Study on the weld joint of Mg alloy and steel by laser-GTA hybrid welding

A laser-GTA hybrid welding technique was chosen to study the weld of the dissimilar alloys of AZ31B Mg alloy and 304 steel. A lap joint was formed between the two. The weld penetration, which determines the mechanical properties of the welded joints, depends on the laser power. A transition zone formed at the interface of the Mg–Fe during laser-GTA hybrid welding and Mg element diffused into the Fe matrix by forming oxides and reacting in the transition. During tensile testing, the joints fractured at the interface between the Mg alloy and the steel. Metallic oxides produced at the Mg–Fe interface were the reason for the poor mechanical properties of the weld joints.