| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gear excellent in pitching resistance and a manufacturing method therefor. <P>SOLUTION: The gear is subjected to carburizing treatment in a vacuum after being processed to a gear shape by forging or machining, subjected to nitriding treatment between in-furnace cooling after the carburizing treatment in a furnace and heating/holding prior to hardening when hardening is done after cooling in the furnace, and subjected to tempering treatment after the hardening. The gear, which is excellent in pitching resistance, has a component composition containing, by mass%, 0.15-0.35% C, 0.70-2.50% Si, 0.20-1.00% Mn, 0.01-0.80% Ni, 0.10-1.50% Cr, 0.01-0.80% Mo, and 0.005-0.200% Al, the balance being Fe and inevitable impurities. The Si and Cr in the component composition and the tempering softening resistance parameter H<SB POS="POST">SiCrN</SB>by the surface layer maximum invasion nitrogen amount by the nitriding treatment satisfy formula (1). Formula (1): H<SB POS="POST">SiCrN</SB>(=58Si+42×(Ns-Cr×14/52))≥80, where Si and Cr represent their amount contained (mass%), and Ns represents the surface layer maximum invasion nitrogen amount (mass%). <P>COPYRIGHT: (C)2013,JPO&INPIT |
