镁铝异种金属搅拌摩擦焊搭接接头组织与性能分析

Microstructure and properties of dissimilar materials Mg/Al laped joint by friction stir welding

关键词:  搅拌摩擦焊  镁合金  铝合金  过渡层

Key words:  friction stir lap welding  magnesium alloy  aluminum alloy  conversion layer

摘要:

采用搅拌摩擦焊技术对异种金属铝合金5083和镁合金AZ31进行了搭接焊试验.对接头的力学性能、组织形貌及断口形貌进行了观察和分析.结果表明,在铝板置于上层、搅拌针长度小于铝板板厚的情况下,使用合适的工艺参数,这两种轻合金可以获得抗剪性能良好、界面结合紧密、无缺陷的搭接接头,从而使镁板和铝板通过由一定金属间化合物组成的界面区过渡层形成了良好的连接;接头都断裂于界面结合处,铝侧是由塑性撕裂导致的"小坑"组成,而镁侧主要为河流状花样;在界面中心区出现了明显的硬度升高现象.

Abstract:

5083 aluminum alloy and AZ31 magnesium alloy were lap jointed by using friction stir lap welding.The mechanical properties, microstructure and fracture appearance of the joint were investigated.The results indicated that a high shear strength, interface bonding and defect-free weld have been obtained when the probe of a tool did not contact the lower Mg sheet and the suitable welding parameters are used.5083 and AZ31 were jointed by a conversion layer that existed in interface zone which contained intermetallic compounds.The joints fractured in interface.Fractographs confirm that the fracture of the Al side is composed of the "small pit" by plastic tearing, but the fracture of the Mg side consists of river line pattern mainly.The micro hardness raised in the interface zone.