中低温热处理对SUS304不锈钢TIG焊接接头组织及力学性能的影响  

Effect of Heat Treatment on Microstructure and Properties of SUS304 Stainless Steel TIG Welded Joint

作　　者：鲍庆臣 渠怀志 史建强 宫明龙[2] BAO Qingchen;QU Huaizhi;SHI Jianqiang;GONG Minglong(CRRC Qingdao Sifang Rolling Stock Research Institute Co.,Ltd.,Qingdao 266000,China;School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]中车青岛四方车辆研究所有限公司,山东青岛266000 [2]东北大学,辽宁沈阳110819

出　　处：《电焊机》2022年第2期63-68,共6页Electric Welding Machine

基　　金：国家自然科学基金项目(51771044)。

摘　　要：轨道交通车辆在冲击振动试验后,部分设备SUS304不锈钢焊接件出现断裂失效现象。为了提升SUS304不锈钢焊后机械性能,采用金相显微镜、扫描电镜、硬度测试及拉伸试验等方法,研究了中低温热处理工艺对2 mm厚SUS304不锈钢板TIG焊接接头的组织及力学性能的影响。研究发现,经400℃热处理30 min及焊接后未处理态焊缝组织均由γ-奥氏体与δ-铁素体组成,δ-铁素体主要分布于富Cr区呈蠕虫状,热处理后δ-铁素体含量有一定程度的减少。焊接接头热处理后硬度值整体较未处理态低,焊后焊缝屈服强度为189.5 MPa,应变为64.5%,热处理后屈服强度为221 MPa,应变为72.7%,屈服强度提升了16.6%,达到母材的屈服强度。断口呈现出韧性断裂特征且无显著焊接缺陷,主要呈现出较深的韧窝,韧窝分布着第二相粒子,第二相粒子阻碍滑移造成应力集中而产生微坑,成为裂纹的主要发源地之一。After the impact and vibration test of rail transit vehicles, some equipment 304 stainless steel welded parts appeared fracture failure. In order to improve the mechanical properties of 304 stainless steel after welding, in this paper, by means of metallographic microscope, scanning electron microscope, hardness and tensile test, the effects of medium and low temperature heat treatment process on the microstructure and mechanical properties of 2 mm thick 304 stainless steel plate TIG welded joints were studied. It is found that the microstructure of the untreated weld is composed of γ-austenite and δ-ferrite after heat treatment at 400 ℃ for 30 min, and δ-ferrite mainly distributes in the Cr-rich zone and appears as a worm,and the content of δ-ferrite decreases to some extent after heat treatment. After heat treatment, the hardness of welded joints is lower than that of untreated ones. The yield strength of welded joints after welding is 189.5 MPa, and the strain is 64.5%.After heat treatment, the yield strength is 221 MPa, the strain is 72.7%, and the yield strength is increased by 16.6%, reaching the yield strength of base metal. The fracture surface shows ductile fracture characteristics and no significant welding defects, mainly showing deep dimples, and the dimples are distributed with second phase particles, which hinder the slip and cause stress concentration and produce micro-pits, which become one of the main craters of cracks.

关 键 词：SUS304 TIG焊 中低温热处理 微观组织 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]