METHOD FOR PRODUCING GEAR HAVING EXCELLENT TOOTH SURFACE STRENGTH AND GEAR HAVING EXCELLENT TOOTH SURFACE STRENGTH

摘要

PROBLEM TO BE SOLVED: To provide a gear having excellent tooth surface strength where pitting resistance and wear resistance in the tooth surface are further improved.;SOLUTION: The invention refers to a method for producing a gear using case hardening steel for machine structural use comprising, by weight, 0.3 to 3.0% Cr as the stock, and in which the content of C in the outermost surface is controlled to 0.5 to 0.9%, the content of N in the outermost surface is controlled to 0.3 to 0.8%, and the content of N is made equal to that of C, and further having a surface hardened structure where the intrusion depth of N reaches a depth of at least 80% of the effective hardening depth as a depth at which hardness Hv 550 can be obtained. In the method, the gear stock made of case hardening steel for machine structural use is subjected to nitriding treatment simultaneously with carburizing treatment at 800 to 950°C, and is thereafter cooled, thus the gear having excellent tooth surface strength with a surface hardened structure where not only C but also N is allowed to enter into solid solution can be obtained.;COPYRIGHT: (C)2006,JPO&NCIPI