采用超窄间隙激光焊对100 mm厚304奥氏体不锈钢进行了焊接试验,并研究了接头的显微组织和力学性能。结果表明,超窄间隙激光焊可以实现百毫米级及以上厚板的有效连接且焊缝的成形良好。接头的显微组织由奥氏体和少量铁素体组成,晶粒呈胞状和等轴状。接头的拉伸强度为658 MPa。拉伸断裂位于焊缝的胞状晶区,断裂形式为典型的延性断裂,断口形貌为细小均匀的韧窝和撕裂棱。焊缝组织中等轴晶区的显微硬度大于胞状晶区。

The 100 mm thickness SUS304 stainless steels are welded by the ultra-narrow gap laser welding, and the microstructures and mechanical properties of the joints are analyzed. The results show that the hundred-millimeter-grade thickness plates can be effectively welded by the ultra-narrow gap laser welding and the welds present good surface appearances. The microstructures of the joints are composed of austenite and small amount of ferrite, and the grains are with the cellular equiaxed shapes. The tensile strength of the joints is 658 MPa and the tensile fracture is located at the cellular grain zone near the fusion line. The fracture morphology shows fine equiaxed dimples and tearing ridges, which indicates that the fracture is ductile. The microhardness at the equiaxed grain zone is obviously higher than that at the cellular grain zone.