Patented by The Welding Institute in Cambridge, UK, it was initially developed for joining aluminum alloys. It is a solid-state joining technique that is energy efficient, environmentally friendly, and versatile. It is considered to be the most significant development in metal joining in the last decade. The basic concept of friction stir welding is relatively simple. A rotating tool consisting of a penetrating pin and a surface contacting shoulder is inserted into the material to be joined and traversed along the line of the joint.
Localized heating is generated by friction between the tool and the workpiece.
A welded joint is produced by displacement of material from the leading area of the pin to the trailing area.