Method for friction stir welding, jig therefor, member with friction stir-welded portion, and tool for friction stir welding

摘要

A recess portion with a substantially circular cross-section is provided in the upper end surface of a supporting jig. When a probe of a device for friction stir welding is buried in the upper end surface of a layered portion, material in the vicinity of the buried portion flows plastically. This causes the plastically flowed material to flow into the recess portion, and as a result, the material is stirred in a relatively large region. When the material that flowed into the recess portion is cooled and solidified, a friction stir-welded portion-possessing member having a projection portion is obtained.