Forge welding turns full circle: friction stir welding of steel

Friction stir welding (FSW) has been shown to have many benefits, in terms of both the weld itself and the economics and ease of application of the welding process. An FSW tool must be able to maintain its strength at the softening point of the material being welded, be chemically inert to that material at elevated temperature, have resistance to bending and rotating fatigue stresses, be capable of being machined to complex shapes and ought not to fail unpredictably. Friction stir welding of steel has been shown to be technically possible, capable of producing welds whose properties can exceed those of fusion processes and is a technique that is demonstrating a useful degree of industrial robustness. The FSW process in steel also shows indications of being tolerant to poor weld preparation and the presence of defects. FSW's ability to produce excellent welds underwater, and also to produce welds that are likely to be tolerant of radiation induced damaged, is also generating considerable interest in the marine and nuclear engineering communities.