Patent ID: 8337089

Claim:
A mechanical component formed of steel containing at least 0.77 mass % and not more than 0.85 mass % of carbon, at least 0.01 mass % and not more than 0.25 mass % of silicon, at least 0.01 mass % and not more than 0.35 mass % of manganese, at least 0.01 mass % and not more than 0.15 mass % of nickel, at least 3.75 mass % and not more than 4.25 mass % of chromium, at least 4 mass % and not more than 4.5 mass % of molybdenum and at least 0.9 mass % and not more than 1.1 mass % of vanadium with a remainder consisting of iron and impurity, and having a surface, said surface being included in a region having a nitrogen enriched layer having a nitrogen concentration of at least 0.05 mass %, said nitrogen enriched layer having a carbon concentration and the nitrogen concentration, in total, of at least 0.82 mass % and not more than 1.9 mass % throughout all of the nitrogen enriched layer other than where carbides and nitrides are formed.