Effects of cu addition on microstructure characteristics and tensile behaviors of metal inert-gas arc welded mg-steel dissimilar joints

Abstract

The joining of AZ31B Mg alloy to Q235 steel was realized by metal inert-gas arc welding. Microstructure characteristics and tensile behaviors of Mg-steel joints with and without Cu addition were investigated and compared. Results show that the microstructure and tensile strength were improved with the addition of Cu interlayer. The IMC Mg2Cu with rod-like structure was generated in both the whole weld zone and Mg/steel interfacial zone. The maximum tensile strength of Cu-added joint can reach to 185 MPa, which partly fractured at the weld seam of Mg alloy instead of the Mg/Fe interface. The increase of the joint strength and microhardness profile with addition of Cu can be explained in terms of improvement of wettability of Mg alloy to steel and the formation of fine IMC Mg2Cu.