Title:
HIGH STRENGTH STEEL SHEET, PRODUCTION METHOD THEREFOR, AND HIGH STRENGTH GALVANIZED STEEL SHEET
Document Type and Number:
WIPO Patent Application WO/2018/092735
Kind Code:
A1
Abstract:
Provided is a high strength steel sheet that has a composition range including 0.001-0.200% of Ti and/or 0.001-0.200% of Nb among other components and has a steel structure wherein ferrite is present at an area ratio of 20% or more, the ferrite having an average crystalline grain size of 10-20 µm, bainite is present at an area ratio of 5% or more, martensite is present at an area ratio of 5% or more, the total area ratio of bainite and martensite is 15% or more, and residual austenite is present at a volume ratio of 5% or more. The high strength steel sheet has a TS of 780 MPa or more which is achieved by a texture of ferrite formed as a micro structure having an inverse intensity ratio of γ-fibers to α-fibers of more than 3.0, and has excellent ductibility and stiffness as well as deep drawability.
Inventors:
MINAMI HIDEKAZU (JP)
KAWASAKI YOSHIYASU (JP)
KANEKO SHINJIRO (JP)
KAWASAKI YOSHIYASU (JP)
KANEKO SHINJIRO (JP)
Application Number:
PCT/JP2017/040814
Publication Date:
May 24, 2018
Filing Date:
November 13, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D9/46; C22C38/14; C22C38/60; C22C18/00
Domestic Patent References:
WO2016125463A1 | 2016-08-11 | |||
WO2013047836A1 | 2013-04-04 |
Foreign References:
JP2015145518A | 2015-08-13 | |||
JP2008024980A | 2008-02-07 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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