PURPOSE: To produce bearing parts excellent in bending fatigue strength and rolling fatigue strength and good in machinability by working a case hardening steel having a specified compsn. to form into a prescribed shape, subjecting the same to carburizing treatment to regulate the concn. of C to specified one and executing finish working by specified carburizing abnormal layer thickness and residual austenite content.
CONSTITUTION: An alloy having a compsn. contg., by weight, 0.15 to 0.25% C, ≤0.1% Si, 0.2 to 0.8% Mn and 0.2 to 0.8% Cr, furthermore contg. 10Si+Mn+ Cr≤2.0%, 0.01 to 0.015% S, 0.4 to 0.6% Ni, 0.6 to 1.0% Mo, 0.01 to 0.05% Al, 0.02 to 0.05% Nb and 0.005 to 0.025% N, in which the content of P is regulated to ≤0.01% and that of O to ≤0.002%, and the balance substantial Fe is worked to form into a shape close to that of bearing parts. This stock is subjected to carburizing treatment to regulate the concn. of C in the surface layer part to 0.7 to 0.9%. The stock obtd. by the same in which the depth of the carburizing abnormal layer is regulated to ≤6μm and the content of residual austenite is regulated to 5 to 30% is subjected to required finish working.
NAKAMURA SADAYUKI
MIZUNO YOSHIKI
HONDA MOTOR CO LTD
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