采用激光焊与激光-MIG复合焊两种打底焊方式和激光-MIG复合焊与MIG(熔化极惰性气体)保护焊两种填充焊方式进行两两组合,完成了15 mm厚316L奥氏体不锈钢的焊接。对各试验组焊接接头的显微组织和力学性能进行了研究,结果表明,采用全激光-MIG复合焊得到的焊接接头成形最优。激光-MIG复合焊焊层中心部位存在胞状晶组织,而MIG焊焊层几乎全为柱状晶结构。复合焊填充层的拉伸强度高于MIG焊填充层,而激光打底层与复合打底层强度相当,所有断裂均为韧性断裂。两种打底焊层焊缝中心显微硬度均高于母材,复合填充焊层焊缝中心显微硬度略高于母材,MIG焊填充焊层则低于母材。

The methods of underlying welding including laser welding and laser-MIG hybrid welding in combination with methods of filling welding including laser-MIG hybrid welding and MIG welding(melt inert-gas welding),are used to complete the welding of 15-mm-thick 316L austenitic stainless steel. The microstructure and mechanical properties of the weld joints in each group were studied. The results show that the weld joint obtained by all laser-MIG hybrid welding has the best formation. There is cellular structure in the center of laser-MIG hybrid welding layer, while the MIG welding layer is almost all columnar crystal structure. The tensile strength of the filling layer welded by hybrid welding is higher than that welded by MIG, while the strength of the underlying layer welded by laser is comparable to that welded by hybrid welding, and all fractures are ductile fractures. The micro-hardness of the weld center of the two different underlying layers is higher than that of the base metal, the micro-hardness of the weld center of the hybrid welding filling layer is slightly higher than that of the base metal, and the micro-hardness of MIG filling layer is lower than that of the base metal.