Title:
HOT-ROLLED HIGH-STRENGTH STEEL SHEET AND PROCESS FOR PRODUCTION THEREOF
Document Type and Number:
WIPO Patent Application WO/2011/152328
Kind Code:
A1
Abstract:
Disclosed are: a hot-rolled high-strength steel sheet which has excellent bake curability and stretch flageability and also has a tensile strength of 590 MPa or more; and a process for producing the steel sheet. The steel sheet has a chemical composition comprising, in mass%, 0.040-0.10% of C, 0.3% or less of Si, 1.7-2.5% of Mn, 0.030% or less of P, 0.005% or less of S, 0.1% or less of Al and 0.006-0.025% of N. In the structure of the steel sheet, the occupancy of a bainite phase is 60% or more and the total occupancy of a ferrite phase and a pearlite phase is 10% or less. In the steel sheet, cementite particles are precipitated at a density of 1.4 × 104 particles/mm2 or more in grains of the bainite phase, wherein the cementite particles have an average particle diameter of 1.5 μm or less.
Inventors:
KOHSAKA, Noriaki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
▲高▼坂 典晃 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
SETO, Kazuhiro (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
瀬戸 一洋 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
▲高▼坂 典晃 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
SETO, Kazuhiro (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
瀬戸 一洋 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
Application Number:
JP2011/062306
Publication Date:
December 08, 2011
Filing Date:
May 23, 2011
Export Citation:
Assignee:
JFE STEEL CORPORATION (2-3 Uchisaiwai-cho 2-chome, Chiyoda-ku Tokyo, 11, 〒1000011, JP)
JFEスチール株式会社 (〒11 東京都千代田区内幸町二丁目２番３号 Tokyo, 〒1000011, JP)
KOHSAKA, Noriaki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
▲高▼坂 典晃 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
SETO, Kazuhiro (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
JFEスチール株式会社 (〒11 東京都千代田区内幸町二丁目２番３号 Tokyo, 〒1000011, JP)
KOHSAKA, Noriaki (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
▲高▼坂 典晃 (〒11 東京都千代田区内幸町二丁目２番３号JFEスチール株式会社知的財産部内 Tokyo, 〒1000011, JP)
SETO, Kazuhiro (JFE STEEL CORPORATION 2-3, Uchisaiwai-cho 2-chome, Chiyoda-k, Tokyo 11, 〒1000011, JP)
International Classes:
C22C38/00; B21B3/00; C21D9/46; C22C38/06; C22C38/58
Attorney, Agent or Firm:
OCHIAI, Kenichiro (JFE TECHNO-RESEARCH CORPORATION 7th floor, Yanagiya building, 1-10, Nihonbashi 2-chome, Chuo-k, Tokyo 27, 〒1030027, JP)
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Claims: