The effect of water cooling during dissimilar friction stir welding of Al alloy to Mg alloy

Formation of intermetallic compounds in the stir zone of dissimilar welds affects the mechanical properties of the joint significantly. This research demonstrates the use of submerged friction stir welding (SFSW) under water as an alternative and improved method for creating fine grained welds, and hence, to alleviate formation of intermetallic phases. A constant tool rotation rate of 300 rpm and travel speed of 50 mm/min was used. The air welded specimen had a relatively larger volume fraction of intermetallic compound, higher peak temperature in stir zone and significantly higher hardness in the weld center. The present study suggests that submerged friction stir welding under water resulted in lower peak temperature and because of lower heat input intermetallic compounds formation was limited.