Please wait a minute...
金属学报  2019, Vol. 55 Issue (5): 555-565    DOI: 10.11900/0412.1961.2018.00365
  本期目录 | 过刊浏览 |
退火对热老化308L不锈钢焊材显微结构的影响
林晓冬1,2,彭群家1,3(),韩恩厚1,柯伟1
1. 中国科学院金属研究所核用材料与安全性评价重点实验室 沈阳 110016
2. 中国科学技术大学材料科学与工程学院 沈阳 110016
3. 苏州热工研究院有限公司 苏州 215004
Effect of Annealing on Microstructure of Thermally Aged 308L Stainless Steel Weld Metal
Xiaodong LIN1,2,Qunjia PENG1,3(),En-Hou HAN1,Wei KE1
1. Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China
3. Suzhou Nuclear Power Research Institute, Suzhou 215004, China
引用本文:

林晓冬,彭群家,韩恩厚,柯伟. 退火对热老化308L不锈钢焊材显微结构的影响[J]. 金属学报, 2019, 55(5): 555-565.
Xiaodong LIN, Qunjia PENG, En-Hou HAN, Wei KE. Effect of Annealing on Microstructure of Thermally Aged 308L Stainless Steel Weld Metal[J]. Acta Metall Sin, 2019, 55(5): 555-565.

全文: PDF(22244 KB)   HTML
摘要: 

对410 ℃下热老化7000 h的308L不锈钢焊材进行了550 ℃、1 h的退火处理,利用TEM和三维原子探针研究了退火对热老化焊材显微结构的影响,并与未热老化试样进行比较,评价退火回复效果。结果表明,退火后奥氏体无明显变化,而δ铁素体内由热老化导致的调幅分解完全消失,且G相显著减少。此外,热老化导致Ni、Mn、C在δ铁素体/奥氏体相界处发生偏聚,而对相界处Cr、Si、P元素的含量无明显影响。退火后相界处所有元素均无偏聚,但会导致Ni、Mn在靠近相界的奥氏体一侧发生富集。退火后308L不锈钢焊材的显微结构接近于未热老化状态,表明退火回复效果显著。

关键词 不锈钢焊材热老化退火调幅分解G相析出相界偏聚    
Abstract

Austenitic stainless steel weld metal has been widely used as nozzle/safe-end joint and inner surface cladding of reactor pressure vessel, due to its good mechanical property and corrosion resistance. However, long-term thermal ageing at the service temperature (280~330 ℃) could induce hardening and embrittlement of the weld metal. To recover the thermal ageing embrittlement, the annealing treatment has been proposed since the annealing could affect the ageing-induced microstructural changes such as spinodal decomposition and G-phase precipitation in ferrite. However, there is still an incomplete understanding as well as a lack of nanoscale investigation about the annealing effect on the microstructural change of the weld metal. In this work, 308L stainless steel weld metal was thermally aged at 410 ℃ for 7000 h, followed by an annealing treatment at 550 ℃ for 1 h. Since the weld metal has a dual-phase structure of austenite and δ-ferrite, the phase transformation of austenite and δ-ferrite as well as the element segregation at the δ-ferrite/austenite phase boundary were investigated by TEM and atom probe tomography. The results revealed that austenite was unaffected by annealing while the ageing-induced spinodal decomposition of δ-ferrite was completely recovered. In addition, the number density of G phase in δ-ferrite was significantly reduced following annealing. This indicates that austenite has a higher stability compared with δ-ferrite. As for the δ-ferrite/austenite phase boundary, thermal ageing induced the segregation of Ni, Mn and C at the phase boundary, while the contents of Cr, Si and P remained almost unchanged. Following the annealing treatment, the segregation of all elements was eliminated. Further, only a small quantity of Ni and Mn was enriched in austenite near the phase boundary. The results suggested that the microstructure of the annealed specimen was similar to that of the unaged specimen, indicating a good recovery of the microstructure by annealing.

Key wordsstainless steel weld metal    thermal ageing    annealing    spinodal decomposition    G phase precipitation    phase boundary segregation
收稿日期: 2018-08-11     
ZTFLH:  TG139.4  
基金资助:国家自然科学基金项目(51571204)
作者简介: 林晓冬,男,1991年生,博士
图1  308L不锈钢焊材的显微组织和δ铁素体/奥氏体相界区域的HRTEM像
图2  原始态、7000 h热老化和退火试样中奥氏体相的明场像和内部元素分布
图3  原始态、7000 h热老化、退火试样中δ铁素体相的TEM像和Cr元素分布
图4  δ铁素体中调幅分解区域内部Fe、Cr一维成分分布与浓度频率分布
图5  G相的暗场像、电子衍射花样和HRTEM像
图6  原始态、7000 h热老化、退火试样中δ铁素体相内Ni、Si、Mn、P、Cu元素分布
图7  横跨G相的一维成分分布
图8  原始态、7000 h热老化、退火试样中δ铁素体/奥氏体相界区域的元素分布及横跨相界的一维浓度分布
图9  未热老化、7000 h热老化和退火试样调幅分解区域内Fe、Cr的参数V
图10  7000 h热老化和退火试样中靠近相界处的δ铁素体一侧的贫Ni区
[1] MaC, HanE H, PengQ J, et al. Effect of polishing process on corrosion behavior of 308L stainless steel in high temperature water[J]. Appl. Surf. Sci., 2018, 442: 423
[2] DeLongW T. Ferrite in austenitic stainless steel weld metal[J]. Weld. J., 1974, 53: 273s
[3] RaoK P, KumarS P. Corrosion behavior of austenitic weld and clad metals in accelerated boiling acid tests simulating passive conditions[J]. Corrosion, 1986, 42: 1
[4] DongL J, HanE H, PengQ J, et al. Environmentally assisted crack growth in 308L stainless steel weld metal in simulated primary water[J]. Corros. Sci., 2017, 117: 1
[5] LeeJ S, KimI S, KasadaR, et al. Microstructural characteristics and embrittlement phenomena in neutron irradiated 309L stainless steel RPV clad[J]. J. Nucl. Mater., 2004, 326: 38
[6] ChungH M, LeaxT R. Embrittlement of laboratory and reactor aged CF3,CF8, and CF8M duplex stainless steels[J]. Mater. Sci. Technol., 1990, 6: 249
[7] LiS L, WangY L, WangX T, et al. G-phase precipitation in duplex stainless steels after long-term thermal aging: A high-resolution transmission electron microscopy study[J]. J. Nucl. Mater., 2014, 452: 382
[8] TakeuchiT, KamedaJ, NagaiY, et al. Study on microstructural changes in thermally-aged stainless steel weld-overlay cladding of nuclear reactor pressure vessels by atom probe tomography[J]. J. Nucl. Mater., 2011, 415: 198
[9] AlexanderK B, MillerM K, AlexanderD J, et al. Microscopical evaluation of low temperature aging of type 308 stainless steel weldments[J]. Mater. Sci. Technol., 1990, 6: 314
[10] DanoixF, AugerP, BlavetteD. Hardening of aged duplex stainless steels by spinodal decomposition[J]. Microsc. Microanal., 2004, 10: 349
[11] CaoX Y, ZhuP, DingX F, et al. An investigation on microstructure and mechanical property of thermally aged stainless steel weld overlay cladding[J]. J. Nucl. Mater., 2017, 486: 172
[12] TakeuchiT, KakuboY, MatsukawaY, et al. Effects of thermal aging on microstructure and hardness of stainless steel weld-overlay claddings of nuclear reactor pressure vessels[J]. J. Nucl. Mater., 2014, 452: 235
[13] JangH, HongS H, JangC, et al. The effects of reversion heat treatment on the recovery of thermal aging embrittlement of CF8M cast stainless steels[J]. Mater. Des., 2014, 56: 517
[14] LiS L, ZhangH L, WangY L, et al. Annealing induced recovery of long-term thermal aging embrittlement in a duplex stainless steel[J]. Mater. Sci. Eng., 2013, A564: 85
[15] MateoA, PalominoJ L, SalanN, et al. Mechanical evaluation of a reversion heat treatment for a duplex stainless steel thermally embrittled[A]. Proceedings of the 11th Biennial European Conference on Fracture[C]. Warley: Engineering Materials Advisory Services Ltd., 1996: 779
[16] BrooksJ A, ThompsonA W. Microstructural development and solidification cracking susceptibility of austenitic stainless steel welds[J]. Int. Mater. Rev., 1991, 36: 16
[17] LongC J, De LongW T. The ferrite content of austenitic stainless steel weld metal[J]. Weld. J., 1973, 52: 281S
[18] NateshM, ShamanthV, RavishankarK S. Effect of reversion heat treatment on the mechanical properties of thermally embrittled UNS S32760 duplex stainless steel[J]. Mater. Sci. Forum, 2015, 830-831: 127
[19] ShamanthV, RavishankarK S. Dissolution of alpha-prime precipitates in thermally embrittled S2205-duplex steels during reversion-heat treatment[J]. Results Phys., 2015, 5: 297
[20] ChungH M. Aging and life prediction of cast duplex stainless steel components[J]. Int. J. Pres, Ves. Pip., 1992, 50: 179
[21] VitekJ M, DavidS A, AlexanderD J, et al. Low temperature aging behavior of type 308 stainless steel weld metal[J]. Acta Metall. Mater., 1991, 39: 503
[22] TakeuchiT, KamedaJ, NagaiY, et al. Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels[J]. J. Nucl. Mater., 2012, 425: 60
[23] LachT G, ByunT S, LeonardK J, Mechanical property degradation and microstructural evolution of cast austenitic stainless steels under short-term thermal aging [J]. J. Nucl. Mater., 2017, 497: 139
[24] ZhangB, XueF, LiS L, et al. Non-uniform phase separation in ferrite of a duplex stainless steel[J]. Acta Mater., 2017, 140: 388
[25] BruemmerS M. Grain boundary composition and effects on environmental degradation[A]. 9th International Conference on Intergranular and Interphase Boundaries in Materials[C]. Zurich-Uetikon: Transtec Publications Ltd., 1999: 75
[26] JiaoZ J, WasG S. Novel features of radiation-induced segregation and radiation-induced precipitation in austenitic stainless steels[J]. Acta Mater., 2011, 59: 1220
[27] HallR N. Variation of the distribution coefficient and solid solubility with temperature[J]. J. Phys. Chem. Solids, 1957, 3: 63
[28] AugerP, DanoixF, MenandA, et al. Atom probe and transmission electron microscopy study of aging of cast duplex stainless steels[J]. Mater. Sci. Technol., 1990, 6: 301
[29] StrangwoodM, DruceS G. Aging effects in welded cast CF3 stainless steel[J]. Mater. Sci. Technol., 1990, 6: 237
[30] PumphreyP H, AkhurstK N. Aging kinetics of CF3 cast stainless steel in temperature range 300-400 ℃[J]. Mater. Sci. Technol., 2013, 6: 211
[31] YamadaT, OkanoS, KuwanoH. Mechanical property and microstructural change by thermal aging of SCS14A cast duplex stainless steel[J]. J. Nucl. Mater., 2006, 350: 47
[32] KawaguchiS, SakamotoN, TakanoG, et al. Microstructural changes and fracture behavior of CF8M duplex stainless steels after long-term aging[J]. Nucl. Eng. Des., 1997, 174: 273
[33] XuX, WestraadtJ E, OdqvistJ, et al. Effect of heat treatment above the miscibility gap on nanostructure formation due to spinodal decomposition in Fe-52.85at.%Cr[J]. Acta Mater., 2018, 145: 347
[34] DengP, PengQ J, HanE-H, et al. Study of irradiation damage in domestically fabricated nuclear grade stainless steel[J].Acta Metall. Sin., 2017, 53: 1588
[34] (邓 平, 彭群家, 韩恩厚等. 国产核用不锈钢辐照损伤研究 [J]. 金属学报, 2017, 53: 1588)
[35] ThompsonK, LawrenceD, LarsonD J, et al. In situ site-specific specimen preparation for atom probe tomography[J]. Ultramicroscopy, 2007, 107: 131
[36] MillerM K, KenikE A. Atom probe tomography: A technique for nanoscale characterization[J]. Microsc. Microanal., 2004, 10: 336
[37] LiuW Q, LiuQ D, GuJ F. Development and application of atom probe tomography[J].Acta Metall. Sin., 2013, 49: 1025
[37] (刘文庆, 刘庆冬, 顾剑锋. 原子探针层析技术(APT)最新进展及应用 [J]. 金属学报, 2013, 49: 1025)
[38] ChandraK, KainV, RajaV S, et al. Low temperature thermal ageing embrittlement of austenitic stainless steel welds and its electrochemical assessment[J]. Corros. Sci., 2012, 54: 278
[39] LiS L, WangY L, LiS X, et al. Microstructures and mechanical properties of cast austenite stainless steels after long-term thermal aging at low temperature[J]. Mater. Des., 2013, 50: 886
[40] DanoixF, AugerP. Atom probe studies of the Fe-Cr system and stainless steels aged at intermediate temperature: A review[J]. Mater. Charact., 2000, 44: 177
[41] LiS L, WangY L, ZhangH L, et al. Microstructure evolution and impact fracture behaviors of Z3CN20-09M stainless steels after long-term thermal aging[J]. J. Nucl. Mater., 2013, 433: 41
[42] ChandraD, SchwartzL H. M?ssbauer effect study of the 475 ℃ decomposition of Fe-Cr[J]. Metall. Trans., 1971, 2: 511
[43] MatsukawaY, TakeuchiT, KakuboY, et al. The two-step nucleation of G-phase in ferrite[J]. Acta Mater., 2016, 116: 104
[44] PareigeC, EmoJ, SailletS, et al. Kinetics of G-phase precipitation and spinodal decomposition in very long aged ferrite of a Mo-free duplex stainless steel[J]. J. Nucl. Mater., 2015, 465: 383
[45] DanoixF, AugerP, BlavetteD. An atom-probe investigation of some correlated phase transformations in Cr, Ni, Mo containing supersaturated ferrites[J]. Surf. Sci., 1992, 266: 364
[46] MateoA, LlanesL, AngladaM, et al. Characterization of the intermetallic G-phase in an AISI 329 duplex stainless steel[J]. J. Mater. Sci., 1997, 32: 4533
[47] HamaokaT, KonnoT J, SawabeT, et al. Effects of molybdenum on precipitation behaviours in aged cast stainless steels[J]. Philos. Mag., 2016, 96: 2518
[48] BabuS S, DavidS A, VitekJ M, et al. Atom probe field ion microscopy of type 308 CRE stainless steel welds[J]. Appl. Surf. Sci., 1995, 87-88: 207
[49] LiH, XiaS, LiuW Q, et al. Atomic scale study of grain boundary segregation before carbide nucleation in Ni-Cr-Fe alloys[J]. J. Nucl. Mater., 2013, 439: 57
[50] LiH, XiaS, ZhouB X, et al. C-Cr segregation at grain boundary before the carbide nucleation in alloy 690[J]. Mater. Charact., 2012, 66: 68
[51] JiaoZ J, HesterbergJ, WasG S. Effect of post-irradiation annealing on the irradiated microstructure of neutron-irradiated 304L stainless steel[J]. J. Nucl. Mater., 2018, 500: 220
[52] Bar'yakhtarV G, TimoshevskiiA N, SoolshenkoV K, et al. Influence of substitutional (Cr, Mn, Ni) and interstitial (C, N, O) impurities on the electronic structure and magnetic properties of α-Fe based alloys[J]. J. Magn. Magn. Mater., 1995, 140-144: 115
[53] BlanterM S, MagalasL B. Carbon-substitutional interaction in austenite[J]. Scr. Mater., 2000, 43: 435
[54] ChenQ, JeppssonJ, ?grenJ. Analytical treatment of diffusion during precipitate growth in multicomponent systems[J]. Acta Mater., 2008, 56: 1890
[1] 陈学双, 黄兴民, 刘俊杰, 吕超, 张娟. 一种含富锰偏析带的热轧临界退火中锰钢的组织调控及强化机制[J]. 金属学报, 2023, 59(11): 1448-1456.
[2] 于少霞, 王麒, 邓想涛, 王昭东. GH3600镍基高温合金极薄带的制备及尺寸效应[J]. 金属学报, 2023, 59(10): 1365-1375.
[3] 金鑫焱, 储双杰, 彭俊, 胡广魁. 露点对连续退火0.2%C-1.5%Si-2.5%Mn高强钢选择性氧化及脱碳的影响[J]. 金属学报, 2023, 59(10): 1324-1334.
[4] 杨平, 王金华, 马丹丹, 庞树芳, 崔凤娥. 成分对真空脱锰法相变控制高硅电工钢{100}织构的影响[J]. 金属学报, 2022, 58(10): 1261-1270.
[5] 项兆龙, 张林, XIN Yan, 安佰灵, NIU Rongmei, LU Jun, MARDANI Masoud, HAN Ke, 王恩刚. Cr含量对FeCrCoSi永磁合金调幅分解组织及其性能的影响[J]. 金属学报, 2022, 58(1): 103-113.
[6] 王玉, 胡斌, 刘星毅, 张浩, 张灏云, 官志强, 罗海文. 退火温度对含Nb高锰钢力学和阻尼性能的影响[J]. 金属学报, 2021, 57(12): 1588-1594.
[7] 李索, 陈维奇, 胡龙, 邓德安. 加工硬化和退火软化效应对316不锈钢厚壁管-管对接接头残余应力计算精度的影响[J]. 金属学报, 2021, 57(12): 1653-1666.
[8] 姚小飞, 魏敬鹏, 吕煜坤, 李田野. (CoCrFeMnNi)97.02Mo2.98高熵合金σ相析出演变及力学性能[J]. 金属学报, 2020, 56(5): 769-775.
[9] 曹育菡,王理林,吴庆峰,何峰,张忠明,王志军. CoCrFeNiMo0.2高熵合金的不完全再结晶组织与力学性能[J]. 金属学报, 2020, 56(3): 333-339.
[10] 李文涛,王振玉,张栋,潘建国,柯培玲,汪爱英. 电弧复合磁控溅射结合热退火制备Ti2AlC涂层[J]. 金属学报, 2019, 55(5): 647-656.
[11] 刘后龙,马明玉,刘玲玲,魏亮亮,陈礼清. 热轧板退火工艺对19Cr2Mo1W铁素体不锈钢织构与成形性能的影响[J]. 金属学报, 2019, 55(5): 566-574.
[12] 邵成伟, 惠卫军, 张永健, 赵晓丽, 翁宇庆. 一种新型高强度高塑性冷轧中锰钢的组织和力学性能[J]. 金属学报, 2019, 55(2): 191-201.
[13] 邵毅, 李彦默, 刘晨曦, 严泽生, 刘永长. 低碳铁素体不锈钢高频直缝电阻焊管退火工艺优化[J]. 金属学报, 2019, 55(11): 1367-1378.
[14] 赵晓丽, 张永健, 邵成伟, 惠卫军, 董瀚. 两相区退火处理冷轧0.1C-5Mn中锰钢的氢脆敏感性[J]. 金属学报, 2018, 54(7): 1031-1041.
[15] 耿林, 吴昊, 崔喜平, 范国华. 基于箔材反应退火合成的TiAl基复合材料板材研究进展[J]. 金属学报, 2018, 54(11): 1625-1636.