| 摘要 |
PROBLEM TO BE SOLVED: To increase joining strength more than a conventional level and also to prevent generation of cracks, in the case of joining a valve seat to the circumferential part (joining face part) of a port opening in a cylinder head main body. SOLUTION: A brazing filler metal layer 7 is formed preliminarily on the surface of a valve seat 3 through a diffusion joining layer 5 between the brazing filler metal and the valve seat 3. While the valve seat 3 and a cylinder head main body 2 are pressurized, energizing and heating are performed at an initial current value until the valve seat 3 is embedded at a prescribed joining position, a fusion reaction layer 6 of the brazing filler metal and the cylinder head body 2 is formed and while the fused brazing filler metal is discharged from the joining face between the both members 2, 3, the both members are joined in a liquid phase diffused state through the diffusion joining layer 5 and the fusion reaction layer 6. Subsequently, the energizing and the heating are performed at slow cooling current value smaller than the initial current value, the both members 2, 3 are cooled slowly and the temperature difference is made smaller. |
