| 摘要 |
PURPOSE:To obtain a bearing parts having a service life long and with a low dispersion even in contaminated oil by applying a carburizing quenching and a sub-zero treatment, etc., to a base stock for already worked bearing parts composed of the carburized steel and making this base stock into the prescribed surface hardness and surface residual austenitic quantity. CONSTITUTION:By working the carburized steel, the base stock for bearing parts having the prescribed shape is formed. After the carburized quenching treatment is applied to this base stock, preliminary tempering treatment (e.g. temp.: 110-130 deg.C, time: >=1hr) is applied. Successively, further, a sub-zero treatment (e.g. temp.: -50 to -80 deg.C, time: >=1hr) and main tempering treatment (e.g. temp.: 140-175 deg.C, time: >=2hr) are applied. Then, this base stock is made into 63-67RHrth surface hardness and 20-25% surface residual austenite quantity.
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