Title:
HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT WORKABILITY, AND A METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2012/020847
Kind Code:
A1
Abstract:
Provided are high-strength hot-rolled steel sheet having excellent workability in which a hole expansion ratio (λ) of 125% or more can be reliably obtained and the TS is 490 MPa or more and less than 590 MPa, and a method for producing said high-strength hot-rolled steel sheet. A high-strength hot-rolled steel sheet having excellent workability and characterized by having: a composition containing, in mass %, 0.04 to 0.1% of C, 0.3 to 1.3% of Si, 0.8 to 1.8% of Mn, 0.3% or less of P, 0.005% or less of S, 0.005% or less of N, 0.005 to 0.1% of Al, at least one selected from among 0.002% or more and less than 0.03% of Ti, 0.002% or more and less than 0.03% of V, and 0.002% or more and less than 0.02% of Nb, and the remainder being Fe and unavoidable impurities; and a microstructure in which, in relation to the entire structure, the area ratio of a ferrite phase is 85% or more, the area ratio of a bainite phase is 10% or less, the area ratio of phases other than the ferrite phase and the bainite phase is 5% or less, and the area ratio of an acicular ferrite phase in relation to the entire ferrite phase is 30% or more and less than 80%.
Inventors:
NAKAJIMA KATSUMI (JP)
MEGA TETSUYA (JP)
MIZUNO REIKO (JP)
MORIYASU NORIAKI (JP)
MEGA TETSUYA (JP)
MIZUNO REIKO (JP)
MORIYASU NORIAKI (JP)
Application Number:
PCT/JP2011/068494
Publication Date:
February 16, 2012
Filing Date:
August 09, 2011
Export Citation:
Assignee:
JFE STEEL CORP (JP)
NAKAJIMA KATSUMI (JP)
MEGA TETSUYA (JP)
MIZUNO REIKO (JP)
MORIYASU NORIAKI (JP)
NAKAJIMA KATSUMI (JP)
MEGA TETSUYA (JP)
MIZUNO REIKO (JP)
MORIYASU NORIAKI (JP)
International Classes:
C21D8/02; C22C38/14; C21D9/46
Domestic Patent References:
| WO2009028515A1 | 2009-03-05 |
Foreign References:
| JPH04276024A | 1992-10-01 | |||
| JPH1030149A | 1998-02-03 | |||
| JPH0711382A | 1995-01-13 | |||
| JPH08176723A | 1996-07-09 | |||
| JP2002539330A | 2002-11-19 | |||
| JP2001164322A | 2001-06-19 | |||
| JP2010189738A | 2010-09-02 | |||
| JPH11117039A | 1999-04-27 | |||
| JP2009052065A | 2009-03-12 |
Other References:
See also references of EP 2604716A4
Attorney, Agent or Firm:
OCHIAI, Kenichiro (JP)
Ken-ichiro Ochiai (JP)
Ken-ichiro Ochiai (JP)
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Claims:
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