| 摘要 |
PURPOSE:To increase wear resistance and crack resistance, and to enhance durability of the seat for a poppet valve as a whole, by molding an annular seat part of powdery sintered alloy having a specified chemical constitution, a hardness, and a mechanical property of Charpy impact test value without a notch. CONSTITUTION:The seat part of a poppet valve is provided with an annular seat part 1, which has a fixing surface 1b to the body of the poppet valve and the seat surface 1a which contacts with a valve seat. In this case, the annular seat part 1 is composed of powdery sintered alloy having a chemical constitution of Co-Cr-W-C system, and a hardness of HV580-750, and also has a value 0.8- 1.7kg.m/cm of mechanical property of Charpy impact test without a notch. With such an arrangement, hard and not easily broken annular seat part 1 can be obtained, so that the poppet valve superior in durability can be obtained. |
