Friction welding achieves 100 per cent metal-to-metal joints, giving parent metal properties. The process involves making welds in which one component is rotated relative to, and in pressure contact, with the mating component to produce heat at the faying surfaces.

Softened material begins to extrude in response to the applied pressure, creating an annular upset. Heat is conducted away from the interfacial area for forging to take place.

The weld is completed by the application of a forge force during or after the cessation of relative motion. The joint undergoes hot working to form a homogenous, full surface, full diameter, high-integrity weld.