Koyo Seiko Company, Ltd.

Kawasaki Steel Corporation

Daido Tokushuko Kabushiki Kaisha

Daido Steel Co., Ltd.

Atsuhiko Ohta

Masao Goto

Kazuhiro Watanabe

Keniti Amano

Sadayuki Nakamura

Yutaka Kurebayashi

Masakazu Ikeda

Osamu Tsukamoto

Makoto Kamei

Tosiyuki Hosino

Satosi Yasumoto

Gorou Anan

Michiro Hamanoue

Yukinori Kanaike

Hiroshi Itoziri

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.

Steering rack comprising steel bar with rack teeth

Bearing material

Bearing component

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.

Steel composition for bearings and method of producing the same

Growing community of inventors

Kashiwara, Japan

Atsuhiko Ohta