不等厚高强钢激光拼焊板焊缝组织及胀形性能分析

Microstructures and bulging formability of laser welded tailored blanks for high strength steel with unequal thickness

采用激光焊接方法,针对1.8mm厚的SAPH440与2.2mm厚的DP600高强钢实施激光拼焊.测试了不等厚拼焊板焊接接头的金相组织以及显微硬度,然后通过杯突试验对所得到的不等厚高强钢拼焊板的胀形性进行了研究,进一步与母材的胀形性相比较.结果表明,焊缝的金相组织为针状铁素体和板条马氏体,焊缝两侧硬度分布不同,焊缝处的硬度要高于母材.拼焊板的杯突值低于任何一侧母材的杯突值,焊缝的位置对不等厚拼焊板的胀形性有一定的影响,薄板所占比例越大拼焊板的胀形性越好,在胀形成形过程中焊缝向厚板侧移动.

Tailor welded blanks（TWB）of laser weld is adopted to weld high strength steel sheets SAPH440 with 1.8 mm thickness and DP600 with 2.2 mm thickness.The microstructures and microhardness of the welded joint for TWB are studied,and the cupping tests are carried out to study the bulging formability of TWB,which is compared with that of the original sheet blanks.The results show that the microstructures of the joint are acicular ferrite and lath martensite,the microhardness of the joint is higher than that of the base metal.And the cupping experimental values of TWB are lower than that of the original sheet blanks.Eventually,the weld location has some influence on the bulging formability of TWB,the bigger the proportion of the thin blank is,the better the bulging formability of TWB is,and the weld will move to the side of the thick blank during bulging formation.