METHOD FOR PRODUCING STEEL PARTS

摘要

Included are a reduced pressure carburization process wherein steel parts are subjected to a carburizing treatment in a carburizing gas under reduced pressure; a slow-cooling process wherein said steel parts which have been subjected to the reduced pressure carburization process are cooled slowly in a cooling gas; and a hardening process wherein prescribed regions of the cooled steel parts are heated using high density energy and then quenched. The steel parts subjected to the reduced pressure carburization process have a first part (where carbon diffuses readily) and a second part (where carbon diffuses with difficulty) wherein the diffusion rates of the carbon introduced during the carburizing treatment are different, depending on the shape, and the diffusion rate of the carbon introduced into the second part is slower than that in the first part. The reduced pressure carburization process is carried out under conditions such that the surface carbon concentration in the first part reaches a value within the range 0.65 ± 0.1 mass%.