C和W对低合金Cr-Mo钢焊缝金属组织和冲击韧性的影响  

Effect of C-and W-content on Microstructure and Toughness of Weld Metal for Low Alloy Cr-Mo Steel

作　　者：朱高文 吴栋[1] 陆善平[1] ZHU Gaowen;WU Dong;LU Shanping(Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所沈阳材料科学国家研究中心,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《材料研究学报》2021年第7期481-492,共12页Chinese Journal of Materials Research

基　　金：辽宁省科技重大专项(2020JH1/10100001);辽宁省自然科学基金(2019JH3/30100039)。

摘　　要：使用OM、SEM、EPMA、EBSD等手段并进行热膨胀和冲击等实验,研究了C和W元素对第四代钠冷快堆用低合金Cr-Mo钢钨极氩弧焊(TIG)熔敷金属微观组织和冲击韧性的影响。结果表明:多道次焊接热循环使多层多道焊缝金属的组织分布不均匀,分为表层焊缝组织和中间焊缝组织。表层焊缝组织,可分为熔化区(MZ)、粗晶区(CGHAZ)、细晶区(FGHAZ)、不完全相变区(ICHAZ)、临界再热粗晶区(ICCGHAZ)以及亚临界再热区(SCHAZ)。在中间焊缝金属中,有沿着原奥晶界分布的链状组织和等轴晶组织。等轴晶组织为回火贝氏体,韧性较好。链状组织中含有大量的二次硬化相M-A组元且存在应力集中,促进裂纹萌生并恶化焊缝金属韧性。提高C含量能促进表层焊缝金属中板条贝氏体和中间焊缝金属中链状组织的形成,从而恶化焊缝金属韧性;提高W含量能促进表层焊缝金属中板条贝氏体的形成、抑制中间焊缝金属中链状组织的形成,从而改善焊缝金属的韧性。The effect of C-and W-content on the microstructure and impact toughness of the weld metals for 2.25Cr1Mo steel weld via tungsten argon arc welding(TIG)technique was investigated by means of OM,SEM,EPMA,EBSD,thermal expansion-and impact-test.The results show that the microstructure of the multi-layer and multi-pass weld metal was heterogeneous,which can be divided into upper weld metal and intermediate weld metal.The upper weld metal can be divided into melting zone(MZ),coarse grain heat affected zone(CGHAZ),fine grain heat affected zone(FGHAZ),inter-critical heat affected zone(ICHAZ),inter-critically reheat coarse grain heat affected zone(ICCGHAZ)and sub-critical heat affected zone(SCHAZ).Intermediate weld metal composed of necklace-type microstructure which distribute along the prior austenite grain boundary and equiaxed crystal structure.The equiaxed crystal structure was tempered bainite with good toughness.Necklace-type microstructure composed of a large number of M-A constituents,which could easily cause stress concentration and promote crack initiation,whereas,deteriorate the toughness of weld metal.Increasing C content could promote the formation of lath bainite in upper weld metal and necklace-type microstructure in intermediate weld metal,which deteriorated the toughness of weld metal;However,increasing W content could promote the formation of lath bainite in upper weld metal and inhibit the formation of necklace-type microstructure in intermediate weld metal,which is beneficial to improving the toughness of weld metal.

关 键 词：金属材料 Cr-Mo钢焊缝金属 元素含量 链状组织 冲击韧性 

分 类 号：TG424[金属学及工艺—焊接]