【摘要】 为了研究预热对铝合金搭接激光焊的影响,使用Nd:YAG激光器和1.4mm厚的5A03H24铝合金板材,分别在无预热和预热300℃条件下进行了搭接激光焊试验。结果表明,预热可在熔深、熔宽、热影响区宽度和拉剪力基本不变的同时大幅度提高焊接速度。预热高速焊接与无预热激光焊相比,焊缝中Mg元素质量分数无显著区别;拉伸断口显微组织都属于微孔聚集型塑性断裂;焊缝组织都由柱状枝晶和等轴树枝晶组成,并且熔合线附近的柱状枝晶组织相近;焊缝和母材硬度比无预热时有所下降,其中焊缝下降幅度大于母材。更多还原

【Abstract】 In order to investigate the effect of preheating on the laser lap welding,Nd:YAG laser and aluminum alloy 5A03H24 plate of 1.4 mm thick are used to carry out experiments of laser lap welding without preheating and with preheating at 300 ℃ respectively.The results indicate that preheating can accelerate welding speed greatly while the penetration depth and width,heat affected zone width and tensile shear strength are basically unchanged.Compared with laser welding without preheating,Mg element concentration in weld is almost the same during high speed welding with preheating.The tensile fracture microstructures are all micro-void coalescence type plastic fractures.The weld structures are all composed of columnar dendrites and equiaxial dendrites,and the columnar dendrites near fusion line are similar in structure.However,the hardness of weld and base metal is decreased,and the former decreases more in hardness than the latter.更多还原