| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a titanium alloy joined part having a high shock absorbing energy by means of friction stir welding at a &bgr;-transus temperature or more of a titanium alloy at which a burden to a rotation tool and a welding load lessen.SOLUTION: A joining method of titanium alloy materials is provided which comprises: a friction stir welding step of causing two titanium alloy materials 6, 8 to face each other at a part to be joined, force-fitting a rod-like rotation tool 12 rotated at a prescribed rotation speed to the part to be joined, thereby joining two titanium alloy materials; and a structure observation step of measuring a lamella width of a stirring part structure formed by the friction stir welding step. When the lamella width measured in the structure observation step is less than 0.2 μm, a friction stir welding step accompanied by a change in joining conditions which contributes to an increase in heat input to the part to be joined or an increase in cooling speed is further performed, and the friction stir welding step and the structure observation step are repeated until the lamella width amounts to 0.2 μm or more. |
