激光摆动模式对铝/钢焊接接头成形特征及组织、强度的影响

铝、钢金属在物理化学性质上的巨大差异使得铝/钢异种接头的优质连接成为焊接领域的难点。采用摆动激光热源实现了6061铝合金和316L不锈钢搭接接头的良好连接,研究了激光摆动模式、摆动频率对接头成形质量、界面组织结构及拉剪强度的影响。结果表明:摆动激光能够增加铝/钢界面的连接面积,减小接头的熔深,有效抑制焊缝中的气孔、裂纹等缺陷;同时,摆动激光能使界面温度均匀并增强对熔池的搅拌作用,降低界面处的冶金反应,有效抑制界面脆硬金属间化合物的产生;摆动激光焊接接头的界面组织主要为Fe(Al)固溶体及少量弥散分布的针状FeAl3相;摆动激光焊接接头的最大拉剪强度可达117.5 N/mm,相比于常规激光焊接接头提高了约45%,接头断裂位置为不锈钢与焊缝交界处。

Effects of Laser Beam Wobble on Weld Formation Characteristics,Microstructure,and Strength of Aluminum Alloy/Steel Joints

The high-quality welding of aluminum alloy/steel dissimilar alloys is difficult owing to the great variation in their physical and chemical properties.In this work,the laser beam wobble welding process is adopted to achieve good connection between 6061 aluminum alloy and 316 L stainless steel.Moreover,the effects of laser wobble mode and wobble frequency on weld formation characteristics,microstructure,and tensile-shear strength have been investigated.The results indicate that laser wobble welding can increase interfacial bonding area,decrease weld penetration,and effectively suppress weld pores and cracks.Laser wobble can make the interfacial temperature uniform and enhance the stirring effect on the weld pool;it also alleviates metallurgical reactions and suppresses the formation of brittle intermetallic compounds.The interfacial microstructures in a welded joint obtained with wobble laser mainly comprise Fe(Al)solid solution and a small amount of FeAl3 phase;the maximum tensile-shear strength of the joint obtained with the wobble laser can reach 117.5 N/mm,which is 45%more than that of conventional laser welding.Welded joint fractures are also observed at the interface between stainless steel and the weld metal.