Laser welded–brazed Al/steel lapped joint was successfully obtained under various shielding gas contents (pure Ar, CO₂+Ar and pure CO₂) with laser power of 2000W. Influence of shielding gas contents on weld formation, interfacial microstructure and tensile–shear strength was investigated. The addition of CO₂ in the shielding gas would not only enhance the total fusion volume but also improve the wettability of molten filler. Interfacial microstructure observations showed that addition of CO₂ in the shielding gas would thicken the interfacial IMC. Continuous layered η–Fe₂(Al,Si)₅ and serration shaped θ–Fe(Al,Si)₃+τ₅–Fe_1.8Al_7.2Si was newly formed. In addition, higher peak temperatures were produced with the increase of CO₂ volumes, which was proven by numerical simulation results. Higher laser energy absorption for CO₂, alternation of melt flow pattern and smaller thermal conductivity of CO₂ were responsible for these changes. Highest average tensile–shear strength of 163MPa was obtained under the shielding gas content of 50 %Ar+50 %CO₂ when laser power was 2000W.

在2000W的激光功率下，成功地获得了在各种保护气体含量（纯Ar，CO ₂ + Ar和纯CO ₂）下的激光焊接钎焊Al /钢搭接接头。研究了保护气体含量对焊缝形成，界面组织和拉伸剪切强度的影响。在保护气体中添加CO ₂不仅会增加熔化总量，而且会改善熔融填料的润湿性。界面微观结构观察表明，在保护气体中添加CO ₂将使界面IMC增稠。连续层状η -铁₂的（Al，Si）的₅和锯齿形θ -铁的（Al，Si）的₃ +τ ₅ -Fe新形成了_1.8 Al _7.2 Si。另外，随着数值的增加，随着CO ₂体积的增加，产生了更高的峰值温度。对于CO更高的激光能量吸收₂，熔体的流动交替图案和CO的小的热导率₂负责这些变化。当激光功率为2000W时，在保护气体含量为50％Ar + 50％CO _2的情况下，最高平均抗剪强度为163MPa 。