Effect of Al foils interlayer on microstructures and mechanical properties of Mg–Al butt joints welded by gas tungsten arc welding filling with Zn filler metal

Gas tungsten arc butt welding of Mg–Al filling with Zn filler metal without and with Al foils in different thicknesses was carried out. Additional Al element was introduced into the fusion zone to accurately modulate microstructure and composition of the welding seam. Microstructures and mechanical properties of the welded joints were examined. Results show that the addition of appropriate quantity of Al element increases the content of Al-based solid solution in the fusion zone near the Mg base metal. The solid solution can eliminate the stress concentration and hinder crack propagation, so the tensile strengths of the joints are improved. However, the immoderate quantity of Al element will lead to the formation of partially Al-rich zones and deteriorate the mechanical property of the joints.

► Butt joining of Mg alloy to Al alloy is realized by GTA welding.
► Additional Al element was introduced into the fusion zone.
► The composition and microstructure of the welding seam are accurately modulated.
► The tensile strength attains 104 MPa.