ABSTRACT
This chapter introduces the state of friction stir spot welding (FSSW) technology along with recent developments related to the joining mechanism of microstructure development and its mechanical properties. FSSW occurs mainly in three stages: plunging, stirring, and retraction. The tools used for FSSW typically consist of two parts: a pin or probe, and a shoulder. Material flow amid the FSSW is regularly explored utilizing tracer material strategies. The age-hardened alloys in general experience a higher degree of softening in the weld zone during friction stir welding or FSSW because of the dissolution and/or coarsening of the strengthening precipitates due to the annealing effect than those that have been solution treated and/or strain hardened. Friction spot welding, also referred to as refill FSSW, happens to be a relatively new-fangled solid-state linking process that is a viable substitute for creating dissimilar overlap spot joints.
