氧化膜对铝合金双光束激光搭接焊焊缝成形和气孔的影响

Effects of Oxide Films on Weld Formation and Porosity of Double Laser Beam Lap Joints of Aluminum Alloys

氧化膜对铝合金激光搭接焊有重要影响,但其影响机理尚不完全清晰。采用双光束光纤激光完成5754铝合金和7003铝合金的搭接焊,分别去除搭接处氧化膜及同时去除搭接面和工件上表面氧化膜,通过对比试验,分析了氧化膜数量和位置对搭接焊过程金属蒸汽特征谱线、焊缝成形和气孔缺陷的影响。结果表明,氧化膜对金属蒸汽特征谱线种类没有影响,AlO自由基谱线强度随氧化膜减少而略减弱。搭接界面及氧化膜阻碍熔池传热过程,易形成台阶状焊缝轮廓和夹层气孔,氧化膜聚集在搭接区附近和下板熔池中,匙孔失稳倾向升高,大尺寸工艺气孔数量增加。

Oxide film plays an important role in laser lap welding of aluminum alloy,but its effect mechanism is still not clear.The overlap welding of 5754 aluminum alloy and 7003 aluminum alloy was completed by double-beam optical fiber laser.The oxide film on the lap interface and the oxide film on the lap surface and top surface of workpiece were removed,respactively.The effects of amount and position of oxide film on the metal vapor characteristic spectrum,weld formation and pore defects during cap welding were analyzed through comparative experiments.The results show that oxide film has no effect on the type of characteristic spectrum lines of metal vapor,and the intensity of Al O radical spectrum decreases slightly with the decrease of oxide film amount.The lap interface and oxide film hinder the heat transfer process of the molten pool and lead to step-like weld contour and interlayer pore.The oxide film gathers near the lap interface and in the molten pool of lower plate.The instability tendency of keyhole increases,and the number of large pore increases.