焊后热处理对中锰钢电阻点焊接头组织及力学性能的影响  

Effect of Post-weld Heat Treatment on Microstructure and Mechanical Properties of Resistance Spot Welded Joint of Medium-manganese Steel

作　　者：潘华 雷鸣 PAN Hua;LEI Ming(Automobile Steel Research Institute,R&D Center,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China;State Key Laboratory of Development and Application Technology of Automotive Steels,Shanghai 201900,China)

机构地区：[1]宝山钢铁股份有限公司研究院汽车用钢研究所,上海201900 [2]汽车用钢开发与应用技术国家重点实验室,上海201900

出　　处：《上海金属》2019年第5期8-13,18,共7页Shanghai Metals

摘　　要：为提高冷轧中锰钢(0.13C-7Mn-0.22Si,质量分数,%)点焊接头的十字拉伸性能,对其进行了焊后热处理。采用光学显微镜(OM)、扫描电子显微镜(SEM)、拉伸试验机和显微硬度计,对比分析了热处理前后接头的显微组织、拉断载荷和显微硬度等。结果表明:焊态试样熔核区组织为马氏体,焊后热处理态试样熔核区组织为回火马氏体。焊态试样接头的拉断载荷为1.8 kN,为完全界面断裂,焊后热处理态的拉断载荷分别为5.1和4.9 kN,为部分界面断裂。焊后热处理可有效增加熔核的韧性,从而显著提高接头的性能。In order to increase the cross tensile properties of resistance spot welding joints in cold-rolled medium-manganese steel(0.13C-7Mn-0.22Si,mass fraction,%),the post-weld heat treatmens of the joints were carried out.The microstructure,fracture load and microhardness of the joints before and after the heat treatment were investigated and compared by optical microscope(OM),scanning electron microscope(SEM),tensile testing machine and microhardness tester.The results showed that the micorstructure in the nugget zone of as-welded specimen was martensite,and that of post-weld heat-treated specimen was tempered martensite.The fracture load of as-welded specimen was 1.8 kN,being full interfacial fracture(FIF);and the fracture loads of post-weld heat-treated specimens were 5.1 kN and 4.9 kN respectively,being partial interfacial fracture(PIF).Post-weld heat treatment could effectively increase the toughness of the nugget,thus significantly improving the performance of the joint.

关 键 词：中锰钢 电阻点焊 焊后热处理 断裂载荷 

分 类 号：TG1[金属学及工艺—金属学]