| 摘要 |
PURPOSE:To obtain a tappet excellent for scuffing resistance and pitching resistance in the tappet used for an engine, by forming forming a slide surface part with a cam contained with a specific amount of cementite in area ratio and the foundation wth baitnite. CONSTITUTION:The foundation of pearlite in chilled construction of casting is applied with heat treatment to form baitnite. In this way, a difference of hardness between cementite and the foundation is decreased, and a fatigue crack generated in the vicinity of a boundary can be prevented. Further even if the crack is generated in the vicinity of the boundary, its propagation is prevented, and the cementite is preferably dissolved to an extent its wear resistance is not reduced, in consequence ratio of area occupied by the cementite is arranged to 25-40%. In this way, a tappet excellent for scuffing resistance and pitching resistance can be obtained. |
