Friction-based welding processes: friction welding and friction stir welding

Friction-based welding processes are considered as very efficient solid-state metal joining processes due to soundness of the welded joint with remarkably less energy consumption and environmentally friendly. The terminology behind these processes is to make use of elevated temperatures caused by the mechanical friction at contacting surfaces to fuse materials together. Several different friction-based welding techniques are classified briefly explaining their mechanisms to show a comparison between friction welding (FRW) and friction stir welding (FSW). In FRW contact between the specimens itself induce friction, while FSW uses a non-consumable rotating tool to fuse material at the junction. Numerous advantages and drawbacks exhibited by both the processes are compared by overviewing the current researches. Also extensive focus on the various factors influencing the properties of FSW joints such as rotational speed, welding speed, axial force, tool geometry, and defects are studied. FSW displayed superiority in welded joints as regards adaption to modern technologies, optimized process parameters, and the ability to join a wide variety of dissimilar metals and alloys.