目前,汽车用镀锌钢板的搭接多采用电阻点焊技术,新型激光点焊技术——激光螺旋点焊以其高效率、高柔性的特点有望逐渐替代电阻点焊。研究了搭接间隙对激光螺旋点焊焊点成形与力学性能的影响,分析了不同间隙下高压锌蒸气的逃逸过程和缺陷的成因。研究结果表明:对于单层1.8 mm厚、6.7 mm焊点直径的ST12镀锌钢板搭接接头,激光螺旋点焊的间隙适应性较好,在0.2~0.4 mm的板间间隙内都可以获得成形良好、力学性能较好的焊点;当间隙大于0.1 mm时,可以有效避免锌蒸气逃逸造成的焊接缺陷;在间隙约为0.2 mm时,锌蒸气能够顺利逃逸,从而获得最佳的表面成形和力学性能。

Currently, spot welding technology is widely used in the overlap welding of galvanized steel plates for automobile applications. However, the novel laser screw welding technique is expected to gradually replace resistance spot welding because of its high efficiency and flexibility. In this study, the effects of inter-sheet gaps on the formation and mechanical properties of laser screw welding joints are investigated. The escape process of high-pressure zinc vapor and the causes of defects are analyzed at different gaps. For ST12 galvanized steel welded joint with 1.8 mm thick single-sheet and 6.7 mm spot weld diameter, this new technique offers an overlap gap window of 0.2--0.4 mm, suggesting wide adaptability for inter-sheet gaps. Using a gap greater than 0.1 mm, welding defects caused by the escape of zinc vapor can be effectively avoided. The best weld appearance and mechanical properties can be obtained at a gap of 0.2 mm because of the fluent escape of zinc vapor.