Kobe Steel, Ltd.

Ikuo Hoshikawa

Koichi Sakamoto

Hiroshi Yaguchi

Takehiro Tsuchida

Yosuke Shindo

Masato Kaiso

Sei Kimura

Masami Somekawa

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

Ikuo Hoshikawa