Patent ID: 8535457

Claim:
A rolling member constituted of steel containing at least 0.3 mass % and not more than 0.4 mass % of carbon, at least 0.3 mass % and not more than 0.7 mass % of silicon, at least 0.3 mass % and not more than 0.8 mass % of manganese, at least 0.5 mass % and not more than 1.2 mass % of nickel, at least 1.6 mass % and not more than 2.5 mass % of chromium, at least 0.1 mass % and not more than 0.7 mass % of molybdenum and at least 0.2 mass % and not more than 0.4 mass % of vanadium, and a balance of the steel is iron and impurities, in which the sum of the content of silicon and the content of manganese is not more than 1.0 mass %, the sum of the content of nickel and the content of chromium is at least 2.3 mass %, and the sum of the content of chromium, the content of molybdenum and the content of vanadium is not more than 3.0 mass %, wherein a hardened layer having a larger carbon content than an inner portion is formed on a region including the surface, the hardness of a surface layer portion of said hardened layer is at least 725 HV and not more than 800 HV, the maximum grain size of a carbide distributed in said surface layer portion is not more than 10 μm, the area ratio of said carbide on said surface layer portion is at least 7% and not more than 25%, and the hardness of said inner portion is at least 450 HV and not more than 650 HV.