Patent attributes
The invention has a feature of comprising a butting process of forming a stepped butted portion and a joining process of performing friction-stir-welding on the stepped butted portion, wherein the rotary tool includes a base side pin having a taper angle larger than a taper angle of a tip side pin, and a pin step portion in a staircase shape is formed on an outer circumferential face of the base side pin, and wherein in the joining process, a rotation direction and a translation method of the rotary tool are set such that the second metal member is on an advancing side, a target angle by which a rotation axis of the rotary tool is inclined toward the second metal member is set such that a burr formed on a front face of the second metal member after the joining process has a thickness between 0 and 130 μm.
