Title:
STEEL SHEET, MEMBER, METHODS FOR MANUFACTURING SAME, METHOD FOR MANUFACTURING HOT-ROLLED STEEL SHEET FOR COLD-ROLLED STEEL SHEET, AND METHOD FOR MANUFACTURING COLD-ROLLED STEEL SHEET
Document Type and Number:
WIPO Patent Application WO/2023/162190
Kind Code:
A1
Abstract:
Provided are: a steel sheet having a tensile strength (TS) of 780 MPa or more and having excellent collision characteristics; a member; and methods for manufacturing the steel sheet and the member. This steel sheet has a component composition having a carbon equivalent (CE) of 0.46% or more, and has a specific steel structure. In the steel sheet, the average crystalline particle size of ferrite is 25 μm or less, and variation coefficient (CV) of ferrite grain size × carbon equivalent (CE) equals 0.28 or less. When the steel sheet is bent by 90° in a rolling (L) direction by using the width (C) direction as an axis at curvature radius/sheet thickness of 4.2, and then bend restoration is performed on the steel sheet so as to be flat again, the ratio (NFvoid/NF) of ferrite grains having voids at interfaces with respect to all ferrite grains is 15% or less in an L cross-section in a 0-50 μm range from the steel sheet surface on the compression-tensile deformed side. The steel sheet has a tensile strength of 780 MPa or more.
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Inventors:
KOMINE SHINSUKE (JP)
NAKAGAITO TATSUYA (JP)
NAKAGAITO TATSUYA (JP)
Application Number:
PCT/JP2022/008145
Publication Date:
August 31, 2023
Filing Date:
February 28, 2022
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D9/46; C21D8/02; C22C38/00; C22C38/60
Domestic Patent References:
| WO2015151419A1 | 2015-10-08 | |||
| WO2018043456A1 | 2018-03-08 | |||
| WO2021140663A1 | 2021-07-15 | |||
| WO2016194272A1 | 2016-12-08 |
Foreign References:
| JP2020059881A | 2020-04-16 | |||
| JP2016028172A | 2016-02-25 | |||
| JP2010059452A | 2010-03-18 | |||
| JP2022510212A | 2022-01-26 | |||
| JP2011179050A | 2011-09-15 |
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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