Astm stp 529 1973

Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized EFFECTS OF RADIATION ON SUBSTRUCTURE AND MECHANICAL PROPERTIES OF METALS AND ALLOYS A symposium presented at the Seventy-fifth Annual Meeting AMERICAIM SOCIETY FOR TESTING AND MATERIALS Los Angeles, Calif., 25-30 June 1972 ASTM SPECIAL TECHNICAL PUBLICATION 529 John Moteff, symposium chairman List price $49.50 04-529000-35 m AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race Street, Philadelphia, Pa 19103 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized ®by AMERICAN SOCIETY FOR TESTING AND MATERIALS 1973 Library of Congress Catalog Card Number: 72-07869 NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Printed in Tallahassee, Fla September 1973 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword The Symposium on Effects of Radiation on Substructure and Mechanical Properties of Metals and Alloys was presented at Los Angeles, Calif., 26-28 June 1972 in conjunction with the Seventy-fifth Annual Meeting of the American Society for Testing and Materials The symposium was sponsored by ASTM Committee E-10 on Radioisotopes and Radiation Effects John Moteff, Materials Science and Metallurgical Engineering Department, University of Cincinnati, served as chairman of the symposium committee, which consisted of C J Baroch, A L Bement, E Landerman, F R Shober, and K M Zwilsky The six sessions were presided over by: (1) L R Steele, (2) H Bohm, (3) J R Weir, (4) T.T Claudson, (5) I P Bell and K.M Zwilsky, and (6) S.D Harkness and C Y Li Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Related ASTM Publications Irradiation Effects on Structural Alloys for Nuclear Reactor Applications, STP 484 (1971), $49.25 (04-484000-35) Analysis of Reactor Vessel Radiation Effects Surveillance Programs, STP 481 (1970), $26.00 (04-481000-35) Irradiation Effects in Structural Alloys for Thermal and Fast Reactors, STP 457 (1970), $36.00 (04-457000-35) Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents Introduction Reactor Vessel Steels—Fracture Behavior Irradiation Strengthening and Fracture Embrittlement of A533-B Pressure Vessel Steel Plate and Submerged-Arc Weld— J A WILLIAMS AND C W HUNTER Radiation-Induced Changes in the Fracture Extension Resistance (R-Curve) of Structural Steels—J R HAWTHORNE AND H.E.WATSON 17 Reactor Vessel Steels—Structure and Impurity Effects Effect of Composition on the Sensitivity of Structural Steel to Irradiation Embrittlement—A E POWERS Discussion On the Radiation Hardening Mechanism in Fe-C-Mn Type Alloys—MILAN BRUMOVSKY 31 39 46 The Role of Some Alloying Elements on Radiation Hardening in Pressure Vessel Steels—N IGATA, K WATANABE, AND S SATO 63 Discussion Property Changes Resulting from Impurity-Defect Interactions in Iron and Pressure Vessel Alloys—F A SMIDT, JR., AND J A SPRAGUE 75 78 Damage-Function Analysis of Neutron-Induced Embrittlement in A302-B Steel at 550 F (288 C)—C Z SERPAN, JR 92 Microstructural Changes—Neutron-Induced Voids and Phases Effects of Microstructure on Swelling and Tensile Properties of Neutron-Irradiated Types 316 and 405 Stainless Steels— K R GARR, C G RHODES, AND D KRAMER Copyright Downloaded/printed University by ASTM 109 Int'l (all by of Washington (University of Discussion Effects of Second-Phase Particles on Irradiation Swelling of Austenitic Alloys—W K APPLEBY AND U E W O L F F Void Formation in Type 1.4988 Stabilized Stainless Steel—K 119 122 EHRLICH AND N H PACKAN 137 Swelling and Tensile Property Evaluations of High-Fluence EBRII Thimbles—R L FISH, J L STRAALSUND, C W HUNTER, AND J J HOLMES 149 Neutron Irradiation Damage in a Precipitation-Hardened Aluminum Alloy—R T KING, A JOSTSONS, AND K FARRELL 165 Discussion A Comparison of the High-Temperature Damage Structures in Accelerator and Reactor Irradiated Molybdenum— 181 B L EYRE AND J H EVANS 184 On the Swelling Mechanism in the Irradiated Boron-Containing Stainless Steel—I V ALTOVSKII, L A ELESIN, P A PLATONOV, AND E G SAVEL'EV 199 Charged-Particle-Induced Voids and Computer Experiments Nickel Ion Bombardment of Types 304 and 316 Stainless Steels: Comparison with Fast-Reactor Swelling Data— W G JOHNSTON, J H ROSOLOWSKI, A M TURKALO, AND T LAURITZEN 213 Void Swelling Behavior of Types 304 and 316 Stainless Steel Irradiated with 4-MeV Ni"^ Ions—S.G MCDONALD AND ANTHONY TAYLOR 228 Discussion Studies of Void Formation in Proton-Irradiated Type 316 and Titanium-Modified 316 Stainless Steels—D W KEEPER, 241 A G PARD, AND D KRAMER 244 Ordered Defect Structures in Irradiated Metals—G L KULCINSKI AND J L BRIMHALL 258 Discussion A Diffusion Model for the Effect of Applied Stress on Void and Loop Growth—J L STRAALSUND, G L GUTHRIE, 272 AND W G WOLFER 274 Attrition and Stabilization of Void Nuclei: Critical Nucleus SizeJ R BEELER,JR., A N D M F BEELER 289 Production of Voids in Stainless Steel by High-Voltage Electrons—F A GARNER AND L E THOMAS Copyright Downloaded/printed University by ASTM 303 Int'l by of Washington (University Discussion Void Formation in Some Nickel-Aluminum Alloys During 20MeV C+^and46.5-MeV Ni*^ Irradiation—J A HUDSON, 324 S FRANCIS, D J MAZEY, AND R S NELSON 326 Mechanical Behavior-Ductility Materials Performance Prediction from Irradiation Test Data —H H YOSHIKAWA High-Temperature Embrittlement of Ferritic and Austenitic Stainless Steels Irradiated up tb 1.6 x 10^^ n/cm^(>0.1 MeV> — P H VAN ASBROECK, M SNYKERS, AND W 337 VANDERMEULEN 349 Effect of Irradiation on the Microstructure and Creep-Rupture Properties of Type 316 Stainless Steel—E E BLOOM AND J O STIEGLER 360 Discussion Ductility of Irradiated Type 316 Stainless Steel—J J HOLMES, 381 A J LOVELL, AND R L FISH 383 Effects of Fast-Neutron Irradiation on Tensile Properties and Swelling Behavior of Vanadium Alloys—R CARLANDER, S D HARKNESS, AND A T SANTHANAM 399 Burst Testing of Zircaloy Cladding from Irradiated PickeringType Fuel Bundles—D G HARDY 415 Mechanical Behavior—Creep, Fatigue, and Tensile Influence of Neutron Spectrum and Microstructure on the Postirradiation Creep Rupture Behavior of an Austenitic CrNi-Ti-B Steel—H BOHM AND C WASSILEW Fatigue Behavior of Irradiated Thin-Section Type 348 Stainless Steel at 550 F (288 C)—H H SMITH AND 437 P SHAHINIAN 451 In-pile Stress Rupture Strength of Three Stabilized Austenitic Stainless Steels—K D CLOSS AND L SCHAEFER Influence of Irradiation on the Creep/Fatigue Behavior of Several Austenitic Stainless Steels and Incoloy 800 at 700 C— 460 C R BRINKMAN, G E KORTH, AND J M BEESTON 473 Discussion Effect of Neutron Irradiation on Fatigue Crack Propagation in Types 304 and 316 Stainless Steels at High Temperatures—P SHAHINIAN, H E WATSON, AND H H SMITH 491 Copyright by Downloaded/printed University of ASTM Int'l (all by Washington (University rights of reserved); Washington) Fri 493 Jan pursuant to 23:06:37 License Agreem Effects of Irradiation on the Tensile and Structural Properties of FV548 Stainless Steel—J S WATKIN, J P SHEPHERD, AND J STANDRING 509 Effect of Neutron Irradiation on Vanadium—J F MclLWAIN, C W CHEN, R BAJAJ, AND M S WECHSLER Copyright Downloaded/printed University by ASTM 529 Int'l (all by of Washington (University of STP529-EB/Sep 1973 Introduction The 1972 Symposium on Effects of Radiation on Substructure and Mechanical Properties of Metals and Alloys was the sixth in a series of related international conferences that have been held biennially The symposium, sponsored by ASTM Committee E-10 on Radioisotopes and Radiation Effects, had the primary objective of providing a forum for a comprehensive review of current technology in the development and evaluation of metallic materials for advanced nuclear reactor designs This was accomplished by bringing together the world's experts in nuclear radiation effects on structural materials In the rapidly expanding field of reactor technology, there is a vital need to bring together those individuals performing laboratory research and conducting theoretical studies of a fundamental nature with reactor designers representing the nuclear industries, nuclear utilities, and government This communication becomes even more critical in view of the requirement for standard procedures of evaluating materials performance and for the establishment of more stringent specifications for reactor structural materials The coupling of the number of atoms that have been displaced from their normal lattice positions in a metal, as well as the rate of atom displacements, due to exposure in a nuclear reactor environment, with changes in mechanical properties and in physical dimensions is rapidly replacing older measures of the radiation-induced transformations, such as the fluence of those neutrons above some specified energy or the nvt parameter In essence, we are now beginning to report our irradiation data on the basis of the primary e/jfec/s—generally denoted as radiation damage, but preferably should be designated as a radiation-induced transformation On the other hand, secondary effects—more appropriately designated radiation-effects, refer to the changes in the physical or mechanical properties that can be measured in the macroscopic sense One of the major problems in radiation effects research is to identify the particular types of atomic scale radiation-induced transformation events that take place in an irradiated specimen from the particular combination or relative magnitudes or both of the radiation effects they produce Conversely, another major problem in radiation effects research is to establish the types and relative magnitudes of the radiation effects that can result from a particular type of radiation-induced transformation This circumstance becomes especially pronounced with the increased use of charged particle irradiations as a means of Copyright by Copyright' 1973 Downloaded/printed University of ASTM by Washington b y AS I M International Int'l (all www.astm.org (University rights of reserved); Washington) Fri pursuant Jan to 530 EFFECTS OF RADIATION ON METALS AND ALLOYS for example, in the phenomena of strain aging and the yield drop In the present paper, the role of interstitial impurities is further elucidated as a result of resistivity, internal friction, and yield stress measurements on oxygen-doped vanadium as a function of neutron irradiation and postirradiation annealing On the applied side, radiation effects on vanadium are of some interest in connection with the possible use of vanadium and vanadium alloys as vacuum envelope material (first wall) in controlled thermonuclear reactors Mechanical reliability in radiation environments is of critical practical importance Interactions between interstitial impurities and radiation-produced defects have a particular bearing on the strength and ductility of irradiated bcc metals Makin and Minter [1] "* showed some years ago that the yield stress of irradiated columbium increases upon postirradiation annealing (radiation-anneal hardening) and the ductility decreases More recent work on irradiated columbium using electrical resistivity [2], internal friction [2], and yield stress measurements [3] indicates that the effects are due to the motion of interstitial oxygen to radiation-produced defect clusters or dislocation loops, which strengthens the clusters or loops as barriers to slip dislocation motion, thereby increasing the yield and flow stresses and decreasing the ductility Interactions between interstitials and radiation-produced defects have been studied in irradiated vanadium using resistivity [4,5], internal friction [5], and mechanical property [6-9] tests In the work of Perepezko et al [4], a resistivity annealing stage was observed at 170 C (338 F or 0.2 Tf„, where T^ is the melting temperature in degrees absolute) upon annealing following irradiation at 60 C (140 F) The annealing activation energy was determined to be about 0.8 eV, and the annealing stage was attributed to the annihilation of intrinsic point defects, such as lattice vacancies However, in the later study of Stanley et al [5], the activation energy for the 0.2 T^ annealing stage was determined to be 1.2 ± 0.1 eV, in agreement with the energies of 1.18 eV and 1.26 eV for the migration of carbon and oxygen [70], respectively In addition, the magnitude of the resistivity decrease was greater for a specimen with greater oxygen and carbon concentrations, and the decrease in resistivity was accompanied by a decrease in internal friction due to superimposed effects of carbon and oxygen Thus, the 0.2 T^ annealing stage was attributed to the motion of interstitial impurities carbon and oxygen rather than to intrinsic radiation-produced lattice defects like vacancies The trapping of interstitial impurities at radiation-produced defect clusters and loops may be expected to alter mechanical properties This is thought to be the origin of the radiation-anneal hardening observed in columbium [1,3,8], vanadium [6-9], molybdenum [11,12], and iron [13] Since radiation-anneal hardening persists to quite high temperatures (for example, to about 600 C (1112 F) or higher in columbium and vanadium), the trapping of interstitials may be responsible for a large fraction of the radiation hardening observed as a consequence of elevated-temperature irradiation Mechanisms of radiation hardening and radiation-anneal hardening have been postulated, based on a dispersed4 The italic numbers in brackets refer to the Ust of references appended to this paper Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized MCILWAIN ET AL ON NEUTRON IRRADIATION ON VANADIUM 531 barrier model [14] The hardening in such a model depends on the density and size distribution of the barriers (defect clusters and loops) In the case of columbium, the radiation-anneal hardening constituted an almost twofold increase in yield stress, but the density and size distribution of barriers observed by transmission electron microscopy (TEM) were only slightly changed Thus, on the assumption that the barriers responsible for radiation hardening are those observed by TEM, it was concluded that the radiation-anneal hardening is due to the strengthening of the radiation-produced barriers as a result of the trapping of interstitial impurities and not to a change in the density or size distribution of the barriers [3,14] These matters relating to the influence of interstitial impurities on radiation hardening in bcc metals were reviewed at a recent conference [15,16] The foregoing discussion emphasizes the importance of identifying the unique influence of each particular interstitial impurity on observed radiation effects In the work described in the following, a special attempt was made to control and determine the interstitial impurity content and to isolate the particular effect of oxygen Resistivity, internal friction, and yield stress measurements were performed as a function of neutron irradiation and postirradiation annealing for specimens containing various oxygen concentrations As is described, further evidence is accumulated linking the annealing stage at about 0.2 T^ to the trapping of interstitial oxygen, which produces an increase in strength and a decrease in ductility Experimental Procedure Specimen Preparation Resistivity, internal friction, and tension specimens were prepared from three lots of U S Bureau of Mines vanadium Samples were arc melted, swaged, and polished to form resistivity and internal friction specimens of 0.076 cm diameter and tension specimens of 0.2 cm gage diameter and 2.54 cm gage length Impurity concentrations of the final material after loading with oxygen are given in Table Irradiations The resistivity and internal friction specimens were irradiated in the cryostat facUity of the Ames Laboratory Research Reactor (ALRR) at -190 C (-310 F) to neutron fluences' of 3.5 x 10*'', 1.2 x 10'*, and 2.7 x 10'* neutrons(n)/cm^ (E > MeV) The tension specimens were irradiated in contact with the heavy-water coolant in the central thimble of the ALRR at 106 C (223 F) to a fluence of 1.2 x 10' * n/cm^ (E > MeV) Measuring Procedures Low-frequency internal friction measurements were performed from 21 to 350 C (70 to 662 F) in an inverted torsion pendulum under a helium atmosphere Fluences are given in terms of neutrons with energies above MeV For fluences of neutrons with£'> 0.1 MeV, indicated values should be multiplied by 1.5 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 532 EFFECTS OF R A D I A T I O N ON M E T A L S A N D A L L O Y S • ^ O • * 00 \ D 00 ^ H O O O O O O O ^ ^ o o O O (N W-) o to ^ " o o § ^ S2 e (N (N ;;svv r^ o o o O o o o ^ ^O CO o O O O (N (N -^ ;;vvv a o m ' o "o i^ lo CO o r^ o lo Đ ã^ \D ãS V 'vv rr\ I o o r) O i/^ O ^ Tf — ? ^ lO V « O IT) IT) lO ' - ^ , , ( N (N w w £ < O o vo li-^ in V •vv S SI I u T3 • « o gou zx ^fc Z < S M Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized MCILWAIN ET AL ON NEUTRON IRRADIATION ON VANADIUM 533 or vacuum A standard four-probe technique was used for resistivity measurements in liquid nitrogen or liq^iid helium Annealing was done in baths of Freon and liquid nitrogen, methanol and dry ice, and silicone oil Tension tests were performed on an Instron machine at room temperature Annealing of tension specimens was carried out in a dual-chamber, high-vacuum furnace Results One-hour anneals at intervals of 15 C (27 F) were carried out at temperatures from - 150 to 220 C (- 238 to 428 F) After each anneal, a resistivity measurement was made at -196 C (-321 F) From these data derivative curves were obtained which delineate the annealing spectra Figure shows the derivative ANNEALING -300-200 -100 T TEMPERATURE (°F) 100 200 300 400 500 0.007h HIGH OXYGEN * = 2.7)( lO'^n/cm^ (E>IMeV) 0.006 0.005 0.004 C3 a 0.003 0.002 0.001 0.000 -100 ANNEALING 100 200 TEMPERATURE (°C) FIG -Derivative curve for resistivity as a function of isochronal annealing temperature for a high-oxygen vanadium specimen irradiated to 2.7 x 10^ * neutrons/cm''- /Ti> MeV) at -190 C (-310 F) Annealing time, h; annealing temperature interval, 15 C (27F); temperature of measurement, -196 C (-321 F) curve for a high-oxygen specimen irradiated to 2.7 x 10' * n/cm^ {E> I MeV) Three major peaks are shown, but only the 0.2 r „ peak at about 170 C (338 F) is treated in the present paper This peak appeared for all three oxygen levels and all three neutron fluences Figure shows the derivative anneaUng curves from 80 to 220 C (176 to 428 F) for the three oxygen levels and three neutron fluences Several features of these curves are apparent: (a) The peak height increases with increasing neutron fluences for similar oxygen concentrations, {b) The peak height increases with increasing oxygen concentration for the same fluence (c) The peak temperature decreases with increasing neutron fluence for each concentration level It is well established that the height of a particular internal friction peak (Snoek damping peak) is directly proportional to the concentration in solid Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz 534 EFFECTS OF R A D I A T I O N ON METALS A N D A L L O Y S ANNEALING TEMPERATURE (°F) 200 250 300 350 400 450 FAST NEUTRON FLUENCE „ ^ ,„I8 , (E>IMeV — 2.7 X10 n/cm — l.2i(lo'^n/cm^ 3.5xlo'^n/cm^ a < 0.000 ANNEALING TEMPERATURE (°C) FIG 2-Derivative curves for resistivity as a function of isochronal annealing temperature for high-, medium-, and low-oxygen vanadium specimens irradiated at -190 C (-310 F) to indicated neutron fluences Annealing time, h; annealing temperature interval, 15 C (27 F); temperature of measurement, -196 C (-321 F) solution of a given interstitial impurity To further establish the role of oxygen in 0.2 Tm annealing, a series of resistivity and internal friction measurements were made upon isothermal annealing at 175 C (347 F) The frequency of the torsion pendulum for the internal friction measurement was adjusted to about 0.6 Hz to correspond to the damping peak due specifically to oxygen In order to calibrate the damping peak height or relaxation strength to oxygen concentration in solid solution, the relaxation strengths of a series of specimens of varying oxygen contents (as determined by vacuum fusion analysis) were determined, and a calibration factor of 0.18 per atomic percent oxygen was obtained The corresponding value cited by Stanley et al [5] was 0.11 and 0.15 per atomic percent oxygen; they also indicate other values from the literature ranging from 0.098 to 0.168 per atomic percent oxygen (excluding the value of 0.55 per atomic percent oxygen [10], which seems anomalously high) Then, the resistivity contribution of oxygen at 4.2 K and 77 K was determined by measuring the resistivities (of the same internal friction specimens discussed in the foregoing) in liquid helium and liquid nitrogen, respectively Specific resistivity contributions of 5.0 ± 0.1 and 5.4 ± 0.1 M^-cm per atomic percent oxygen were obtained at 4.2 K and 77 K, respectively, which compare favorably with the value of 5.7 ;uJ2-cm atomic weight percent oxygen measured by Horz et al [17] at IOC (50F) Figure shows the decrease in oxygen concentration Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WICILWAIN ET A L ON N E U T R O N I R R A D I A T I O N ON V A N A D I U M 10 100 1000 100 1000 535 10,000 10,000 100,000 ANNEALING TIME (SEC) FIG i—Decrease in oxygen concentration in solid solution in vanadium deduced from internalfrictionat about 0.6 Hz and resistivity measurements at -269 C (-452 F) as a function of isothermal annealing time at 175 C (347F), following irradiation to 2.7x 10^^ neutrons/cm^ (E> MeV) at-190 C (-310 F) upon post-irradiation annealing at 175 C (347 F) as deduced from the observed decreases in internal friction and resistivity It is seen for the high-oxygen vanadium that the two curves agree quite well over the entire stage, implying that the resistivity annealing is due solely to the removal of oxygen from solid solution To determine the activation energy for the postirradiation annealing process responsible for the 0.2 7"^ stage, a series of isothermal resistivity annealing runs was conducted at increasingly higher temperatures, namely, at 143.6, 158.9, 174.2, and 189.6 C (290.5, 318.0, 345.6, and 373.3 F) for the high-oxygen material Using the ratio-of-slope method [75], we determined the activation energy to be 1.1 ± 0.1 eV For comparison, activation energy for oxygen migration in unirradiated vanadium was also determined by internal friction measurements using the frequency-change method employed by Powers and Doyle [10] The value obtained was 1.23 ± 0.04 eV for high-oxygen material and 1.23 ± 0.07 eV for medium-oxygen material In connection with the yield stress measurements, isochronal anneals were carried out on separate irradiated and unirradiated specimens for one hour at temperatures from 120 to 510 C (248 to 950 F) The tension tests were Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions author 536 EFFECTS OF RADIATION ON METALS AND ALLOYS performed at room temperature at a strain rate of 1.7 x 10"* per second The results are summarized in Fig 4, which shows the difference between lower yield stresses* for irradiated and unirradiated specimens versus isochronal annealing ANNEALING I 300 TEMPERATURE (°F) 500 700 900 o o o 100 200 300 ANNEALING 400 500 TEMPERATURE (°C) FIG ^-Difference in yield stress versus isochronal annealing temperature for irradiated and unirradiated vanadium with low, medium, and high oxygen concentrations Irradiation fluence and temperature, 1.2 x 10^^ neutrons/cm'^ (E > MeVj at 106 C (223Fj Annealing time, h; test temperature, 24 C (75 Fj; strain rate, 1.7 x W^ s"' temperature for the three oxygen levels The unirradiated specimens were largely unaffected by the anneals Figure shows that the hardening due to irradiation at 106 C (223 F) increases with increasing oxygen concentration It is also apparent that the radiation-anneal hardening increases with oxygen concentration Discussion In the earlier attempts to interpret the origin of annealing stages in irradiated bcc metals, such as those shown in Fig 1, emphasis was placed on the role of intrinsic radiation-produced defects However, more recent work [2,5] indicates that interstitial impurities play an important part, and this seems to be borne out in the present investigation As described above, the activation energy of the highest temperature annealing peak at 0.2 Tf„ in Fig wa§ determined to be 1.1 ±0.1 eV, in agreement with the value of 1.2 ± 0.1 eV observed by Stanley et al [5], though in serious disagreement with the value of 0.79 ± 0.09 eV given by 'Perepezko et al [4\ The annealing activation energy of about 1.2 eV suggests that the annealing stage is due to interstitial oxygen, since the migration energy of oxygen in vanadium as determined directly by internal friction measurements was 1.23 eV in this study and 1.26 eV by Powers and Doyle [10] Further evidence for linking the 0.2 Tf„ annealing peak in vanadium to oxygen impurity atoms is seen in Fig The magnitude of the annealing stage is shown to increase with increasing oxygen concentration and increasing neutron fluence * For cases where no yield drop was observed, the 0.2 percent offset yield stress was used Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized MCILWAIN ET AL ON NEUTRON IRRADIATION ON VANADIUM 537 There is some suggestion of a decrease in peak temperature with increasing oxygen concentration, which may be due to the more rapid arrival of oxygen atoms at the trapping sites, where they are effectively removed from solid solution The trapping sites are assumed to be the defect clusters and dislocation loops produced upon irradiation Thus, it is also to be expected that the peak temperatures will shift downward with increasing neutron fluence, and this is also shown in Fig Still further association of oxygen with the 0.2 r „ annealing stage in vanadium stems from a comparison of the postirradiation annealing of resistivity with that of internal friction, which is specifically due to oxygen in solid solution As seen in Fig 3, the decreases in oxygen concentration in solid solution during annealing at 175 C (347 F) as deduced from decreases in resistivity and internal friction are in quite good agreement, especially for the highest initial oxygen concentration The removal of oxygen from solid solution in the high-oxygen material appears to reach a limiting value of about 450 atomic ppm oxygen, which corresponds to only about 20 percent of the total initial concentration This indicates that for high-oxygen vanadium the removal of oxygen from soHd solution is not limited by the amount initially present but by the availabiHty of trapping sites (radiation-produced defect clusters) Since the total oxygen concentration in the low-oxygen material (160 to 225 atomic ppm) was lower than the 400 atomic ppm apparently necessary to saturate the traps, the process in this material was perhaps limited by the total available oxygen On this basis, the medium-oxygen material (450 to 640 atomic ppm oxygen) would appear to be close to tlje borderline between being oxygenlimited or trap-limited In any case, the rapidity with which oxygen is removed from solid solution should increase with increasing oxygen concentration, as seen in Fig However, the foregoing discussion indicates that the amount of oxygen removed for a particular annealing time at temperature is not expected to bear a simple relationship necessarily to the total initial concentration The essential thrust of our interpretation of the 0.2 T^ annealing stage is in terms of interstitial impurity migration to radiation-produced defect clusters Interpretations in terms of the motion of intrinsic radiation-produced defects to interstitial impurity atoms are also possible For a review of the various viewpoints, the reader is referred to the proceedings of a conference [19] and to a recent exchange of short communications [20,21,22] A brief mention of the two lower-temperature peaks in Fig is in order It is tempting to consider the possibility that the lowest temperature peak at about -105 C (-157 F) may be due to hydrogen As a first approximation, we may expect this peak to correspond roughly to the same E/T ratio (E, annealing activation energy; T, absolute peak temperature) as for the highest temperature peak for which £" = 1.2 ± 0.1 eV and T=443 K This predicts an energy of 0.45 ± 0.04 eV for the lowest temperature peak in Fig at r = 168 K Activation energies for diffusion of hydrogen in vanadium have been reported to be as high as 0.39 eV [23], although lower values have also been given; for example, 0.28 eV [24], 0.12 eV [25], and 0.05 eV [26] As for the middle peak in Fig 1, it Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 538 EFFECTS OF R A D I A T I O N ON M E T A L S A N D A L L O Y S may be associated with the anneaUng of lattice vacancies, but unfortunately no information is available concerning the vacancy migration energy for vanadium Since the tension specimens were irradiated at 106 C (223 F), the impurity atom and defect motions responsible for the two lower temperature peaks would be occurring during irradiation The defect structure is therefore expected to be somewhat different for the two cases However, since the origins of the lower-temperature peaks are quite uncertain, it does not appear fruitful at this time to speculate further on the nature of the low-temperature defect structure However, the defect structure at room temperature and upon annealing to elevated temperatures has been studied by TEM techniques [7,27,28] The defect clusters are observed to increase in size and decrease in density upon postirradiation annealing The larger defect clusters were found by diffraction contrast analysis to be interstitial in nature by Rau and Ladd [27] and Smidt [7] but vacancy in nature by Elen [28] As concerns the results on radiation hardening, Fig shows at the extreme left that the highest oxygen specimens experience about twice the amount of hardening upon irradiation at 106 C (223 F) as the lowest oxygen specimens It would appear, therefore, that some trapping of oxygen at defect clusters and loops took place upon irradiation, which increased the strength of the clusters and loops as barriers to slip dislocations While it may seem strange that trapping would take place at irradiation temperatures below that for appreciable mobility of the interstitial solute, similar observations have been made for oxygen in irradiated columbium [3] and nitrogen in irradiated iron [13] Upon postirradiation annealing, a further radiation-anneal hardening takes place, which persists to temperatures at least as high as 400 C (752 F) Above 400 C some recovery toward the pre-irradiation strength is apparent, especially for the high-oxygen specimens, but the anneals have not been carried to high enough temperatures at this writing to delineate the recovery clearly The yield stress values in Fig exhibit a fair amount of scatter, which is believed to be due largely to surface corrosion on the vanadium specimens as a consequence of their contact with reactor coolant heavy water during irradiation To check that no oxygen was absorbed as a result of the contact with reactor coolant water, irradiated samples (pieces from broken tensile bars) were submitted for vacuum fusion chemical analysis The results gave 56 ± weight ppm (3 samples), 206 ± 14 weight ppm (4 samples), and 656 ± 22 weight ppm (2 samples) for low-, medium-, and high-oxygen material, respectively We can see from Table that no significant intake of oxygen occurred It maybe deduced also that no significant oxygen intake is to be expected The parameters for diffusion of oxygen in vanadium are 0.0246 cm^/s for the pre-exponential factor and 1.28 eV for the diffusion activation energy [29] Hence, at the temperature of irradiation, 106 C (223 F), the diffusivity is calculated to be 2.18 x 10'^' cm^/s Thus corresponding to the irradiation time of about x 10* s, we calculate a penetration of x = 2JDt= 1.3x10'^ mm Copyright by ASTM Int'l (all rights reserved); Fri Jan Downloaded/printed by University of Washington (University of Washington) pursuant to 23:06:37 License EST 2016 Agreement No further MCILWAIN ET AL ON NEUTRON IRRADIATION ON VANADIUM 539 which is neghgible compared to the gage diameter of mm The scatter in experimental results notwithstanding, Fig shows a clear tendency for radiation-anneal hardening to increase with increasing concentration of oxygen interstitial solute concentration In connection with the use of bcc metals—particularly vanadium and columbium—in radiation environments in controlled thermonuclear reactors, it will be of interest to understand more fully the origin of this radiation-anneal hardening Higher fluence and higher temperature irradiations will be particularly relevant, as well as experiments to determine the degree of embrittlement that may accompany the hardening, as indicated in earlier work [1,6] The present work indicates that careful control should be exercised over interstitial impurities in the materials to be investigated Summary Resistivity measurements on oxygen-doped vanadium specimens irradiated near liquid nitrogen temperature and annealed at - 150 to 200 C(-238 to 428 F) indicate an annealing stage at 0.2 T„ (170 C or 338 F) Combined with internal friction results, these measurements show that the stage is due to the trapping of interstitial oxygen at radiation-produced defect clusters and dislocation loops This conclusion is based on the following: (a) the annealing activation energy was observed to be 1.1 ±0.1 eV, close to the value of 1.23 eV measured by internal friction techniques for oxygen migration; (b) the magnitude of the stage increased with increasing oxygen concentration; and (c) the decrease in oxygen concentration deduced from isothermal resistivity annealing measurements was in substantial agreement with the decrease in oxygen concentration deduced from corresponding measurements of the internal friction due to oxygen Postirradiation isochronal resistivity annealing measurements also exhibit annealing stages at - 105 C (- 157 F) and 30 C (86 F) The origins of these stages are not well established, but hydrogen is suggested as the annealing species for the -150 C stage Yield stress measurements upon irradiation at 106 C (223 F) indicate greater radiation hardening for higher-oxygen specimens, which suggests some trapping of oxygen at radiation-produced defect clusters and loops during irradiation Upon postirradiation annealing, a further increase in yield stress is observed whose magnitude is greater for higher interstitial impurity concentrations From earlier work, it is known that radiation-anneal hardening may be accompanied by decreases in ductility, which emphasizes the practical significance of interstitial impurities in bcc structural metals and alloys used in elevated-temperature radiation environments Acknowledgments The assistance of T A Sullivan of the Bureau of Mines, Boulder City, and N J Carson of the Argonne National Laboratory in providing the vanadium starting stock is greatly appreciated We also wish to thank T E Scott and D T Peterson of Ames Laboratory for helpful comments concerning the diffusion of hydrogen and oxygen in vanadium Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 540 EFFECTS OF RADIATION ON METALS AND ALLOYS References [I] [2] [3] [4] [5] [6] [7] [S] [9] [10\ [II] [72] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] Makin, M J and Minter, F G.,ActaMetallurgica, Vol 7, 1959, pp 361-366 Williams, J M., Brundage, W E., and Stanley, J T., Metals Science Journal, Vol 2, 1968, pp 100-104 Ohr, S M., Tuclcer, R P., and Wechsler, M S., Physica Status Solidi, Vol A2, 1970, pp 559-569 Perepezko, J H., Murphy, R F., and Johnson, A K., Philosophical Magazine, Vol 19, 1969, pp 1-6 Stanley, J T., Williams, J M., Brundage, W E., and Wechsler, M S., Acta Metallurgica, VoL 20, 1972, pp 191-198 Smolik, G R and Chen, C "H., Journal of Nuclear Materials, Vol 35, 1970, pp 94-101 Smidt, F K.,Radiation Effects, Vol 10, 1971, pp 205-214 Venetch, J., Johnson, A A., and Mukherjee, Y^., Journal of Nuclear Materials, Vol 34, 1970, pp 343-344 Bocek, M., Bohm, H., and Schneider, W., Journal of Nuclear Materials, Vol 40, 1971, pp 249-270 Powers, R W and Doyle, M V., Journal of Applied Physics, Vol 30, 1959, pp 514-524 Wronski, A S: and Johnson, A A., Philosophical Magazine, Vol 8, 1963, pp 1067-1070 Downey, M E and Eyre, B L., Philosophical Magazine, Vol 11, 1965, pp 53-70 Ohr, S M., Wechsler, M S., Chen, C W., and Hinkle, N E., "Radiation Hardening and Radiation-Anneal Hardening in Body-Centered Cubic Metals," Second International Conference on Strength of Metals and Alloys, American Society for Metals, Metals Park, Ohio, 1970, pp 742-746 Tuckei,V< 'P.andV/echs\er,M.S.,Radiation Effects, Vol 3, 1970, pp 73-87 Wechsler, M S., "Mechanical Properties and Defects in Refractory Metals," Defects in Refractory Metals, R de Batist, J Hihoul, and L, Stals, Eds., Studiecentrum Voor Kernenergie, SCK/CEN, Mol, Belguim, 1972, pp 257-273 Wechsler, M S., "Impurity-Defect Interactions and Radiation Hardening in BCC Metals," Defects in Refractory Metals, R de Batist, J, Nihoul, and L Stals, Eds., Studiecentrum Voor Kernenergie, SCK/CEN, Mol, Belguim, 1972, pp 235-240 Hbrz, G., Gebhardt, E., and Dlirrschnabel, W., Zeitschrift furMetallkunde, Vol 56, 1965, pp 554-560 Damask, A C and Dienes, G i., Point Defects in Metals, Gordon and Breach, New York, 1963, p 147 De Batist, R., Nihoul, J., and Stals, L., Eds, Defects in Refractory Metals, Studiecentrum Voor Kernenergie, S.C.K./C.E.N., Mol Belguim, 1972 Johnson, A A., Scripta Metallurgica, Vol 7, 1973, pp 1-6 Wechsler, M S., Williams, J M., and Stanley, J T., Scripta Metallurgica, Vol 7, 1973, pp 7-14 Johnson, A A , Scripta Metallurgica, Vol 7, 1973, pp 15-19 Butera, R A and Kofstad, P., Journal of Applied Physics, Vol 34, 1963, pp 2172-2174 Veleckis, E., Ph.D thesis, Illinois Institute of Technology, 1960 Kley, W., Peretti, J., Rubin, R., and Verdan, G., ProceedingsBrookhaven Symposium on Inelastic Scattering of Neutrons, BNL-940, Brookhaven National Laboratory, New York, 1965 Schaumann, G., Vblkl, J., and Alefeld, G., Physica Status Solidi, Vol 42, 1970, pp 401-413 Rau, R C and Ladd, R L., Journal of Nuclear Materials, Vol 30, 1969, pp 297-302 Elen, J D., "Direct Observation of Damage in Neutron Irradiated Vanadium," RCN-96, Reactor Centrum Nederland, Petten, 1967 Schmidt, F A and Warner, J C , Journal of less Common Metals, Vol 26, 1972, pp 325-326 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP529-EB/Sep 1973 INDEX Activation energy, 56, 145, 196, 206, 291,318,468,537 Aging, 67, 116, 167, 328, 468, 474, 512,523,530 Aluminum, 63, 175, 181, 272, 326, 353 Aluminum alloy 6061, 165 Anneal, 39, 57, 64, 76, 78, 109, 119, 125, 138, 150, 165, 177, 209, 244, 281, 291, 366, 373, 383, 419,438,512,533,535 Austenitic alloys, 122, 437, 451, 460, 473 B Boron,199,448 Bubbles, 141, 203, 319, 377, 394, 523 Burst test, 415, 418 Carbon, 46, 63, 238, 242, 253, 294, 317,328,530 Cavities, 141, 178,377 Chromium, 63, 375,400,403,413 Cladding, 122, 138, 228, 349, 360, 415,416,426,438,451,470 Clusters, 32, 40, 65, 76,83, 142, 181, 188,291,413,457,531 Cold working, 77, 109, 138,165, 221, 235, 249, 287, 360, 382, 419, 425,447,463 Columbium, 65, 138, 263, 426, 438, 509,516 Composition, effect of, 31,46, 63,71, 75, 78, 188, 353, 355, 375, 400,413,448,470 Compression test, 81 Computer analysis, 95, 290, 391, 474 Copper, 63,78,160 Cracks, 7, 17, 173, 354, 369, 394, 452, 464,493 Creep, 156, 178, 181, 275, 360, 368, 381, 383, 388, 391, 394, 437, 460,473,485,491 D Damage function, 92, 97, 337, 339, 341,342,344 Defects, 119,425 Denuded zones, 231, 304, 324 Diffusion, 55, 145, 187, 199, 274, 279, 300,319 Dilatometry, 200 Dislocations, 58, 85, 111, 131, 138, 155, 170, 188, 203, 230, 261, 275, 304, 331, 360, 382, 410, 426,433,470,509,522,529 DPA models Half Nelson, 184 Kinchin and Pease, 93, 102, 138,245 Ductility, 162, 177, 181, 355, 361, 381, 383, 391, 395, 423, 433, 444, 457, 475, 491, 502, 506, 512,528,530 Electrical restivity, 185, 530 Embrittlement, 6, 31, 39, 61, 63, 76, 78, 92, 119, 346, 349, 354, 400,449,451,460,492,506 541 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Copyright' 1973 b y AS FM International www.astm.org Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 542 EFFECTS OF R A D I A T I O N ON M E T A L S A N D A L L O Y S F Indium, 181 Internal friction, 39, 64, 400, 407, 530 Interstitials, 37, 39, 75, 89, 113, 134, 181, 188, 232, 254, 261, 272, 275,319,324,360,530 Iron, 40, 51,76,79,85, 160,290,319 Irradiation Electron, 303, 430 Ion, 134, 184, 187, 213, 228, 236, 244,259,303, 317, 326,327 Neutron, 6, 17,31, 50,64,92, 135, 147, 165, 184, 185, 213, 228,241,311, 326, 439, 451,460,473,493, 509,529 Grain boundaries, 83, 127, 167, 178, 203, 231, 258, 304, 354, 37L 394,438,469,506,509,523 Lithium, 448 H Loops, 39,75,84, 113,134,155,170, 181, 187, 203, 230, 252, 258, Hardening, 14, 39, 46, 63, 71, 75, 79, 274, 278, 306, 331, 425, 527, 116, 172, 351, 396, 400, 429, 531 496,526, 530 Dispersion, 353, 446 M PeTcipitation,81, 165 Work, 81, 181,455,514 Manganese, 46 Hastelloy-X, 122 Microhardness, 50 Helium, H I , 119, 134,176,183,185, Microscopy 216, 230, 243, 244, 245, 292, FIM,77, 194 304, 332, 342, 349, 353, 377, Optical, 111, 369, 423, 469, 394,400,448,451,506,523 523 Hydrogen, 134, 176, 183,400,416 SEM, 150,371 TEM, 65, 76, 79, 84, 111, 122, I 140, 160, 167, 181, 187, 200, 217,229,245, 258, Immersion density 111, 122, 140, 304, 327, 330, 362, 373, 152,166 400, 419, 425, 444, 469, Impact testing, 53, 93 511,516,531 Impurities, 75, 78, 85, 134, 183, 185, Microstructure, 47, 109, 111, 131, 289,290,326,392,410,530 166, 167, 181, 188, 232, 243, Incoloy800, 123,473 248,259,276,360,401,437 Inconel625, 123 Mild steels, 75 Inconel 600, 135 Fatigue, 451, 473, 475,485,491,493 Fe-C-Mn alloys, 46 Fe-Cr alloys, 63, 66 Fe-Cu alloys, 63, 68 Fe-Mo alloys, 63, 66 Fe-Ni alloys, 63,65 Fracture Mode, 114, 159, 165,173,354, 361,369,393 Resistance, 17, 354 Strength, 170 Toughness, Fuel fabrication, 416 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized INDEX Molybdenum, 63, 160, 184,263,300, 375,448 N Nickel alloys, 225, 356 Highnickel, 123,131 Ni-Al alloys, 326 328 Nickel, 63, 123, 131, 160, 213, 225, 238, 241, 259, 263, 275, 292, 317, 324, 326, 327, 349, 353, 356 Nimonic alloys, 327, 330 Nitrogen, 32, 39,63,75,187 O Ordered structure, 193,258,262, 272, 292,317 Oxygen, 75,319,400,492, 530 Percipitates, 33, 67, 75, 111, 122, 138, 165, 169, 233, 252, 258, 259, 275, 308, 328, 355, 360, 382,392,412,443,468,516 Performance, 337 Phosphorus, 41,78 Point defects, 56, 65, 75, 239, 276, 304,457, 530 Powder metallurgy, 351, 357 Pressure vessel, 17, 31, 39,46, 63,78, 102 543 215, 228, 317, 337, 384, 409, 471, 474, 491, 496 ETR,6,338,471 FFTF,287 FR 2,437,447 FTR, 155,360 GETR, 338 Herald R, 510 HFIR, 166 JH-IA Army PWR, 452 JRR-2, 64 K-East P, 97 LITR, 97 LMFBR, 109, 122, 149, 287, 303, 339, 360, 399, 473, 492 MTR, 181 San ONOFRE PR, 97 SNR,471 WR-S, 50 UCRR, 18,81,97 Yankee PR, 97,99 Recovery, 40, 57, 65, 76, 366, 381, 463 Selenium, 259 Silicon, 63,169,181 Simulation, of neutron irradiation, 312 Slip, 117,159,433 Softening, 119 Stainless steels 304 SS, 123, 125, 138, 149, Quenching, 66, 75 213, 228, 230, 241, 253, 304, 343, 347, 361, 382, 392,438,473,493 Reactors 304L SS, 473 ATR,81,496 316 SS, 109, 119, 125, 138, BigRockPR,97,100,102 213, 221,228, 234,244, BR2,64,437,439,471 247, 249,304,360,381, CTR, 399 383, 438, 473, 485, 493 DFR, 137, 184, 317, 381,510 316LSS,304 OMTR,510 316SS, 228 EBR-II, 110, 122, 138, 149, 321 SS, 324 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 544 EFFECTS OF RADIATION ON METALS AND ALLOYS 347 SS, 125, 130 U 348 SS, 451 Ultimate strength, 8, 73, 114, 157, 405 SS, 109 475,526 1.4970 SS, 460,466 1.4981 SS, 460, 469 1.4988 SS, 137,460,463 Vacancies, 40, 65, 76, 93, 134, 145, 16Cr-13Ni-Cb,460 181, 188, 204, 237, 254, 261, 16Cr-16Ni-Cb,460 272,275,290,292,319,324 15Cr-15Ni-Ti-B,460 Vanadium, 75, 399, 401,403,529 Boron containing, 199 Vanadium alloys, 399 FV548, 509 V-Ti alloys, 403 Ti modified, 134 V-Cr alloys, 403 Strengthening, 6,81, 512 V-Cr-Ti alloys, 403 Stress rupture, 460 Voids, 85, 111, 122, 137, 155, 167, Structural steels 181, 187, 190, 214, 220, 228, A212-B, 17 243, 244, 247, 249, 262, 272, A302-B, 17, 41,79, 89,92,103 274, 289, 293, 294, 303, 317, A350-LF, 41 326, 360, 382, 400, 423, 460, A533-B,5,17 472 A543-l,17 Low alloys, 31 W Swelling, 78, 109, 111, 115, 122, 140, 149, 155, 199, 213, 217, 218, Welding, 7,79, 461,496 222, 228, 241, 247, 275, 308, 327,360,399 Yield strength, 8, 17, 43, 50, 67, 78, 114, 119, 157, 176, 181, 409, 427,451,475,501,505,530 Tantalum, 259, 263 Tenelon, 356 TensUe, 6, 52,64,114,116,149, 152, 170, 300, 351, 361, 383, 385, Zircaloy, 415 394,399,409,473,475,509 Texture, 431 Titanium, 63,138,400,403,448 Transition temperature increase, DTT, 6,18,31,39,61,81,92 Transmutations, 168, 183 Trapping, 66, 76, 79, 176, 239, 301, 311,413,530 Tubing, 133,381,415,461 Tungsten, 220,448 Twinning, 231,431 Copyright by ASTM Int'l (all rights reserved); Fri Jan 23:06:37 EST 2016 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized