Friction stir and pulsed current gas metal arc welding of AZ61A magnesium alloy: A comparative study

AZ 61A magnesium alloy plates were welded by friction stir welding (FSW) and Pulsed current gas tungsten arc welding (P-GTAW). The effect of welding processes on mechanical properties of AZ 61A welded joints was analyzed using on optical microscopy, scanning electron microscopy, tensile testing and Vickers microhardness measurements. The results show that the mechanical properties of FSW welded joint are much better than those of P-GTAW welded joint; the strength coefficient of FSW joint is 84%. Moreover, tensile strength and yield strength of FSW joint are 12% and 18% higher than those of P-GTAW joint, respectively. The improvement in the strength is attributed to the cold worked microstructure produced in the alloy during FSW. Due to the low welding temperature during FSW process and the excellent thermal stability of Al12Mg17 particles, the cold worked microstructures were well preserved. In addition, the FSW joint have asymmetric microstructures and mechanical properties, which are not observed in P-GTAW welded joint.