中文摘要：

研究NaCI、ZnCl2、LiCl和KF等卤化物活性剂对激光焊接铝合金焊缝熔深的影响，发现卤化物活性剂能够使焊缝熔深明显增加。同时，运用高速摄像及光谱诊断的方法来分析卤化物活性剂对铝合金激光焊过程中等离子体温度、体积等物理参数的影响，并利用“双钨片”试验来分析卤化物活性剂对熔池金属流动状态的影响，以研究卤化物活性剂对增加焊缝熔深的作用机理。试验结果表明，卤化物活性剂的加入不仅能够降低激光焊等离子体的温度，使得等离子体对激光的散射、折射和逆韧致吸收减小，导致透过等离子体照射在试件表面的激光功率密度增大，使激光对试件的热输入增加，焊缝熔深增大；而且，卤化物活性剂的加入还会使熔池金属的流动状态发生改变，使得焊缝熔深增加。

英文摘要：

The effect of halide surfactant （such as NaCI, ZnCl2, LiC1, KF and so on） on the weld penetration of laser welding aluminum alloy is studied, and it is found that the halide surfactant can significantly increase the weld penetration. To study the mechanism that the halide surfactant is beneficial to fiercely increasing the welding penetration, the high-speed camera and technique of spectroscopic analysis is used to explore the influence of halide surfactant on physical parameter of plasma, such as temperature, volume and so on. And the experiment of two-sheet tungsten is conducted to explorer the influence of halide surfactant on flowage of welding pool. It is found that the halide surfactant can reduce the temperature of plasma, which leads to decrease the refection, scattering and inverse bremsstrahlung absorption of laser in the plasma, and increase the input of laser to workpiece. And the halide surfactant can change the state of circulation in the weld pool and make the penetration deepen.