This article discusses three distinct mechanisms of bonding for solid-state (forge) welding processes, namely, contaminant displacement/interatomic bonding, dissociation of retained oxides, and decomposition of the interfacial structure. It explains the processes that can be characterized as having two stages: heating and forging. The article also includes a table that illustrates weld strengths as a function of annealing temperature for a range of materials.

Friction welding (FRW) is a solid-state welding process in which the heat for welding is produced by the relative motion of the two interfaces being joined. This article provides an outline of the mechanisms of...