关键词: 不锈钢, 激光焊接, 搭接, 轨道交通

Abstract: Partial penetration lap laser welding was used for 301L-H stainless steel train bodies to solve the heats and the weld distortion problems. The effects of focused laser spot diameter and welding parameters were investigated with using fiber laser. Relationship among processing parameters and welding quality index like formation quality, heat trace on the surface, penetration shape and shear tensile performance, were concluded. The principles and methods were discussed for the selection of optimized parameters. For the combination of 0.8mm and 1.5mm high tensile strength plates, which were typically used for light weight train bodies, the outputs of laser machine should be over 2kW, and the focused spot diameters should be over 0.4mm if a large processing window was obtained to satisfy both appearance and mechanical requirements. For fiber laser with 0.4mm spot diameter, the penetration should be less than 1.4mm to make the outside surfaces no heat traces, and the fusion width in the interfaces between inner and external plate should be more than 0.8mm to make the tensile strength higher than that of resistance spot welding. For 301L-H stainless steel with tensile strength over 930MPa, the fractures are always located in the fusion zones at the interfaces between inner and external plates, so the tensile capacity is linearly related to the fusion widths in the interfaces.

Key words: stainless steel, laser welding, lap joint, railway transport