Method of carburizing a bearing steel to produce a roller member

摘要

Peeling occurring in a short period of time is avoided in a roller member such as a roller cam follower of a cam apparatus in a valve system of a car engine. The roller member is produced by heating an already processed a roller member material in a carburizing atmosphere of carbon potential being 1.2% or more at 840 to 870 DEG C for 3 hours or longer, thereby to carry out a carburization treatment, followed by quenching, said roller member material being formed in a predetermined shape from a bearing steel. Thereby, all amount of carbon are rendered to be 1.0 to 1.6 wt% in a surface portion of a range from a surface of a rolling face until a depth where a maximum shearing stress acts on, an amount of solute carbon is rendered to be 0.6 to 1.0 wt% in a matrix of said surface portion, and said surface portion is precipitated with carbides of 5 to 20% in an area rate and of particle size being 3 mu or less. IMAGE