Title:
HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2020/080552
Kind Code:
A1
Abstract:
A hot-rolled steel sheet has a specified chemical composition, wherein, when the thickness of the steel sheet is defined as "t", a metallographic structure lying between a surface of the steel sheet and a depth t/4 from the surface in the steel sheet contains, in area fractions, 77.0 to 97.0% of bainite or tempered martensite, 0 to 5.0% of ferrite, 0 to 5.0% of pearlite, 3.0% or more of retained austenite, and 0 to 10.0% of martensite, the average crystal particle diameter in the metallographic structure excluding the retained austenite is 7.0 μm or less, the average number density of particles of iron-based carbides each having a diameter of 20 nm or more is 1.0×106 particles/mm2 or more, the tensile strength is 980 MPa or more, and the average Ni concentration in the surface is 7.0% or more.
Inventors:
YOKOI TATSUO (JP)
SHUTO HIROSHI (JP)
HAYASHIDA TERUKI (JP)
ANDO JUN (JP)
SAKAKIBARA MUTSUMI (JP)
SHUTO HIROSHI (JP)
HAYASHIDA TERUKI (JP)
ANDO JUN (JP)
SAKAKIBARA MUTSUMI (JP)
Application Number:
PCT/JP2019/041313
Publication Date:
April 23, 2020
Filing Date:
October 21, 2019
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
International Classes:
C21D9/46; C22C38/00; C22C38/58
Domestic Patent References:
| WO2014188966A1 | 2014-11-27 |
Foreign References:
| JPH06145894A | 1994-05-27 | |||
| JP2001073040A | 2001-03-21 | |||
| JP2006336074A | 2006-12-14 | |||
| JP2018197936A | 2018-12-13 | |||
| JP2005179703A | 2005-07-07 | |||
| JP2012251200A | 2012-12-20 | |||
| JP2015124410A | 2015-07-06 | |||
| JP2004218074A | 2004-08-05 | |||
| JP2008202149A | 2008-09-04 | |||
| JPS59219473A | 1984-12-10 |
Other References:
See also references of EP 3868904A4
Attorney, Agent or Firm:
TANAI Sumio et al. (JP)
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