Studies on Microstructure and Mechanical Properties of GTAW, Laser and Friction Stir Welded ZM21 Magnesium Alloy

Present work pertains to welding of ZM21 magnesium alloy using three different welding techniques namely Gas Tungsten Arc Welding, Laser Beam Welding and Friction Stir Welding. After careful trial and error method, the process parameters were identified to produce defect free, full penetration welds successfully. The microstructure and mechanical properties of ZM21 magnesium alloy using GTAW, LBW and FSW processes were analyzed by optical microscopy, tensile testing and Vickers micro hardness measurements. The results show that the tensile properties of Friction stir welds and Laser beam welds are much better than those of gas tungsten arc welds. The formation of very fine grains in the friction stir welded region and absence of HAZ in LBW are found to be main reasons for better tensile properties. It has been concluded that the ZM21 magnesium alloy exhibits good weldability in all the three welding processes and laser beam welding process offers higher joint efficiency when compared with GTAW and FSW.