PROBLEM TO BE SOLVED: To provide a friction stir welding method or the like, capable of performing welding with high bonding strength by sufficiently stirring materials and suppressing the movement of an overlapped interface in the outer periphery of a plastic flow area.;SOLUTION: The tool is pressed onto an overlapped portion where two workpieces are overlapped from the surface of the surface-side workpiece with rotation to generate the plastic flow area in the two workpieces. At that time, a first plastic flow area is generated for the surface-side workpiece free from the overlapped interface of the two workpieces to plastically flow with a convection in the plate thickness direction, and a second plastic flow area is generated for the overlapped interface and the reverse-side workpiece to plastically flow with a convection opposite to that in the first plastic flow area in an oblique direction inclined from the plate thickness direction, whereby the two workpieces are friction stir-welded while suppressing the plate thickness-directional movement of the overlapped interface in the outer periphery of the plastic flow area.;COPYRIGHT: (C)2013,JPO&INPIT
展开▼
