| 摘要 |
An exhaust valve for an internal combustion engine including a movable spindle with a valve disc of a nickel-based alloy which also constitutes an annular seat area at the upper surface of the valve disc. The seat area abuts a corresponding seat area on a stationary valve member in the closed position of the valve. At manufacturing, the seat area of the valve disc is subjected to a thermo-mechanical deformation process at a temperature lower than or around the recrystallization temperature of the alloy. The seat area on the upper surface of the valve disc has been given dent mark preventing properties in the form of a yield strength of at least 1000 MPa at a temperature of approximately 20° C. by means of the thermo-mechanical deformation process and possibly a yield strength increasing heat treatment. |
