Kawasaki Steel Corporation

Jfe Steel Corporation

Tohru Hayashi

Keniti Amano

Mitsuhiro Okatsu

Fumimaru Kawabata

Yasuhiro Omori

Takashi Iwamoto

Hiroki Ota

Kazukuni Hase

Tomoya Koseki

Toshiyuki Hoshino

Noritsugu Itakura

Toshio Fujita

Kenji Oi

Takaaki Toyooka

Akihiro Matsuzaki

We provide a steel product that includes, by mass %, C: 0.35-0.7%, Si: 0.30-1.1%, Mn: 0.2-2.0%, Al: 0.005-0.25%, Ti: 0.005-0.1%, Mo: 0.05-0.6%, B: 0.0003-0.006%, S: 0.06% or less, P: 0.02% or less, Cr: 0.2% or less, and the balance Fe and inevitable impurities, and has a structure of bainite and/or martensite, the total volume fraction of bainite and martensite being 10% or more, and an induction hardened member that is made of the steel product having a hardened surface layer formed by induction hardening and has a prior austenite grain size of 12 &#x3bc;m or less through the layer thickness. The member has high fatigue strength and therefore is suitable for an automobile drive shaft, an automobile constant velocity joint or the like.

Steel product for induction hardening, induction-hardened member using the same, and methods producing them

High-strength and high-toughness non heat-treated steel having excellent

A method of manufacturing a thick steel product of high strength and high toughness having excellent weldability with minimal variation of material properties, comprises heating a steel raw material to the temperature of Ac.sub.3 to 1350.degree. C., hot rolling and then cooling at the cooling rate of 10.degree. C./sec. or less. The steel raw material has the following composition:

Method of manufacturing thick steel product of high strength and high

This invention provides bainite steel materials having a less scattering of properties in a thickness direction or between steel materials by using a chemical composition of C: not less than 0.001 wt % but less than 0.030 wt %, Si: not more than 0.60 wt %, Mn: 1.00-3.00 wt %, Nb: 0.005-0.20 wt %, B: 0.0003-0.0050 wt % and Al: not more than 0.100 wt % and rendering not less than 90% of the material into a bainite texture in steel materials such as thick steel plates, steel sheets, section steels, rod steels and the like.

Bainitic steel materials having a less scattering of properties and

Method of producing bainitic steel materials having a less scattering of

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Kurashiki, Japan

Tohru Hayashi