To provide rolling and sliding parts excellent in dimensional stability and a manufacturing method therefor.
After applying carburizing-treatment to a material for parts already formed into a prescribed shape from a bearing steel, by heating at 840-870°C for ≥3 hr under carburizing atmosphere having ≥1.2% carbon potential, the carburized material is cooled to ≤830°C and successively, rapidly cooled. In this way, the total carbon content on the surface layer part from the surface to such depth that the maximum shearing stress acts is made to 1.0-1.6 wt% and solid-solution carbon content in a matrix on the surface layer part is made to 0.6-1.0 wt% and also, carbide is precipitated on the surface layer part and thus, the quantity of the carbide is made to 5-20% as the area ratio and the grain diameter of the carbide is made to ≤3μm. Further, the hardness at the deeper portion from the surface layer part is made to 30-64 Rockwell C hardness, and the amount of retained austenite at the deeper portion from the surface layer part is made to ≤15%.
MIKAMI TAKESHI
Einosuke Kishimoto
Akira Watanabe
Kiyosue Yasuko