Friction Stir Welding technique is the advanced technique for joining of dissimilar materials such as titanium to stainless steel which are otherwise difficult to join. The Friction Stir Welding technique is already gaining momentum for welding of difficult to weld Aluminium alloys in various industries such as ship building, transport, automotive and even space. The process though offers certain advantages over the conventional welding techniques, it also suffers from the plastically deformed thermo-mechanically affected zone as against normally claimed. Besides, the workpieces must be rigidly clamped to withstand the movement of high rotational speed of tool, resulting in residual stresses and sometimes, even distortion. The technique is quite beneficial especially for joining of dissimilar materials, and materials difficult to weld, it has the drawback of leaving keyhole at the end of each weld. However, these problems could be studied and solved for their solutions.
Such has been the interest in friction stir welding that considerable effort is being made in transferring the technological benefits from aluminium and magnesium to higher temperature materials such as copper, titanium and steels, which are used in diversified applications. It could demonstrate the feasibility of joining/welding the dissimilar materials (titanium to SS). However, specific tool designs are required to be made for each type of joints.