铝/镁异种合金搅拌摩擦搭接焊接头界面结构及拉剪性能

Interface Structure and Tensile-Shearing Property of Dissimilar Aluminum/Magnesium Alloy Friction Stir Lap Welded Joints

在其它焊接条件相同的情况下,通过改变焊接速度对5A06铝合金和AZ31镁合金进行搅拌摩擦搭接焊接试验,分析焊接速度对接头hook沟成形及拉剪性能的影响。结果表明,适当降低焊接速度,有利于提高焊接热输入量和金属流动能力,使得接头的有效搭接厚度和宽度增加,内部孔洞缺陷消失。此外,有利于hook沟处铝和镁金属原子发生充分扩散,形成紧密的冶金结合。但是,当焊接速度太低时,热输入量过大,接头hook沟附近产生了明显的金属间化合物过渡区,且过渡区内形成了大量的Al_(12)Mg_(17)和Al_(3)Mg_(2)脆性金属间化合物,导致过渡区开裂。其中,当焊接速度为47.5 mm/min时,接头的有效搭接厚度和有效搭接宽度最大,且hook沟前端界面得到良好的冶金结合,使得接头的拉剪性能最优。

Under the same other welding conditions,friction stir lap welding of 5A06 aluminum alloy and AZ31 magnesium alloy was carried out by changing welding speed,and its influence on the formation of hook groove and tensile shearing property of the joints was analyzed.The results show that the heat input and flowability of plastic material are improved when the welding speed is reduced properly,and the effective lap thickness and width increase and the pore defects in the joint disapear.In addition,the interface between aluminum alloy and magnesium alloy near the hook groove is metallurgically bonded owing to sufficient atomic diffusion.However,when the welding speed is too low,the heat input increases dramatically and an obvious transition zone near the hook groove appears,and a large number of Al_(12)Mg_(17)and Al_(3)Mg_(2)brittle intermetallic compounds are formed in this zone,leading to many cracks.When the welding speed is47.5 mm/min,the largest effective lap thickness and width in the joint are obtained,and the interface in the front of the hook groove has a good metallurgical bonding,so the tensile shearing property of the joints is the best.