Fusion Welding of Magnesium Alloys: Process Variants, Metallurgical Challenges, and Structure–Property Relationships—A Critical Review

The automotive and aero sectors seek lightweight high-strength materials for enhanced structural efficiency. Magnesium (Mg) alloys are used in defense, space, transportation, the electronic industry, and the biomedical field because of a good combination of properties viz., light weight, good specific stiffness, specific strength, processability, biocompatibility, good damping etc. Mg alloys are used in the cast and wrought forms, depending on the property demands, service requirements and cost. In addition, they are currently contemplated for non-loaded engineering structural applications. Many of these require the joining of Mg alloys, and it is timely to review the significant developments in the fusion of Mg alloys. Gas tungsten arc welding (GTAW) has often been preferred for Mg alloys because of its adaptability, stability, and economy. GTAW has various variants and a few advanced technologies. In addition, power beam processes provide some advantages amidst the challenges. The literature on fusion welding of Mg alloys is reviewed, focusing on the process / technology capabilities, effect of process parameters on the metallurgical transformation/ microstructural evolution and the resultant properties. Research gaps are identified relevant to the industrial needs to leverage the newer technologies to obtain quality weld joints also with view to achieve increased productivity and leveraging the capabilities for repair welding.