Friction stir processing is a processing method evolved from friction stir welding, also known as friction stir treatment.
The basic principle is that the material to be processed undergoes severe plastic deformation, mixing and crushing through the strong stirring action of the stirring head, so as to realize the densification, homogenization and refinement of the microstructure. Friction stir machining can eliminate defects such as shrinkage porosity and shrinkage cavities in cast products, and can also refine grains, thereby improving material properties.
Friction stir welding technology was invented by the British Welding Research Institute in 1991, and applied for an invention patent in the UK the following year, and applied for patent protection in countries around the world. Since the patent protection and publication, friction stir welding technology has been widely used first and mainly in the field of light metal structures such as aluminum alloys and magnesium alloys and has also achieved certain development in the field of high melting point materials.
In addition to the advantages of ordinary friction welding technology, friction stir welding can also connect various joint forms and different welding positions. Norway has established the world's first commercial friction stir welding equipment, which can weld Al ship plates with a thickness of 3-15 mm and a size of 6x16; It is used to weld certain rocket components; McDonnell Douglas also uses this technique to make the propellant tanks for the Delta launch vehicle.