HIGH STRENGTH HOT ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME

WIPO Patent Application WO/2014/171057

A1

Provided are: a high strength hot rolled steel sheet having a tensile strength of 980 MPa or more and excellent bending workability; and a method for producing the high strength hot rolled steel sheet. This high strength hot rolled steel sheet has a composition that contains more than 0.1% but 0.2% or less of C, from 0.5% to 3.0% (inclusive) of Si, from 1.0% to 3.5% (inclusive) of Mn, 0.05% or less of P, 0.004% or less of S, 0.10% or less of Al, 0.008% or less of N, from 0.05% to 0.15% (inclusive) of Ti and more than 0.10% but 0.30% or less of V with the balance made up of Fe and unavoidable impurities. This high strength hot rolled steel sheet is composed of surface layer regions having a structure wherein a ferrite phase forms the main phase and an inner region having a structure wherein a bainite phase forms the main phase. By setting the ratios of the surface layer regions in the thickness direction of the steel sheet to 1.0-5.0% (inclusive) of the total sheet thickness respectively from the front and back surfaces of the steel sheet, this high strength hot rolled steel sheet achieves a tensile strength (TS) of 980 MPa or more.

YAMAZAKI KAZUHIKO (JP)
NAKAJIMA KATSUMI (JP)
KAMI CHIKARA (JP)

PCT/JP2014/001380

October 23, 2014

March 11, 2014

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JFE STEEL CORP (JP)

B21B3/00; C22C38/00; C21D8/02; C21D9/46; C22C38/14; C22C38/58

JP2003321727A	2003-11-14
JP2007162076A	2007-06-28
JP2009057620A	2009-03-19
JP2010043323A	2010-02-25
JP2010095753A	2010-04-30
JP2011202192A	2011-10-13
JP2012062557A	2012-03-29
JP2012062558A	2012-03-29
JP2014025131A	2014-02-06
JP2012062558A	2012-03-29
JP2009270142A	2009-11-19

See also references of EP 2987886A4

KUMASAKA, Akira et al. (JP)
Akira Kumasaka (JP)

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