| abstract |
A tool (1) of the present invention for friction stir welding includes a base material (2) and a coating layer (3) formed on that base material (2). The coating layer (3) is characterized by being formed from two or more layers, the coating layer (3) as a whole having a heat permeability of 8000 J/s 0.5 ·m 2 ·K or less, at least one of the layers in the coating layer (3) including a hexagonal crystal system and/or a noncrystalline form, at least one of the layers in the coating layer including a cubic crystal system, and the coating layer (3) having compressive stress. |