Abstract
Over twenty years has passed since the friction stir welding was developed. During this period, various improvements and developments have been made, and this method has been put to practical use in a very wide range of industry. Because, in this method, the welding is performed in a solid state, and a refined microstructure is formed due to severe plastic deformation by the rotation tool, a variety of excellent joint properties is obtained, and in some cases, the joint strength exceeds that of the base material. However, at present, this method is put to practical use only for light metals such as Al alloys. Accordingly, the friction stir welding technology of high melting point materials such as steel has been strongly desired. Based on the current status, in this paper, prospects of the friction stir welding technology are discussed.
