研究了保护气体中O2含量对CO2激光-熔化极气体保护(GMA)复合焊焊缝合金元素均匀性和熔池流动行为分布的影响规律。结果表明,焊接方向为激光在前时,电弧保护气体中O2含量对复合焊焊缝均匀性具有明显的作用。保护气体中O2体积分数含量达到2%以上时,复合焊焊缝中合金元素的分布基本均匀。对于He-Ar惰性保护气体,在小孔后沿的熔池区域形成了外向流动;而当保护气体中O2含量达到2%以上时,熔池流动为内向流动。保护气体中O2含量对焊缝合金元素分布的影响规律主要取决于Marangoni对流。当电弧保护气体加入大于等于2%O2时,Marangoni对流方向由外向流动变为内向流动,促进了整个熔池的内向流动,获得了合金元素的均匀分布。 The influence of O2 content in shielding gas on the homogeneity of alloying elements and the flow behavior of molten pool in CO2 laser-GMA composite welding was studied. The results show that when the welding direction is the first laser, the content of O2 in the arc shielding gas has a significant effect on the uniformity of the composite welding seam. When the volume fraction of O2 in the shielding gas reaches more than 2%, the distribution of alloying elements in the composite welding seam is basically uniform. For He-Ar inert protective gas, outward flow is formed in the weld pool area at the trailing edge of the orifice, while when the content of O2 in the protective gas reaches above 2%, the melt flow is inward flow. The influence of O2 content in protective gas on the elemental distribution of weld alloy mainly depends on the Marangoni convection. When the arc shielding gas is added at 2% O2 or more, the convection direction of Marangoni turns from outward flow to inward flow, which promotes the inward flow of the molten pool and obtains uniform distribution of alloying elements.