Friction stir welding

Friction stir welding (FSW) is a solid-state joining process: a rotating non-consumable shouldered tool with a profiled pin plunges into the joint line and traverses it, the friction heat softening the metal below its melting point so the pin stirs the two sides into a forged bond. There is no melting, no filler, and no shielding gas, so aluminum joins without the porosity, solidification cracking, and softening of fusion arc welds. The process is the standard for aluminum hull panels, helideck and superstructure extrusions, and prefabricated stiffened panels, joining 5083 and 6082 marine grades. FSW gives low distortion and weld strength near the parent, qualified to ISO 25239 for the railway and marine sectors.