Title:
STEEL SHEET AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2023/203815
Kind Code:
A1
Abstract:
The present invention provides a steel sheet which has a high strength, with TS ≥ 690 MPa, which achieves an excellent low-temperature toughness and low yield ratio, and which exhibits little acoustical anisotropy. The steel sheet has a component composition which contains prescribed elements in prescribed amounts, with the remainder being Fe and unavoidable impurities. The microstructure of the steel sheet at a position at a depth of 1/4 of the sheet thickness from the surface of the steel sheet in the sheet thickness direction has a ferrite fraction of 5-95% and an island-shape martensite fraction of 1-30%, with the remainder being tempered martensite and/or bainite. When crystal grains are defined as regions surrounded by a high angle grain boundary with an orientation difference of not less than 15 degrees, the average aspect ratio of the crystal grains is less than 2.0, and the number density of crystal grains which have an equivalent circle diameter of more than 30 μm is not more than 250/mm2.
Inventors:
SATO YUYA (JP)
TACHIBANA SHUNICHI (JP)
MURAKAMI YOSHIAKI (JP)
TACHIBANA SHUNICHI (JP)
MURAKAMI YOSHIAKI (JP)
Application Number:
PCT/JP2023/000107
Publication Date:
October 26, 2023
Filing Date:
January 05, 2023
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D8/02; C22C38/00; C22C38/08; C22C38/58
Foreign References:
| JP2019524987A | 2019-09-05 | |||
| JP2012017522A | 2012-01-26 | |||
| JP2019199649A | 2019-11-21 | |||
| JP2005226158A | 2005-08-25 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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