| 摘要 |
PURPOSE:To reduce the dispersion of filling material and increase the wear resistance of the valve face by subjecting the valve to aging traatment at a specific temperature and a specific time after the filling operation, in the valve filled with a surface hardening filling material at the valve face part. CONSTITUTION:An engine valve 1 is made from a heat resisting alloy such as a chrome steel as a mother material 1a, and is constituted by a rod-shaped shaft and a disc-shaped bevel part 3 which are integrally provided. A filling groove 4 is provided on the side of the shaft 2 at the peripheral edge of the bevel part 3, and a filling part 5a provided by welding a cobalt group filling material as a surface hardening filling material. In the foregoing, after forming the filling part 51, the valve 1 is held in a temperature range of 700-900 deg.C for one hour or more to carry out aging treatment. Thereafter, the filling part 5a is ground as heretofore to complete the valve 1. By this aging treatment, separation of carbide within the filling material is accelerated, and the quantity of carbides is approximated to the saturation state, and the hardness of the filling material is stabilized. |
