Title:
STEEL SHEET AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2023/203702
Kind Code:
A1
Abstract:
Provided is a technique for achieving both of excellent toughness at a lower temperature and a low yield ratio in a high-strength steel having TS of equal to or larger than 690 MPa (TS ≥690MPa). Provided is a steel sheet having a component composition comprising 0.02% to 0.15% inclusive of C, 0.01% to 0.50% inclusive of Si, 0.05% to 2.50% inclusive of Mn, 0.5% or more and less than 5.0% of Ni, 0.03% or less of P, 0.005% or less of S, 0.0010% to 0.0080% inclusive of N, and a remainder comprising Fe and unavoidable impurities, in which the microstructure at a depth of 1/4 from the surface of the steel sheet when observed in the thickness direction has a ferrite fraction of 5 to 95%, an island martensite fraction of 1 to 30%, and a remaining part comprising tempered martensite and/or bainite, and the density of crystal grains each having a circle equivalent diameter of more than 30 μm, among all of crystal grains each defined as a region surrounded by a high angle grain boundary having an orientation difference of 15 degrees or more, is 200 grains/mm2 or less.
Inventors:
SATO YUYA (JP)
TACHIBANA SHUNICHI (JP)
MURAKAMI YOSHIAKI (JP)
TACHIBANA SHUNICHI (JP)
MURAKAMI YOSHIAKI (JP)
Application Number:
PCT/JP2022/018338
Publication Date:
October 26, 2023
Filing Date:
April 20, 2022
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D8/02; C22C38/08; C22C38/58
Domestic Patent References:
| WO2021106368A1 | 2021-06-03 | |||
| WO2000039352A2 | 2000-07-06 |
Foreign References:
| JP2013057105A | 2013-03-28 | |||
| JP2019119934A | 2019-07-22 | |||
| JP2019504200A | 2019-02-14 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
Download PDF:
Previous Patent: CONTROL DEVICE, VIDEO TRANSFER SYSTEM, CONTROL METHOD, AND PROGRAM
Next Patent: TERMINAL AND COMMUNICATION METHOD
Next Patent: TERMINAL AND COMMUNICATION METHOD