Friction stir welding method with prior welding of a buildup bead by using a buildup member

摘要

The invention provides a friction stir welding method with less weld defects upon welding a butted portion between a first member (80) and a second member (90). A first member (80) is butted against a second member (90), and then a round-bar buildup member is pressed against the upper surface of the butted portion and rotated to weld a buildup bead (35) thereon. The buildup bead (35) corresponds to a projection of the prior art friction stir welding method. Next, a pin (51) of the rotary tool (50) is inserted to the butted portion to perform friction stir welding. According to this method, the buildup bead (35) corresponds to a projection and fills the space formed to the butted portion, so a good weld joint is formed and the generation of defects is suppressed.