Investigation on weldability of magnesium alloy thin sheet T-joints: arc welding, laser welding, and laser-arc hybrid welding

Four welding methods, including laser welding, gas tungsten arc (GTA) welding, laser–GTA hybrid welding, and laser–GTA hybrid welding with cold welding wire, are used to investigate the weldability of T-joints of magnesium alloy thin sheet. Stake welding process is presented in this paper in order to overcome the defects, such as stress concentration and deformation, and improve the accessibility of T-joints in fillet welding process. The effect of heat source type on weldability of T-joints is analyzed. The microstructures and mechanical properties are investigated. Experimental results indicate that comparing with the other three welding methods, laser–GTA hybrid welding with cold welding wire is the most effective process for T-joints of magnesium alloy thin sheet. In this process, T-joints are full penetration and the toes are smooth and round, and besides, reinforcement forms on the upside of weld bead by the filled wire. The mechanical properties of T-joints made with laser–GTA hybrid welding with cold welding wire achieve 90 % of that of base metal and are superior to that without welding wire.