Experimental evaluation of wear features of W-25%RE pin tool used in friction stir welding mild steel

This paper presents the results of studying butt welding of 4 mm thick mild steel plate with a W-25% Re pin tool using the relatively new friction stir welding (FSW) process. The study includes investigating the wear behavior of the pin tool and the effects of process conditions such as rotational speed on the quality of the weld, microstructures and hardness of mild steel. The results reveal that the traverse (welding) force increases with the increase in the traveled distance of the pin tool, whereas torque decreases with the increase in the travelled distance of the pin tool. The tool has shown wear resistance at lower rotational speed, but with the increase of the rotational speed, wear of the tool became prominent. All welded samples revealed grain size refining. Furthermore, at high rotational speed martensitic structure phase developed due to phase transformation. Different distinct regions of stir zones, thermomechanical heat affected zones and heat affected zones were present in the weld.