| 摘要 |
PROBLEM TO BE SOLVED: To provide rolling parts for an automobile transmission (gears, rolling elements of a non-stage transmission), having excellent rolling fatigue strength. SOLUTION: An alloy steel with a specific alloy composition is worked into a blank having a shape close to parts shape, subjected to carburizing or carbonitriding and quenching and to tempering, and then preformed into the shape and dimension determined by deducting the plating layer thickness from the final parts shape and dimension and adding the final finish working machining allowance after plating. The hardness of the surface of the resultant preformed part does not fall below Hv 700 even after heating treatment at <=300 deg.C for <=3 hr. Subsequently, NiP plating is applied to the preformed part and heat treatment is applied at <=300 deg.C for 3 hr to regulate the hardness of the NiP plating layer to >=Hv 800. Then, finish working is performed to obtain the final parts shape and dimension.
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