A critical review on mechanical and microstructural properties of dissimilar aluminum (Al)-magnesium (Mg) alloys

Friction stir welding (FSW) is a solid-state welding process used to join aluminum and magnesium alloys. Their lightweight, high specific strength, ductility, low density, and many more properties make them superior to use in different industries such as automotive, shipbuilding, aerospace, etc. Friction stir welding (FSW) of aluminum-magnesium alloys of various grades has attracted significant scientific and industrial attention because of its ability to transform a product into a high-quality joint. In FSW, the plastic flow of the material under a rotating non-consumable tool is controlled by the base metal properties such as tensile strength, hardness, etc. The weld quality in FSW is determined by various process factors such as base metal position, welding speed, rotational tool speed, etc. This paper intends to provide a review of the work that has been carried out in the field of Al-Mg friction stir welding. The investigative technique is addressed by describing the joining mechanism, heat generation and the challenges encountered during Al-Mg unification. Further, observed trends in phase transformation, microstructural evolution, mechanical properties, tool design, and different theories related to Intermetallic compounds (IMCs) formation are analyzed. Finally, this work highlights the key findings of previous research and suggests future directions for welding aluminum-magnesium alloys using FSW.