| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface coating cast omission pin without erosion by the melted aluminum and stands for long use and also excellent in breakage- proof by covering the surface of the pin with monolayer of one kind or bilayer of two or more kinds chosen from special group of nitride, carbon nitride, boron or boron nitride and making the surface roughness below the specified figure in R max. SOLUTION: The surface of the cast omission pin is covered with monolayer of one kind or bilayer of two or more kinds chosen from nitride, carbo nitride, boron or boron nitride which belongs to 4a, 5a or 6a group. Especially, in case of bilayer of two or more kinds, since the thermal fatigue cracks develop along with the border line of the layers, if the outside layer exfoliate the inside layer still remains and therefore the thermal fatigue cracks do not develop into the base metal and the pin can be used for longer period. The tool steel is suitable for the base metal of the cast omission pin because it is excellent in toughness. Also the surface roughness of the pin is 10μm in R max or below and therefore the generation of the thermal fatigue cracks are prevented.
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