Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Toyota Jidosha Kabushiki Kaisha

Yoshinobu Omiya

Yoichi Mukai

Masaaki Miura

Shinji Kozuma

Yutaka Suzuki

Hiroki Nakajima

Yukihiro Utsumi

Tetsuo Soshiroda

Yoshiki Tanaka

Yoshirou Tomioka

Takaaki Tamura

Tomohiro Kase

Manabu Kamura

Kouichi Makii

Shinichirou Nakamura

Shinji c/o Kobe Corporate Research Laboratories Kozuma

A cold rolled steel sheet satisfying on the basis of percent by mass the chemical composition of 0.06-0.6% C, 0.1-2% Si, 0.01-3% Al, 1-4% Si+Al, 1-6% Mn, Si/Mn&#x2266;0.40, in which there exists 10 or more pieces/100 &#x3bc;mof Mn&#x2014;Si composite oxide having Mn&#x2014;Si atom ratio (Mn/Si) of 0.5 or over and major axis of from 0.01 &#x3bc;m to 5 &#x3bc;m and also having a covering ratio of 10% or below at which the surface of the steel sheet is covered with oxide containing Si as the main component.

High-strength cold-rolled steel sheet excellent in coating adhesion, workability and hydrogen embrittlement resistance, and steel component for automobile

A high-strength cold-rolled steel sheet is disclosed that comprises a steel including C: 0.05 to 0.13 mass %, Si: 0.5 to 2.5 mass %, and Mn: 0.5 to 3.5 mass %, as well as Mo: 0.05 to 0.6 mass % and/or Cr: 0.05 to 1.0 mass %. The steel sheet is of composite structure of a ferrite+a second phase wherein the second phase has an area rate of 30 to 70% and is combined approximately in a shape of a network; a circle-equivalent average ferrite grain size is not more than 10 &#x3bc;m; and a circle-equivalent diameter of ferrite grain aggregate that exists continuously in an area surrounded by the second phase is not more than 3 times of the average ferrite grain size. The steel sheet has a high-strength and satisfies a balance of elongation and stretch flange formability (ratio of hole expansion) at a higher level.

High-strength cold-rolled steel sheet having outstanding elongation and superior stretch flange formability and method for production therof

Superhigh-strength dual-phase steel sheet of excellent fatigue characteristic in a spot welded joint

Hot-dip galvanized steel sheet and production thereof

Disclosed are alloying elements and microstructures suited for realizing a marked increase in strength of low-carbon or ultra-low-carbon steel plate using a high-density energy source such as a laser. Steel blanks satisfying both high formability and high strength requirements are provided which show sufficient press formability and yet can be markedly increased in strength by laser treatment or which have been markedly increased in strength by laser treatment in areas not to be subjected to severe forming.

Process of Producing high-formability steel plate with a great potential

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Kakogawa, Japan

Yoshinobu Omiya