Please wait a minute...
金属学报  2017, Vol. 53 Issue (1): 57-69    DOI: 10.11900/0412.1961.2016.00135
  本期目录 | 过刊浏览 |
国产核电安全端异种金属焊接件的微观结构及局部性能研究
明洪亮1,2,张志明1,王俭秋1(),韩恩厚1,苏明星3
1 中国科学院金属研究所核用材料与安全评价重点实验室, 辽宁省核电材料安全与评价技术重点实验室 沈阳 110016
2 中国科学院大学 北京 100049
3 上海核电装备焊接及检测工程技术研究中心 上海 201306
Microstructure and Local Properties of a Domestic Safe-End Dissimilar Metal Weld Joint by Using Hot-Wire GTAW
Hongliang MING1,2,Zhiming ZHANG1,Jianqiu WANG1(),En-Hou HAN1,Mingxing SU3
1 Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials, Key Laboratory of Nuclear Materials and Safety Assessment, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Shanghai Research Center for Weld and Detection Engineering Technique of Nuclear Equipment, Shanghai 201306, China
引用本文:

明洪亮,张志明,王俭秋,韩恩厚,苏明星. 国产核电安全端异种金属焊接件的微观结构及局部性能研究[J]. 金属学报, 2017, 53(1): 57-69.
Hongliang MING, Zhiming ZHANG, Jianqiu WANG, En-Hou HAN, Mingxing SU. Microstructure and Local Properties of a Domestic Safe-End Dissimilar Metal Weld Joint by Using Hot-Wire GTAW[J]. Acta Metall Sin, 2017, 53(1): 57-69.

全文: PDF(16657 KB)   HTML
摘要: 

利用OM、SEM、显微硬度仪、微小试样拉伸实验及慢应变速率拉伸实验对国产带热丝隔离层核电安全端焊接件不同部位的微观结构及局部的力学性能和应力腐蚀敏感性进行了研究。发现,在SA508/52Mb界面处的52Mb中具有大量的对应力腐蚀敏感的I型晶界及II型晶界,导致此界面具有最高的应力腐蚀敏感性;SA508热影响区存在明显的组织过渡;316LN热影响区中随着距熔合线距离的增加,重位点阵(CSL)晶界的数量分数逐渐增大,Σ3晶界与理想的Σ3晶界的偏差角减小,残余应变逐渐减小,残余应变的最高值出现在对接焊底焊位置处的316LN热影响区中,导致316LN的热影响区也具有较高的应力腐蚀敏感性。焊接件不同部位的力学性能存在较大的差异。对于硬度分布而言,显微硬度变化最剧烈的位置在SA508/52Mb界面附近,且此界面附近的52Mb具有最高的硬度,此界面附近的SA508脱C区具有最低的硬度。强度的变化趋势与硬度的变化趋势类似。一般强度高的地方断裂应变低。焊接件不同位置的性能差异主要取决于不同部位的微观结构(包含组织、成分等)差异。

关键词 异种金属焊接微观结构局部力学性能应力腐蚀敏感性残余应变    
Abstract

Dissimilar metal weld joints (DMWJ) widely exist in the nuclear power plants to join the different parts which are made of different structural materials. Among these DMWJs, safe-end DMWJ has attracted much attention of researchers and operating enterprises, as premature failures, mainly stress corrosion cracking failures, have occurred in these kinds of joints. However, DMWJ with 52M as filler metal in the nuclear power plants has no in-service experience. To ensure the structural integrity of the weld joint and the safe operation of the future plants, the microstructure and local properties of a domestic safe-end DMWJ by using hot-wire gas tungsten arc welding (GTAW) technology was studied in detail by OM, SEM, micro-hardness testing, local mechanical tensile testing and slow strain rate tests. The tensile tests were performed at room temperature with the tensile speed of 5 μm/s while the slow strain rate tests were conducted in simulated primary water containing 1500 mg/L B as H3BO3 and 2.3 mg/L Li as LiOH with 2 mg/L dissolved oxygen at 325 ℃. A large amount of type I boundaries and type II boundaries which are susceptible to stress corrosion cracking (SCC) exist in 52Mb near the SA508/52Mb interface and result in the highest SCC susceptibility of this interface. Microstructure transition was found in the SA508 heat affected zone (HAZ). In 316LN HAZ, increasing the distance from the fusion boundary, the number fraction of CSL boundaries increase while the residual strain decreases, resulting in the second-highest SCC susceptibility of 316LN HAZ. In 52M, residual strain distributes randomly but not uniformly, the residual strain is prone to accumulate at the grain boundaries. Dramatic changes of mechanical properties are observed across the joint, especially at the SA508/52M interface. The differences of the local microstructure and chemical composition lead to the differences of the local properties of the weld joint.

Key wordsdissimilar metal    weld joint,    microstructure,    local mechanical property,    stress corrosion cracking susceptibility,    residual strain
收稿日期: 2016-04-13     
基金资助:资助项目 国家自然科学基金项目No.51301183,上海市科委项目No.14DZ2250300和中国科学院前沿科学重点研究项目No.QYZDY-SSW-JSC012
Material C Si Mn Cr Ni S P Fe N Mo
316LN 0.014 0.624 1.576 17.34 10.84 <0.001 0.026 Bal. 0.116 2.210
SA508 0.170 0.210 1.360 0.16 0.80 0.001 0.006 Bal. - 0.490
52Mb 0.019 0.110 0.810 29.77 59.20 <0.0005 0.003 8.73 0.006 0.008
52Mw 0.023 0.110 0.900 29.76 58.80 <0.0005 0.003 8.74 0.006 0.100
Material Co Cu Al Ti Cb(Nb)+Ta V B Zr Other
316LN <0.050 - - - - - - - -
SA508 - 0.04 - - - 0.005 - - -
52Mb 0.010 0.03 0.11 0.17 0.89 - 0.0007 0.010 <0.500
52Mw 0.006 0.02 0.11 0.19 0.89 - 0.0005 0.003 <0.494
表1  焊接件不同部位主要化学成分
图1  焊接实物图和焊接件截面示意图及取样示意图
图2  小尺寸拉伸试样尺寸示意图
图3  慢应变速率拉伸实验试样尺寸示意图
图4  小尺寸拉伸试样在焊接件中的位置示意图
图5  SA508母材、316LN母材、 52Mb和 52Mw 的OM像
图6  SA508/52Mb界面和52Mw/316LN界面的OM像
图7  SA508低合金钢热影响区的OM像
图8  316LN热影响区的OM像
图9  无马氏体区的SA508/52Mb界面形貌及主要金属元素分布
图10  带有马氏体区的SA508/52Mb界面形貌及主要金属元素分布
图11  52Mw/316LN界面形貌及主要金属元素分布
图12  H1、H4及H6试样EBSD分析
图13  H4试样SA508/52Mb界面的图像质量(image quality, IQ)图、IPF、KAM图及相分布图
图14  沿图1b中L1线的显微硬度分布及界面处显微硬度压痕
图15  沿图1b中L2线的显微硬度分布及界面处显微硬度压痕
图16  沿图1b中L3线的显微硬度分布及界面处显微硬度压痕
图17  SA508/52Mb界面的SEM像及C元素分布
图18  焊接件不同部位室温下屈服强度、抗拉强度及断裂应变
图19  焊接件不同部位在模拟核电高温高压水环境中慢应变速率拉伸实验结果
图20  H1试样中316LN侧距熔合线不同距离位置处Σ3晶界与理想的Σ3晶界偏差角分布图
[1] Li G F, Yang W.Cracking of dissimilar metal welds in nuclear power plants and methods to evaluate its susceptibility to stress corrosion cracking[J]. Nucl. Saf., 2003, (2): 37
[1] (李光福, 杨武. 核电站异材焊接件的破裂问题与应力腐蚀评价方法[J]. 核安全, 2003, (2): 37)
[2] Wang H T, Wang G Z, Xuan F Z, et al.Local mechanical properties of a dissimilar metal welded joint in nuclear powersystems[J]. Mater. Sci. Eng., 2013, A568: 108
[3] Lu Z P, Shoji T, Yamazaki S, et al.Characterization of microstructure, local deformation and microchemistry in Alloy 600 heat-affected zone and stress corrosion cracking in high temperature water[J]. Corros. Sci., 2012, 58: 211
[4] Hou J, Peng Q J, Takeda Y, et al.Microstructure and stress corrosion cracking of the fusion boundary region in an Alloy 182-A533B low alloy steel dissimilar weld joint[J]. Corros. Sci., 2010, 52: 3949
[5] Hou J, Shoji T, Lu Z P, et al.Residual strain measurement and grain boundary characterization in the heat-affected zone of a weld joint between Alloy 690TT and Alloy 52[J]. J. Nucl. Mater., 2010, 397: 109
[6] Ming H L, Zhang Z M, Wang J Q, et al.Microstructural characterization of an SA508-309L/308L-316L domestic dissimilar metal welded safe-end joint[J]. Mater. Charact., 2014, 97: 101
[7] Wang S Y, Ding J, Ming H L, et al.Characterization of low alloy ferritic steel-Ni base alloy dissimilar metal weld interface by SPM techniques, SEM/EDS, TEM/EDS and SVET[J]. Mater. Charact., 2015, 100: 50
[8] Hou J, Peng Q J, Takeda Y, et al.Microstructure and mechanical property of the fusion boundary region in an alloy 182-low alloy steel dissimilar weld joint[J]. J. Mater. Sci., 2010, 45: 5332
[9] Chung W C, Huang J Y, Tsay L W, et al.Microstructure and stress corrosion cracking behavior of the weld metal in alloy 52-A508 dissimilar welds[J]. Mater. Trans., 2011, 52: 12
[10] Hou J, Peng Q J, Shoji T, et al.Study of microstructure and stress corrosion cracking behavior in welding transition zone of Ni-based alloys[J]. Acta Metall. Sin., 2010, 46: 1258
[10] (侯娟, 彭群家, 庄子哲雄等. 镍基合金焊接过渡区微观结构及应力腐蚀行为研究[J]. 金属学报, 2010, 46: 1258)
[11] Ding J, Zhang Z M, Wang J Q, et al.Micro-characterization of dissimilar metal weld joint for connecting pipe-nozzle to safe-end in generation III nuclear power plant[J]. Acta Metall. Sin., 2015, 51: 425
[11] (丁杰, 张志明, 王俭秋等. 三代核电接管安全端异种金属焊接接头的显微表征[J]. 金属学报, 2015, 51: 425)
[12] Ming H L, Zhang Z M, Xiu P Y, et al.Microstructure, Residual strain and stress corrosion cracking behavior in 316L heat-affected zone[J]. Acta Metall. Sin.(Engl. Lett.), 2016, 29: 848
[13] Li G F, Congleton J.Stress corrosion cracking of a low alloy steel to stainless steel transition weld in PWR primary waters at 292 ℃[J]. Corros. Sci., 2000, 42: 1005
[14] Li G F, Li G J, Fang K W, et al.Stress corrosion cracking behavior of dissimilar metal weld A508/52M/316L in high temperature water environment[J]. Acta Metall. Sin., 2011, 47: 797
[14] (李光福, 李冠军, 方可伟等. 异材焊接件A508/52M/316L在高温水环境中的应力腐蚀破裂[J]. 金属学报, 2011, 47: 797)
[15] Deng D, Murakawa H.Numerical simulation of temperature field and residual stress in multi-pass welds in stainless steel pipe and comparison with experimental measurements[J]. Comput. Mater. Sci., 2006, 37: 269
[16] Lim Y S, Kim H P, Cho H D, et al.Microscopic examination of an alloy 600/182 weld[J]. Mater. Charact., 2009, 60: 1496
[17] Ming H L, Zhu R L, Zhang Z M, et al.Microstructure, local mechanical properties and stress corrosion cracking susceptibility of an SA508-52M-316LN safe-end dissimilar metal weld joint by GTAW[J]. Mater. Sci. Eng., 2016, A669: 279
[18] Nelson T W, Lippold J C, Mills M J.Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar metal welds-Part 2: on-cooling transformations[J]. Weld. J., 2000, 79: 267s
[19] Wu Y, Patchett B M.Formation of crack-susceptible structures of weld overlay of corrosion resistant alloys[J]. Mater. Perform.: Sulphur Energy, 1992, 32: 83
[20] Yoo S C, Choi K J, Bahn C B, et al.Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints[J]. J. Nucl. Mater., 2015, 459: 5
[21] Kou S.Welding Metallurgy[M]. 2nd Ed., Hoboken, New Jersey: John Wiley & Sons Inc., 2003: 170
[22] Srinivasan P B, Muthupandi V, Dietzel W, et al.An assessment of impact strength and corrosion behaviour of shielded metal arc welded dissimilar weldments between UNS 31803 and IS 2062 steels[J]. Mater. Des., 2006, 27: 182
[23] Qiao D X, Zhang W, Pan T Y, et al.Evaluation of residual plastic strain distribution in dissimilar metal weld by hardness mapping[J]. Sci. Technol. Weld. Joi., 2013, 18: 624
[24] Bhaduri A K, Venkadesan S, Rodriguez P, et al.Transition metal joints for steam generators-an overview [J]. Int. J. Press. Vessels Pip., 1994, 58: 251
[25] Kuniya J, Masaoka I, Sasaki R.Effect of cold work on the stress corrosion cracking of nonsensitized AISI 304 stainless steel in high-temperature oxygenated water[J]. Corrosion, 1988, 44: 21
[26] Fang H Y.Welding Structural [M]. Beijing: Mechanical Industry Press, 2008: 56
[26] (方洪渊. 焊接结构学 [M]. 北京: 机械工业出版社, 2008: 56)
[27] Zhang L T, Wang J Q.Stress corrosion crack propagation behavior of domestic forged nuclear grade 316L stainless steel in high temperature and high pressure water[J]. Acta Metall. Sin., 2013, 49: 911
[27] (张利涛, 王俭秋. 国产锻造态核级管材316L不锈钢在高温高压水中的应力腐蚀裂纹扩展行为[J]. 金属学报, 2013, 49: 911)
[28] Andresen P L.Suzhou international seminar on welding and non-destructive examination in nuclear power plants, Suzhou, China, 2009 (CD-ROM)
[29] Zhang L T, Wang J Q.Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment[J]. J. Nucl. Mater., 2014, 446: 15
[30] Hu C L, Xia S, Li H, et al.Effect of grain boundary network on the intergranular stress corrosion cracking of 304 stainless steel[J]. Acta Metall. Sin., 2011, 47: 939
[30] (胡长亮, 夏爽, 李慧等. 晶界网络特征对304不锈钢晶间应力腐蚀开裂的影响[J]. 金属学报, 2011, 47: 939)
[31] Gertsman V Y, Bruemmer S M.Study of grain boundary character along intergranular stress corrosion crack paths in austenitic alloys[J]. Acta Mater., 2001, 49: 1589
[32] Tan L, Allen T R, Busby J T.Grain boundary engineering for structure materials of nuclear reactors[J]. J. Nucl. Mater., 2013, 441: 661
[33] West E A, Was G S.IGSCC of grain boundary engineered 316L and 690 in supercritical water[J]. J. Nucl. Mater., 2009, 392: 264
[1] 张德印, 郝旭, 贾宝瑞, 吴昊阳, 秦明礼, 曲选辉. Y2O3 含量对燃烧合成Fe-Y2O3 纳米复合粉末性能的影响[J]. 金属学报, 2023, 59(6): 757-766.
[2] 刘满平, 薛周磊, 彭振, 陈昱林, 丁立鹏, 贾志宏. 后时效对超细晶6061铝合金微观结构与力学性能的影响[J]. 金属学报, 2023, 59(5): 657-667.
[3] 杨超, 卢海洲, 马宏伟, 蔡潍锶. 选区激光熔化NiTi形状记忆合金研究进展[J]. 金属学报, 2023, 59(1): 55-74.
[4] 解磊鹏, 孙文瑶, 陈明辉, 王金龙, 王福会. 制备工艺对FGH4097高温合金微观组织与性能的影响[J]. 金属学报, 2022, 58(8): 992-1002.
[5] 吴进, 杨杰, 陈浩峰. 纳入残余应力时不同拘束下DMWJ的断裂行为[J]. 金属学报, 2022, 58(7): 956-964.
[6] 李金富, 李伟. 铝基非晶合金的结构与非晶形成能力[J]. 金属学报, 2022, 58(4): 457-472.
[7] 张显程, 张勇, 李晓, 王梓萌, 贺琛贇, 陆体文, 王晓坤, 贾云飞, 涂善东. 异构金属材料的设计与制造[J]. 金属学报, 2022, 58(11): 1399-1415.
[8] 马敏静, 屈银虎, 王哲, 王军, 杜丹. Ag-CuO触点材料侵蚀过程的演化动力学及力学性能[J]. 金属学报, 2022, 58(10): 1305-1315.
[9] 王洪伟, 何竹风, 贾楠. 非均匀组织FeMnCoCr高熵合金的微观结构和力学性能[J]. 金属学报, 2021, 57(5): 632-640.
[10] 潘杰, 段峰辉. 非晶合金的回春行为[J]. 金属学报, 2021, 57(4): 439-452.
[11] 李宁, 黄信. 块体非晶合金的3D打印成形研究进展[J]. 金属学报, 2021, 57(4): 529-541.
[12] 杨勇, 赫全锋. 高熵合金中的晶格畸变[J]. 金属学报, 2021, 57(4): 385-392.
[13] 周丽, 李明, 王全兆, 崔超, 肖伯律, 马宗义. 31%B4Cp/6061Al复合材料的热变形及加工图的研究[J]. 金属学报, 2020, 56(8): 1155-1164.
[14] 杨杰, 王雷. 核电站DMWJ中材料拘束的影响与优化[J]. 金属学报, 2020, 56(6): 840-848.
[15] 刘天, 罗锐, 程晓农, 郑琦, 陈乐利, 王茜. 形成Al2O3表层的奥氏体不锈钢加速蠕变实验研究[J]. 金属学报, 2020, 56(11): 1452-1462.