermal tfeatment uéed, 2 hr at 1600°F, is the standard stress relieving treatment specified for INOR-8 material, | ’ A‘convenient method for measuring overall weldabilifiy is a hot ductility test, which has been developed by Nippes and Savage of Rensselaer Poly'techn-ic’Institute.4 This test synthetically reproduces, in a 1aboratory specimen, the time-temperature cycle experienced'by any selected point in the heat-fiffected zone of afi arc weld. Sampies were taken from all the heats tabulated previously (p. 4) and subjected to this hot ductility test. The results of these tests will be treated in the following sectién. ——y e 1] Average Results of Elevated- Temperature Creep Tests on Table 4} S INCR-8 Transverse Weld Specimens Test Applied _ | | Minimum Creep Temperature Stress - Time to Rupture - Elongation " Rate (°F) (psi) __ _{br) (%) (hrt) ‘ - As o Stress Relieved® As o Stress Relieved® As o Stress Relieved Welded™ Hp Ar Welded™ H» Ar Welded H» Ar 1100 7% oooj:. 1.3 1.7 ‘4.1 13.0 2.6 x10% 1.3 x 1072 1100"f[54 000 197.8 188.3 2.5 8.2 2,3 x 10-% 1,0 x 10~ 1100 49, 000 308.4 570.5 2.2 5.3 1.4 X 10-% 3,2 X 1073 1300 45,000 3.7 6.4 5.5 3.9 8.2 54 4.9 X10°3 7.4 X 10-3 7.0 X 10-3 1300 24,000 158.4 337.8 185.4 3.7 8.8 7.4 1.2 X10-% 1.6 X 10-% 2.2 x 1074 1300 20,000 . 472.3 936.7 452.2 4.6 10.8 3.7 3.5 X10°% 6.6 X 1077 4.4 X 10-% 1500 22,0000 12.7 12.1 '16.9 20.9 5.8 x 107 7.0 x 10-3 1500 13,000 1721 117.5 1.4 9.8 4.8 X 107% 4.4 X 104 1500 10,000 446 9 314.5 8.3 8.1 9.8 x 1075 2,0 x 10 a'Ds,ta from tests on heats tabulated on p. 4 of this report. Stress relieved at 1600°F, 2 hr in atmosphere specified. T =) 14 DISCUSSION AND EVALUATION OF RESULTS Tensile Tests The average tensile properties of épecimens in.the as-welded condition'(heats 5062, 507i and 5074), hydrogen stress-relieved con- dition (heats 5070 and 5073), and argon stfess-relieved condition (heats 5064, 5075 and 5081) are presented in Figs. 4, 5 and 6. These figures show ultimate tensile strength, 0.2% offset yield strength and elongation vs temperature. The scatter bands for wrought metal shown in the figures were teken from earlier work. ? A'qualification'on the ccmbarisons between transverse weld éamfle properties and wrought metal properties shouid be made at this point. figure 7 illustrates specimen afid stringer orientations which were encountered in these two classes of specimens. Note thaf, as previously mentioned, the material fabrication scheduies resulted in the stringers of the transverse weld samples being oriented normal to the stress direc- tion. This stress direction is the y-direction in Fig. 7. The wrought material investigation5 done previously did not inélude specimens cut parallel to the y-direction. The fact that these plates were notrthick enough to yield reasonably large specimens in the y-direction plus the assumption of symmetry of properties sbout the z-axis led to the omission. | Only slight variations in ultimate strengths were observed between the as-welded and stress-relieved tests; although, at the lower testing temperatures these stgengthsrwere,less than those for'the | wrought metal, In the case of the yield strengths noticeable differences existed between the as-welded samples and stress-relieved_samples. As- welded specimen yield strengths were consistently higher than those of =49} g -4 ) 15 'ORNL-DWG 65-6810 120 pANV—— ' 1 I ///// 1 e AS WELDED 2 S o STRESS RELIEVED, = 100 P A | 2 Yoo ////%////)p g Y T, g ° | / z U g 7 z . 4 40 ‘ ! /{Z;} B SCATTER BAND FOR WROUGHT METAL 47, o HEAT NO. 5055 , 5075, AND 5081 ///// | 20 ' '4;'; | I : Y4 o L_V\' RT 600 800 : '_1000 1200 1400 1600 1_800 | - TEST TEMPERATURE (°F) | - " Fig. 4 — Ultimate tensile strength of MSRE INOR-8 transverse weld - specimens. Lo T ST 16 ORNL-DWG €65-6811 40 ,,‘4;///,,!;/ lll A 20 SCATTER BAND FOR WROUGHT METAL 7 2 HEAT NO. 5055, 5075, AND 5081 - - e AS WELDED - a o STRESS RELIEVED, H, § 80 ' a STRESS RELIEVED, Ar 1 ‘ = 60 | < 1 * ® o a0 a .| wul = 3 o o Lo RT 600 800 1000 1200 {1400 1600 1800 TEST TEMPERATURE (°F) Fig. 5 — Yield strength (0.2%) of MSRE INOR-8 transverse weld specimens. ' o ) —A\\ _ — ! I 7 ,/ SCATTER BAND FOR " B / | 46 ' % i ,A:{//, oL IAS \fl\IELDED " R fi ;E | i o STRESS RELIEVED, Hp - | | | & STRESS RELIEVED, Ar N~ ol 1 | 17 ORNL- DWG 65-6812 12)] o RT 600 800 {000 1200 1400 1600 - 1800 o - TEST TEMPERATURE {°F) Fig. 6 Ductility'of MBRE INOR 8 transverse weld specimens. e 18 ORNL-DWG 65-10484 SPECIMEN CUT PARALLEL TO ROLLING DIRECTION L[i:c, z SPECIMEN CUT NORMAL STRINGER To ROLLING DIRECTION ORIENTATION SPECIMEN ORIENTATIONS IN INOR-8 WROUGHT PLATE i ) . -Z BILLET WELDABILITY N_—"" TEST PLATE ROLLING DIRECTION, =2 Dmllgégwgi\l | -h." ' STRINGER ORIENTATION fin""" [ oxio \ TRANSVERSE WELD SAMPLE F'ig. 7 — Sketch showing orientetions of stringers and specimens for wrought metal and transverse weld samples, g i . } —~5) 19 - specimens tested after stress reliev1ng, no difference in annealing atmos- phere was-observed except at room temperature. Yield strengths for trans- . verse specimens in all conditions were‘generally higher than the wrought metal yield strengths. The total elongation data, presented in Tables 2 and 3 and depicted graphically in-Fig;'G, show that the overall ductility of welds is less i . than that observed in the wrought metal. However, this difference is ;_ probably due to the specimen orientation, as previously explained Stress reliev1ng produces 8 general improvement of this property at all test temperatures, with argon prOV1ding a sllghtly better atmosphere than hydrogen. The macrographs of Figs. 8, 9, and 10 illustrate the variations in fracture location with each heat and with test temperature. The as-welded tests in heat 5074 of Fig 8'exhibit failures in the base metal, except at 1400 and 1600°C w1th low ductilities (Table 2) &s compared with the weld metal failures in heat 5062 of Fig. 9. The variation of fracture loca- tions with temperature for the stress-relieved'heat_5070 (Fig. 10) is . ',typical of specimens tested in this condition. On the basis of the data presented above on the ultimate and yield 'strengths the assumption of symmetry in strength properties seems Justified. -”.pThe ductility data however, and in particular the ductility of those spe- = cimens which fractured predominantly in the base metal,,suggest that the -strain-at-fracture properties of INOR-B are not symmetrical about the 7 axis., ' ,T'JT;§ U Metallographic examination was performed on one heat tested in the as-welded condition (5074) and one heat in the stress-relieved condltion (5073). The micrographs shown in Fig. 11A and 118 for the 1800°F tests A 8 20 ‘ " INOR-B; ‘HEAT NO. 5074 oW S il e »?;W ‘ e *"‘Wm g, Fig. 8 — Tensile tests in INOR-8 heat 5074 (as welded) showing location of fracture. no ’ . : . | 8 . _ u - _ . B -m , . , ' ' o W o o o : ) , ‘ - o s , e e o ! . : ) . —r . - o , 6 . ) . . . . - O . , . | | : u, L 2 : . , , o . : - @ - ‘ 1 o : - | : © ) ] | | . . ‘ o m_ . , S oY) m EE . . . , ) s , Lo s D , ; S " ‘ : _ : Lo : ” s o | _ | _ v I “ o & — , . . , | |3 _ et 9 f . Aw,mm,mm . e - . 3 2 S i . - f o ‘ . | * . - y?rmm . g o L , | : & o _ | , 8 . . £ | | , ' . - ) : : o L d) o : . . \ __. " ) R . ) . ’ oy . , . ) - , e ‘ . , . e » , . (foe ' W 1 22 il b 1 A ERT s Fig, 10 — Tensile tests in INOR-8 heat 5070 (stress relleved 2 hr at 1600°F in hydrogen) showing location of fracture. Q - |’- - Y ¥.59827 = 0.035 INCHES N 100X f Y-59811 0.035 IGHES N 100X o - (b) , Fig. 11 — Short-time tensile test failures of INCR-8 material tested at 1800°F in air. A, Heat 5074, as welded; B. Heat 5073, stress relieved 2 hr at 1600°F in hydrogen. Etchant: Cr0s;, HC1, H,O0. 100x. -24 are representative of the base metal failures of all the tensile tests. All failures, whether in the base metal or weld metal, were generally intergranular, As noted by'McCoy,6 mest of the small base metel cracks- appear to fiave been initiated by'cracks'in the'precipitates; Here, as in McCoy's work, the intergranular cracks are predominantly normal te the applied stress with their lengths comparable to the grain diametef. As can be seen in Fig. 11, the cracks are parallel to and exist primarily in the ‘stringer line. Creep-Rupture Tests / s Cfeep-rupture Qata'for specimens in the as-welded and argon or | hydrogen stress-relieved conditions are presented graphically in Figs. 12-15. Average values of rupture time vs applied stress at 1100, 1300 and 1500°F are presented in Fig. 12. These studies indicate that as- welded specimens possess stress-rupture strengths!equivalent to those of the base metal at all test temperatures, Stress relieving, using a hydro- gen atmosphere, created a significant improvement in the creep properties of‘ samples tested at 1300°F. A factor of two improvement was noted in both the time-to-rupture and the total strain propexties when this treatment vas em- ployed (see Table 4). The creep-rupture tests on stress-relieved samplesr at 1100 and 1500°F showed little or no improfiement over as-welded proper-‘ ties.- The curves of Fig. 13 illustrate the stress-temperature relationships necessary to cause rupture in 10, 100 and §OO hr for thesexcomposite speci- mene. ‘The improvement over the as-welded strength at 1300°F by stress relieving in hydrogen at 1600°F for 2 hr is vividly shown in this figure. - The minimum creep fate for tests on ae-fielded and stress-relieved specimens, shown in Figs. 14 and 15, respectively, was generaliy observed. - - ) Vi —~ R4 25 ORNL-DWG 65-6816 SCATTER BANDS - WROUGHT METAL RESULTS: HEATS 5055, 5075, 5081 . 80 —— , ' S —— :6‘////’/////),, ' I ol ! 1 L2279, °C F . \\\\N\\}‘ N IO XS 1T NI, Y, ) Z 40 -..341%?’ 11 ' 200 '//% N AN NN NN NNNNN SRR 7 £ ‘J\‘l\\\ 2 < STRESS (1000 -psi) AN ' ' ; b | i)l 20 — o AT - _ P : 4/2; ) ———AS WELDED%‘%E;; ! 1500 °F §i? /%z% 600°F, 2 e TP 94| |1 | HYDROGEN ANNEAL Y (o L= ARGON ANNEAL . Vi L e 10 100 1000 10,000 'TIME TO RUPTURE' (hr) - Fig. 12. Average creep—rupture data for transverse weld specimens‘ r;:of MSRE INOR-8 in the as-welded and argon and hydrogen stress-relieved . conditlon. .26 ORNL-DWG 65-€813 100 I 80 —— ~_STRESS RELIEVED 1600°F 2hr, H, 60 40 e ...... U O STRESS (1000 psi) 20 S WELDED 10 0O 1200 1300 1400 1500 1600 TEMPERATURE (°F) ' Fig. 13 — Creep-rupture data for transverse weld specimens of MSRE INOR-8 in the as-welded and hydrogen stress-relieved conditions. ——y 4‘§ STRESS (1000 psi) 27 ORNL-DWG €5-6815 DASHED LINES - WROUGHT METAL RESULTS HEATS 5055, 5075, 508t . i ' ”‘ -y \\\ P 100 °F | SRS 60 ol bR N NN : \“4'\\\\\‘\\\\\*% % RS ' : ' | AT TN L= . [ \ - 40 [ \““\ —T ‘ \\\\\1: - 1300 °F R 'L\ ST LrT . . /' 4NN ' RN 20 N \\-QQ‘QS\F | .“%Mi/" 3 N ' ST A ‘ h\\ - \\\ " :\\\\\/./ I L \\\\\\\j - =T 1 || 1800 FustL - | - \\\\i\\ vy 1 : '/ I» \\\ o " 10 AR 10~ 0% 104 003 = 4o - 107! MINIMUM CREEP RATE (he™ 1y Fig. 14 — Mlnimum creep-ra.te data for as-welded transverse weld - specimens in MSRE INOR-8 heats 5060, 5069, 5075 and 5083. 28 _ - ) ORNL-DWG €5-6814 DASHED LINES-WROUGHT METAL RESULTS: HEATS 5055, 5075, 5081 80 N 60 < 2 40 — S , o 1300 °F a W 20 - o o HYDROGEN ANNEAL 0 A ARGON ANNEAL 10-6 1075 1074 1073 o2 o MINIMUM CREEP RATE (hr™") | Fig. 15 — Minimum creep-rate data for stress-relieved transverse weld specimens in MSRE INOR-8. Heats 5057, 5067, 5072 and 5083, annealed in hydrogen, and heats 5068 and 5074, annealed in argon, were held for 2 hr at 1600°F. ‘ (4‘} . e to be‘slightlyrloWEr than that found for wrought metal at all test tem- 29 i peratures and stresses.. One exception to this general cbservation was noted for stress-relieved specimens tested at 1100°F. ‘Metallographic examiuation of several creep-rupture specimens revealed that stress relieving had the general effect of shifting the hrupture,location from the basegmetal to the weld metal., The fracture of the as-welded,specimen in Fig. 16 shows & typical intergranular failure in base metal, with associated graianoundary cracking normal to the applied stress. The appearance of the base metal cracks is very similar " to those discussed above for the short time ten51le tests. The weld | - metal failure of Fig. 16 is typical of creep test fractures observed in .stress-relieved specimens.i"Some'fractures of specimens in this condition -were'observed to occur aloug the weld fusion line, I-Iot Ductility Tests Hot ductility experiments using synthetic heat-affected zone speci- ‘mens revealed the eleveted-temperature nil-ductility p01nt for this mater- ial to be 2300°F as shown 1n Fig 17 The area of‘the heat-affected zone whlch would experience this maximum peak temperature corresponds to & plane calculated to be O, 032 in. from the weld fusion line. 'The curves of this figure indicate that reasonable recovery of the mechanical properties after heating to the nil- ductility temperature was exhibited, although some dam- - age'occurred as afresult:of;the,welding thermal cycle, Since no attempt | was'made'to identify'each»sample‘with a hesat humber,\the obsexved behavior ”is considered to'be"t&piCal'of-MSRE reactor grade INOR-8. As shown in Fig.flS,rno gross grain boundaryiliquatiou has occurred; — however, nhmerous indiVidual,precipitate fiarticles are present which retard W L - T 08T X00! o] S3IHONIGE00 XO0l o] S3HONISE0'0 { u_' '/;. ~ T o < A @ X — e Pm 2 hoo 0 558 LYY e BE T =0 M a8 e g G =R 0O 4 ~¢ B PP e 831.3.” it g gdag o o oA 0K 4P g HDO msrl 8L e B e g -, A s - = o WA SOMR O O 42 N Do e wh LR T O @ o A8 ma o n O o frotd Q L M ul.mtt t.m._u :S $o e o LEERY OO S P emma) - QM Do ~o g | 83 g 85N O o~ - Qo <388 N s H R manae’t O O HE w m o~ W o~ O o o P ey ssmm ™ 31 , S ORNL-DWG 65- 4181R 80 - p— - 0.4 _ - ‘ B | o 60 [\ 60— 03 | —t— \ e o | | TesTeED ON 40 - S - 02 HEATING 7 i ) .\“0 ’ ‘t\fl' : ¥ 2% T 8 20 \ 2 od T 5 1§ TN | S N Fa , ) - : . - ’ -+ . r . o o = o : Z 0 \. 5 oL & 0 'EE\; J =z 80 ~ Seor 0.4 B 5 & 2 - 0 ) o _ . _ o = | 3 60 [— /\ Yeo 1 P 03 ‘ | u 4 B . o _ - = 1 \ & \0\ -] | TESTEDON 40 | a0 —— 0.2 - COOLING FROM “ 1 - \\1_ - N 2300°F -~ . : i ] . ) ¢ ! T - 20 l _ 20 |— \\' 04 /1\\ \‘\ . R S ¢ \ I"'-u 0 o 0l 0L — 1800 2000 2200 2400 1800 2000 2200 2400 ~ 1800 2000 2200 2400 ) TEST TEMPERATURE (°F) | Fig. 17 = Results of hoit‘--'ducrtility tests on MSRE'reactbf-grade INOR-8. The nil-ductility temperature for the material was found to be 2300°F. - SR S I R 32 g 1 Y.56909 0.0035 INCHES 1000X S lo Fig. 18 — Micrograph of the structure of MSRE INOR-8 which has experienced & welding thermal cycle with & peak temperature of 2300°F (NDT). Etchent: H3PO,, Ho0. 1000X. 33 the motion of the grain'boundaries and cause them to be quite irregular. | These boundaries etch rapidly_and.appear quite,broad; indicating that, possibly, an impurity 1ayer'ispresent. Earlier studies have shown that by very rapid cooling from very high temperatureS'(2500°F),,the-pre- cipitate or stringer particles appear to be converted to an 1ntergranular lamellar product Gross - formation of this product throughout the heat- affected zone of INOR-8 welds could cause permanent damage, resultlng in almost certain failure under high restraint. The hot ductility tests -conducted here do not.indicate that this condition is a‘serious problem for the material investigated. - CONCLUSIONS It appears from this.study that the room- and elevated—temperature mechanical properties of welds in INOR-8 compare favorably With the base metal propertlesf' Tensile testing of these transverse specimens .showed_that this material possessed a good combination of strength and .ductility.' Stress relieving.producedthe general effect of'lowering the.0.2% offset yield;strength.. The.creep studies of_as#Welded samples 'indicated that they possessed'stress?rupture properties equivalent to rthose of base metal at all test temperatures. Stressrelieving, uSing- a hydrogen atmosphere, caused a significant improvement in the creep jmproperties of samples tested at 1300°F Heat-affected zone hot ductility '1pexperiments establlshed the nil-ductility temperature for this material o _to be 2300°F, with reasonable mechanical property recovery after o ;experiencing th1s temperature.‘l 34 ACKNOWLEDGMENTS The authors gratefully’acknowledge these people in connection with thé preparation of specimensfandrthe performance of tests: C. W. Dollins, L. C. Williems, H. R. Tinch, E. B. Patton, C. W. Walker, and V. G. Lane. ~The efforts of the Metals and Ceramics Division Reports Office and the ORNL Graphic Arts Department in document preparation is also appreciated. C b-m—d ."fi w 35 REFERENCES 1. Manly, W. D. et al., "Metallurgical Problems in Molten Fluoride Systems," Progr. Nuclear Energy, Tech. and Engr. Series IVQ Vol 2, Pergamon Press (1960). 2. Roche, T. K., The Influence of Composition Upon the 1500°F Creep-Rupture.Strength and Microstrueture of Molybdenum-Chromium-Iron- ' Nickel-Base Alloys, ORNL-2524 (June 24, 1958). 73. Gillilend, R. G. and Slaughter, G. M., "Influence of Minor Alloying Additions in INOR-S Welds," to be published in the WELDING JOURNAL, | 4. Nippes,'E F. et al., "An Investigation of the Hot Ductility of High Temperature Alloye,“ WELDING JOURNAL, 34 (4), 183 to 185 (1955) 5. Venard, J. T., Tens1le and Creep Properties of INOR-S for the Molten-Salt Reactor Experlment ORNL,-TM-1017 (February 1965). 6. McCoy, H. E., Influence of Several MEtallurgical Variables on the Tensile Properties of Hastelloy N, ORNL-3661 (August 1964). " B 'lp‘. ‘n‘-’fl“ .