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Title:
COLD-ROLLED STEEL SHEET AND HOT-DIP GALVANIZED COLD-ROLLED STEEL SHEET
Document Type and Number:
WIPO Patent Application WO/2018/179386
Kind Code:
A1
Abstract:
A cold-rolled steel sheet with a tensile strength of at least 980 MPa has a prescribed chemical composition. The microstructure, in area%, is ferrite: 1-29%, retained austenite: 5-20%, martensite: less than 10%, pearlite: less than 5%, and balance: bainite and/or tempered martensite. The total length of interfaces, where ferrite is in contact with martensite or with retained austenite having an equivalent circular radius of at least 1 µm, is 100 µm or less per 1000 µm2. Said cold-rolled steel sheet has excellent workability and low-temperature toughness, especially low-temperature toughness after introducing plastic deformation.

Inventors:
YOKOYAMA TAKAFUMI (JP)
OKAMOTO RIKI (JP)
YAMAGUCHI YUJI (JP)
SHIOKAWA KAZUKI (JP)
NAKAHIRA YUICHI (JP)
KAWATA HIROYUKI (JP)
Application Number:
PCT/JP2017/013736
Publication Date:
October 04, 2018
Filing Date:
March 31, 2017
Export Citation:
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Assignee:
NIPPON STEEL & SUMITOMO METAL CORP (JP)
International Classes:
C22C38/00; C23C2/06; C21D9/46
Domestic Patent References:
WO2017002883A12017-01-05
WO2013047830A12013-04-04
WO2013151238A12013-10-10
Foreign References:
JP2014034716A2014-02-24
JP2009108343A2009-05-21
JP2004068050A2004-03-04
JP2006104532A2006-04-20
JP2007262494A2007-10-11
JP2015086468A2015-05-07
JP2015200006A2015-11-12
JP2014034716A2014-02-24
JP2011132602A2011-07-07
JP2015025208A2015-02-05
JP2014133944A2014-07-24
Other References:
See also references of EP 3604582A4
Attorney, Agent or Firm:
BRIGHTAS IP ATTORNEYS (JP)
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