Title:
STEEL SHEET, AND PROCESS FOR PRODUCTION THEREOF
Document Type and Number:
WIPO Patent Application WO/2011/148490
Kind Code:
A1
Abstract:
Disclosed is a high-strength steel sheet in which ferrite crystal grains are finely divided to achieve static strength of 750 MPa or more and which has excellent dynamic deformation properties.
Specifically disclosed is a steel sheet having a chemical composition comprising 0.05 to 0.20% of C, 0.02 to 3.0% of Si, 0.5 to 3.0% of Mn, 0.5% or less of P, 0.05% or less of S, 0.05 to 1.0% of Cr, 0.01 to 1.0% of sol.Al, one or more elements selected from the group consisting of Ti, Nb, Mo, V and W in the total amount of 0.002 to 0.03%, and the remainder made up by Fe and impurities. The steel sheet has such a metallic structure that ferrite has an average crystal grain diameter of 3.0 μm or less in a region lying between the surface of the steel sheet and the depth of at least 100 to 200 μm in the thicknesswise direction of the steel sheet, the region is made up by ferrite at an areal ratio of 30 to 80% and the remainder structure, and the average spacing of the remainder structure in the thicknesswise direction is 3.0 μm or less. The steel sheet has such mechanical properties that the tensile strength is 750 MP or more, the product of the tensile strength and the breaking elongation is 13000 MPa·% or more, and the difference between the dynamic tensile strength at a tensile strain rate of 103/sec and static tensile strength at a tensile strain rate of 0.01/sec is 80 MPa or more.
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Inventors:
TANAKA Yasuaki (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
田中 泰明 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 住友金属工業株式会社内 Osaka, 〒5410041, JP)
TOMIDA Toshiro (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
田中 泰明 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 住友金属工業株式会社内 Osaka, 〒5410041, JP)
TOMIDA Toshiro (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
Application Number:
JP2010/059013
Publication Date:
December 01, 2011
Filing Date:
May 27, 2010
Export Citation:
Assignee:
SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
住友金属工業株式会社 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 Osaka, 〒5410041, JP)
TANAKA Yasuaki (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
田中 泰明 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 住友金属工業株式会社内 Osaka, 〒5410041, JP)
住友金属工業株式会社 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 Osaka, 〒5410041, JP)
TANAKA Yasuaki (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 〒5410041, JP)
田中 泰明 (〒41 大阪府大阪市中央区北浜４丁目５番３３号 住友金属工業株式会社内 Osaka, 〒5410041, JP)
International Classes:
C22C38/00; B21B1/26; B21B3/00; B21B45/02; C21D9/46; C22C38/60
Attorney, Agent or Firm:
HIROSE Shoichi (Tozan Building, 4-2 Nihonbashi Honcho 4-chome, Chuo-k, Tokyo 23, 〒1030023, JP)
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