摘要
通过光学显微镜(OM)和扫描电子显微镜(SEM)对不同焊接工艺参数的中锰钢电阻点焊组织进行了表征,并分析了熔核区柱状晶的形成机制。结果显示,当保载时间为100ms时,金属收缩后形成的孔洞未能得到液态金属足够的补充,从而形成凝固缩松。当电阻点焊的保载时间延长至400 ms之后,熔核凝固引起的收缩量得到更多补偿,因此熔核区的凝固缩松基本消除,达到了改善组织的目的。此外,在电阻点焊后冷却的过程中,熔核内的液态金属沿与散热方向相反的方向长大,从而在熔核区形成了柱状晶组织。
The microstructure of resistance spot welded medium-manganese steel with different welding parameters was characterized by optical microscope(OM)and scanning electron microscope(SEM),and the formation mechanism of columnar crystals in nugget zone was analyzed.The results showed that when the loading time was 100 ms,the pores formed after the shrinkage of the metal can not be adequately supplied by the liquid metal,resulting in the formation of the solidification shrinkage.When the loading time of the resistance spot welding was increased to 400 ms,the shrinkage caused by the solidification of the nugget was compensated more adequately,accordingly,the shrinkage porosity in the nugget zone was basically eliminated,and the microstructure was therefore improved.Furthermore,in the cooling process after resistance spot welding,the liquid metal in the nugget grew up along the direction opposite to the heat transfer,and thus forming the columnar crystals in the nugget zone.
作者
孙臣玉
潘华
雷鸣
丁凯
王远方
高玉来
Sun Chenyu;Pan Hua;Lei Ming;Ding Kai;Wang Yuanfang;Gao Yulai(State Key Laboratory of Advanced Special Steel&Shanghai Key Laboratory of Advanced Ferrometallurgy &School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China;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)
出处
《上海金属》
CAS
北大核心
2018年第5期1-5,共5页
Shanghai Metals
基金
国家自然科学基金(No.U1760102)
汽车用钢开发与应用技术国家重点实验室开放课题
关键词
中锰钢
电阻点焊
显微组织
保载时间
medium-manganese steel
resistance spot welding
microstructure
loading time
