为研究力学性能、耐蚀性和抗冲击性能都较好的车身用镀锌钢激光拼焊焊缝质量, 采用Nd: YAG脉冲激光器及数控加工系统对其进行激光拼焊试验。基于正交方案及极差分析法, 系统研究了各工艺参数对激光焊接接头质量影响的主次关系, 理论分析计算了试验条件下的因素水平最优组合及其估计值, 并从焊缝成形质量、接头力学性能和微观组织等方面针对优化前后试样的焊接质量进行了对比分析。结果表明, 工艺参数因素对试样抗拉强度的影响大小依次为焊接速度＞电流占空比＞气流量＞离焦量＞脉冲宽度; 经正交极差优化后的最佳参数组合为电流占空比Q＝39%, 脉冲宽度p=61 ms, 焊接速度v＝2.50 mm/s, 气流量q＝19 L/min、离焦量Δf＝－0.7 mm; 优化后的试样的焊缝表面成形质量更好、接头强度和硬度均有提高, 焊缝与热影响区的晶粒与组织也更细小致密。

In order to study the welding quality of galvanized steel of vehicle body with superior mechanical property, corrosion resistance and impact resistant performance, the laser welding of tailored blanks experiment was conducted with Nd: YAG pulsed laser and NC machining system. Based on the orthogonality scheme and range analysis method, this paper studied systematically the effect laws of primary and secondary of each technological parameter on welded joint quality of automobile galvanized steel, theoretically analyzed and calculated the optimal combination and estimated value of technological parameters and its level under this test condition, and made the contrastive analysis on the testpieces welding quality before and after optimization from the aspects of weld formation quality, mechanical property and micro-structure. The result indicates that under this test condition, the influence extents of technological parameters on tensile strength are, in order: welding speed, duty cycle of electricity, gas flow, defocusing amount, pulse width. The optimum parameter combination after orthogonal optimization is: the duty cycle of electricity＝39%, pulse width＝61 ms, welding speed＝2.50 mm/s, gas flow＝19 L/min and defocusing amount＝－0.7 mm. The optimized testpiece has a better weld formation quality and its joint strength and rigidity were increased. In addition, the crystal in weld joint and HAZ becomes smaller and denser.