Abstract: A bearing steel having long rolling life comprising, by weight, 0.65 to 0.90% of C, 0.15 to 0.50% of Si, 0.15 to 1.0% of Mn and 2.0 to 5.0% of Cr, and the balance of Fe. Austenite grain size can be prevented from becoming coarser to make hardening in high temperature possible by further adding one or more of 0.0090 to 0.0200% of N, 0.010 to 0.050% of Al and 0.005 to 0.500% of Nb as optional elements to the steel. Further, rolling fatigue life can be improved by further adding one or more of 0.20 to 0.50% of Ni, 0.10 to 2.00% Of Mo and 0.05 to 1.00% of V as optional elements, and machinability can be improved by further adding one or more of 0.02 to 0.05% of S, 0.005 to 0.10% of rare earth elements, 0.02 to 0.30% of Pb, 0.0005 to 0.0100% of Ca, 0.001 to 0.200% of Bi, 0.005 to 0.20% of Se and 0.005 to 0.100% of Te in the steel as optional elements.

Abstract: A free-cutting steel having a high fatigue strength which consists essentially of 0.30-0.50% C, 0.10-0.50% Si, 0.50-1.00% Mn, 0.04-0.12% S, 0.005-0.20% V, 0.005-0.018% Al, 0.05-0.30% Pb, and 0.001-0.006% Ca by weight, and as the remainder, Fe and inevitable impurities. It may additionally contain 0.50% or less of Cr.

Abstract: A case hardened steel having small oxygen, sulfur, and phosphorous contents and consisting essentially of, by weight, 0.10-0.30% carbon, not more than 0.50% silicon, not more than 1.50% manganese, not more than 0.012% phosphorous, not more than 0.009% sulfur, 0.02-0.04% aluminum, not more than 0.0010% oxygen, and 0.01-0.02% nitrogen, and a member or members selected from the group consisting of 0.20-1.50% chromium, 0.10-0.35% molybdenum, and 0.20-3.0% nickel, the remainder being iron together with impurities, and and a method of manufacturing the same.