Title:
HIGH-STRENGTH HOT ROLLED STEEL SHEET HAVING TENSILE STRENGTH OF 780 MPa OR MORE
Document Type and Number:
WIPO Patent Application WO/2014/148001
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a high-strength hot rolled steel sheet with good formability, which has good magnetic characteristics and excellent punchability, while having a tensile strength of 780 MPa or more. A high-strength hot rolled steel sheet having a tensile strength of 780 MPa or more, which is characterized by having a component composition that contains, in mass%, 0.070-0.140% of C, 0.10-1.00% of Si, 1.00-1.80% of Mn, 0.050% or less of P, 0.0050% or less of S, 0.0080% or less of N, 0.010-0.100% of Al and 0.050-0.150% of Ti, with the balance made up of Fe and unavoidable impurities. This high-strength hot rolled steel sheet having a tensile strength of 780 MPa or more is also characterized in that: 95% by volume or more of a bainite structure is contained; 80% or more of carbides among all the carbide precipitates are dispersed at the grain boundaries of bainitic ferrite that constitutes the bainite structure; and 80% or more of all the carbide precipitates have an average particle diameter of 20-300 nm.
Inventors:
NAKAJIMA KATSUMI (JP)
FUNAKAWA YOSHIMASA (JP)
NAKAMURA NOBUYUKI (JP)
FUNAKAWA YOSHIMASA (JP)
NAKAMURA NOBUYUKI (JP)
Application Number:
PCT/JP2014/001379
Publication Date:
September 25, 2014
Filing Date:
March 11, 2014
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C22C38/14; C22C38/58; H01F1/16; C21D8/12; C21D9/46
Domestic Patent References:
| WO2012036307A1 | 2012-03-22 | |||
| WO2011152541A1 | 2011-12-08 | |||
| WO2009133965A1 | 2009-11-05 | |||
| WO2013115205A1 | 2013-08-08 |
Foreign References:
| JP2003268509A | 2003-09-25 | |||
| JPS63166931A | 1988-07-11 | |||
| JP4273768B2 | 2009-06-03 |
Other References:
See also references of EP 2977481A4
Attorney, Agent or Firm:
KUMASAKA, Akira et al. (JP)
Akira Kumasaka (JP)
Akira Kumasaka (JP)
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