Patent ID: 8580050

Claim:
A carburized machine part produced by processing a case hardening steel of the following alloy composition consisting of, by weight %, C: 0.1-0.3%, Si: 0.5-3.0%, Mn: 0.3-3.0%, P: up to 0.03%, S: up to 0.03%, Cu: 0.01-1.00%, Ni: 0.01-3.00%, Cr: 0.3-1.0%, one or more of Pb: 0.01-0.20%, Bi: 0.01-0.10%, and Ca: 0.0003-0.0100%, Mo: up to 2.0%, one or both of Nb: up to 0.20% and Ti: up to 0.20%, B: up to 0.01%, Al: up to 0.2%, N: up to 0.05%, balance of Fe and inevitable impurities, and satisfying the following condition: [Si %]+[Ni %]+[Cu %]-[Cr %]>0.5 to form a green and carburizing the green by vacuum carburization, wherein the content of carbon in edge-shaped surface portions of the carburized machine part is at least 0.6% and the content of carbon in planar surface portions of the carburized machine part is up to 1.1%.