Analysis of Friction Stir Welding Defects and Failure: A Preliminary Study

The present study aims to explore different types of uncommon defects in steel welding through friction stir welding as a solid-state welding technique. There are natural melting and solidification involved in the fusion welding process of steel that leads to several problems like residual stresses/distortions, formation of unfavorable microstructure, defects like porosity, hot cracking, hydrogen embitterment etc. Friction stir welding (FSW) is so-called free of most of these defects. Although there are many defects have been recorded after performing the friction stir welding of steel. These defects are quite different from those exposed in the fusion welding process. Different variable parameters of FSW including, welding speed, rotational speed of tools, tool tilt angles, pin length, pin diameters, shoulder characteristics, and process constraints are the different causes behind these types of defects. Many of these defects can be eliminated by optimizing the variable parameters, although the process is complex and challenging. Efforts have been made to discuss the different types of encountered defects and the causes behind them along with potential solutions to eliminate these defects.