Interfacial microstructure evolution in fusion welding of immiscible Mg/Fe system

Abstract

Abstract Immiscible dissimilar metals can be successfully bonded by adding alloying elements to promote interfacial reaction. Although there are many kinds of interfacial microstructure, studies on the interfacial microstructure evolution are deficient under different bonding methods. In this work, AZ31 Mg alloy and Q235 steel were bonded by laser-tungsten inert gas (TIG) butt fusion welding with Ni interlayer. The microstructure and tensile properties were evaluated to understand the effect of laser offset on the interfacial microstructure and mechanical features of Mg/steel joints. The interfacial microstructure has undergone the evolution of eutectic, eutectic-free and eutectic with the increase of laser offset to steel side during double-side welding, which include the characteristics of fusion welding, brazing-welding and solid-state welding. The interfacial microstructure evolution design principle is discussed, some references can provide for the design method and procedure.