Effect of Travel Speed on Quality and Welding Efficiency of Friction Stir Welded AZ31B Magnesium Alloy

Weight reduction is one of the most concerning issues of automotive and aircraft industries in reducing fuel consumption. Magnesium (Mg) alloys are the lightest alloys which can be used in the structure due to low density and high strength to weight ratio. Developing a reliable joining process of magnesium alloys is required due to limited ductility and low workability at room temperature. Friction stir welding (FSW) is a solid-state welding process that can be performed to produce sound joints in magnesium alloys. Researchers have performed investigations on the effect of rotation and travel speeds in FSW of AZ31B magnesium alloy. However, there is lack of study on the FSW parameters, i.e. travel speed below 50 mm/min and rotation speed lower than 1000 rpm. In this research, FSW of AZ31B magnesium alloy was performed at a constant rotation speed of 700 rpm and varied travel speeds below 50 mm/min. The results showed the development of finer grain size in stir zone with increasing of welding travel speed from 20 mm/min to 40 mm/min. It was found that the finer grain size improved the mechanical properties while maintaining the elongation at different welding parameters.