Abstract: A steel for use in high strength pinion shaft which is not refined and used by applying high frequency hardening, with less occurrence of peeling during hobbing, having high surface hardness, impact value and torsional strength after high frequency hardening, and with less heat treatment strains during high frequency hardening, containing, on the mass % basis; C: 0.45-0.55%, Si: 0.10-0.50%, Mn: 0.50-1.20%, P: 0.025% or less, S: 0.025% or less, Mo: 0.15-0.25%, B: 0.0005-0.005%, Ti: 0.005-0.10%, and N: 0.015% or less, satisfying: 0.80?Ceq 0.95 and f value?1.0, and the balance of Fe and inevitable impurities, as well as a manufacturing method thereof.

Abstract: A steel bar for a steering rack that contains 0.50 to 0.60% by mass of C, 0.05 to 0.5% by mass of Si, 0.2 to 1.5% by mass of Mn, 0.0005 to 0.003% by mass of B, 0.005 to 0.05% by mass of Ti, 0.0005 to 0.1% by mass of Al, and 0.002 to 0.02% by mass of N is provided. Given D as a diameter of the steel bar, then the steel bar is adjusted in such a manner that quenched and tempered structures in a portion of the steel bar at a depth of D/4 from a surface satisfy conditions I), II), and III) as follows: I) a sum of a tempered bainitic structure and a tempered martensitic structure accounts for 30 to 100% in area percentage; II) a regenerated perlite structure accounts for 0 to 50% in area percentage; and III) a sum of the tempered bainitic structure, the tempered martensitic structure, and the regenerated perlite structure accounts for 50 to 100% in area percentage.

Abstract: A steel bar for a steering rack that contains 0.50 to 0.60% by mass of C, 0.05 to 0.5% by mass of Si, 0.2 to 1.5% by mass of Mn, 0.0005 to 0.003% by mass of B, 0.005 to 0.05% by mass of Ti, 0.0005 to 0.1% by mass of Al, and 0.002 to 0.02% by mass of N is provided. Given D as a diameter of the steel bar, then the steel bar is adjusted in such a manner that quenched and tempered structures in a portion of the steel bar at a depth of D/4 from a surface satisfy conditions I), II), and III) as follows: I) a sum of a tempered bainitic structure and a tempered martensitic structure accounts for 30 to 100% in area percentage; II) a regenerated perlite structure accounts for 0 to 50% in area percentage; and III) a sum of the tempered bainitic structure, the tempered martensitic structure, and the regenerated perlite structure accounts for 50 to 100% in area percentage.

Abstract: A steel for use in high strength pinion shaft which is not refined and used by applying high frequency hardening with less occurrence of peeling during hobbing, having high surface hardness, impact value and torsional strength after high frequency hardening, and with less heat treatment strains during high frequency hardening, containing, on the mass % basis; C; 0.45-0.55%, Si: 0.10-0.50%, MA: 0.50-1.20%, P: 0.025% or less, S: 0.025% or less, Mo: 0.15-0.25%, B: 0.0005-0.005%, Ti: 0.005-0.10%, and N: 0.015% or less, satisfying; 0.80≦Ceq 0.95 and f value≦1.0, and the balance of Fe and inevitable impurities, as well as a manufacturing method thereof.

Abstract: Bearing materials used for rolling bearings, such as roller bearings and ball bearings, and in particular, a bearing material having an extended rolling contact fatigue life.A bearing material having an extended rolling contact fatigue life comprises: 0.95 to 1.10 mass % of C, 0.15 to 0.70 mass % of Si, 1.15 mass % or less of Mn, 0.90 to 1.60 mass % of Cr and 0.025 mass % or less of P, and further 0.025 mass % or less of S and 0.0012 mass % or less of O as elements forming nonmetal inclusions, and the balance being Fe and incidental impurities, and the bearing material further contains 0.020 mass % or less of AlN, or the number of nonmetal sulfide inclusions each having a thickness of 1 .mu.m or more is 1,200 or less in an observation area of 320 mm.sup.2 for further extending the rolling contact fatigue life.

Abstract: A bearing component for use in anti-friction bearings as a bearing ring or rolling member is made from a steel comprising 0.6 to 0.8 wt. % of C, 0.05 to 0.25 wt. % of Si, 0.2 to 0.9 wt. % of Mn, 0.4 to 1.2 wt. % of Cr, one or both of 0.10 to 0.30 wt. % of Mo and 0.03 to 0.10 wt. % of V, and the balance Fe and inevitable impurities. The steel as hardened and tempered contains carbide having a maximum particle size of up to 1.5 .mu.m, and the amount of the carbide is 2 to 7% in area ratio. The steel therefore has improved cold workability, providing bearing components of a prolonged rolling fatigue life at a reduced cost.

Abstract: Bearing steel materials that are superior in cold workability, machinability, hardenability and rolling contact fatigue life are provided. During the processing of steel materials, the generation of large carbides, that detrimentally affect the rolling contact fatigue life of the steel, is inhibited, thereby obviating the necessity of a heat treatment for dissolving the carbides. The present steel material contains the following alloy elements in percentage by mass: 0.55% to 0.82% of carbon; 0.05% to 0.20% of silicon; 0.50% or less of manganese; 0.90% to 1.30% of chromium; 0.05% to 0.30% of molybdenum; and the remaining percentage substantially of iron. After the spheroidizing annealing of the steel material, the total cross-sectional area rate of carbide is 25% or less.