Kobe Steel, Ltd.

Sei Kimura

Koichi Sakamoto

Tomoko Sugimura

Yosuke Shindo

Atsuhiko Yoshida

Tetsushi Deura

Takeshi Inoue

Hiroshi Yaguchi

Takehiro Tsuchida

Tsuyoshi Mimura

Masaki Shimamoto

Masaki Kaizuka

Masato Kaiso

Masami Somekawa

Akihiro Owaki

Ikuo Hoshikawa

High cleanliness spring steel useful in manufacturing a spring with SiO-based inclusions being extremely controlled and excellent in fatigue properties is provided. High cleanliness spring steel which is steel containing;

High cleanliness spring steel and high cleanliness spring excellent in fatigue properties

A bearing steel material which contains 0.8-1.1 mass % C, 0.15-0.8 mass % Si, 0.1-1.0 mass % Mn, 1.3-1.8 mass % Cr, up to 0.05 mass % P (0 mass % is excluded), up to 0.015 mass % S (0 mass % excluded), 0.0002-0.005 mass % Al, 0.0002-0.0020 mass % Ca, 0.0005-0.010 mass % Ti, up to 0.0080 mass % N (0 mass % is excluded), and up to 0.0025 mass % O (0 mass % is excluded). The steel material contains oxide inclusions which have an average composition that comprises, in terms of mass %, 20-50% CaO, 20-50% AlO, 20-70% SiO, and 3-10% TiO.

Bearing steel material with excellent rolling fatigue property and bearing part

A steel wire rod is obtained, in which a gas flow rate during gas stirring in molten steel treatment is controlled to be 0.0005 Nm/min to 0.004 Nm/min per molten steel of 1 ton, thereby the rod satisfies a specified composition, and oxide base inclusions in any section including an axis line of the steel wire rod satisfy the following composition X, the inclusions having width of 2 &#x3bc;m or more perpendicular to a rolling direction, wherein the number of the oxide base inclusions of the following composition A is 1 to 20, and the number of the oxide base inclusions of the following composition B is less than 1: In the steel wire rod, drawability and fatigue properties are improved to the utmost.

Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same

High cleanliness spring steel useful in manufacturing a spring with SiO-based inclusions being extremely controlled and excellent in fatigue properties is provided.

A machine structure steel superior in chip disposability and mechanical properties which contains sulfide-type inclusions such that those particles of sulfide-type inclusions with major axes not shorter than 5 &mgr;m have an average aspect ratio not larger than 5.2 and which also contains coarse particles of sulfide-type inclusions such that the relation a/b&lE;0.25 is satisfied, where a denotes the number of particles of sulfide-type inclusions with major axes not shorter than 20 &mgr;m, and b denotes the number of particles of sulfide-type inclusions with major axes not shorter than 5 &mgr;m. The machine structure steel exhibits good chip disposability and mechanical properties despite its freedom from lead.

Machine structure steel superior in chip disposability and mechanical properties and its method of making

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Kakogawa, Japan

Sei Kimura