Steel Science Portal

Recently, friction stir welding (FSW) has been widely used in various fields. However, the tool wear and adhesion of the workpiece on the tool surface are serious problems. In the field of cutting tools, hard thin films were coated on the tool surface to improve the life and cutting performance of the tool. To address the problem of FSW, hard thin films such as TiN, TiAlN, TiSiN, TiBON, CrN, CrSiN and AlCrSiN were coated on the welding tools. And the relation between the wettability of these films and the process torque during FSW and quality of the finished surface was examined.
The wettability of pure iron and hard thin films was determined using a sessile drop method by focusing on the contact angle. The process torque during FSW was measured through the joining of low carbon steels. The process torque was significantly different depending on the type of the hard thin film. A clear correlation was observed between the wettability and the process torque. The result suggested that the tool performance for FSW can be evaluated by the wettability.