Nissan Motor Company Limited

Kabushiki Kaisha Kobe Seiko Sho

Koyo Seiko Company, Ltd.

Masakazu Ikeda

Kazuhiro Watanabe

Keizo Otani

Jun Katoh

Takuro Yamaguchi

Toshiki Satou

Atsuhiko Ohta

Yukinori Kanaike

Osamu Tsukamoto

Satoshi Abe

Gorou Anan

Makoto Kamei

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

A high strength gear is provided which comprises a base metal of an iron-base alloy, the base metal being carburized or carbonitrided and having a tooth surface, and a coating containing Fe nitride and/or Fe carbonitride, formed on the tooth surface. A method of forming a high strength gear is also provided.

High strength gear and method of producing the same

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Kobe, Japan

Masakazu Ikeda