Title:
HIGH TENSILE COLD-ROLLED STEEL SHEET AND PROCESS FOR PRODUCTION THEREOR
Document Type and Number:
WIPO Patent Application WO/2008/093815
Kind Code:
A1
Abstract:
A high tensile cold-rolled steel sheet which has a composition containing by
mass C: 0.001 to 0.05%, Si: 0.4% or below, Mn: 0.5 to 2.0%, P: 0.08% or below, S: 0.005%
or below, Al: 0.05% or below, and N: 0.0080 to 0.0250% with at least 0.0050% of solid-soluted
N at an N/Al ratio of 0.30 or above and an N/C ratio of 0.40 or above with the balance
being Fe and unavoidable impurities and a composite structure composed of 95.0
to 99.5% (in volume fraction) of ferrite phase and 0.5 to 5.0% (in volume fraction)
of a phase formed at low temperature and which exhibits a tensile strength of 340MPa
or above. The steel sheet does not contain a large amount of expensive alloying
elements and makes it possible to produce 340 to 440MPa grade high tensile cold-rolled
steel sheets which have yield ratios of 55% or below and are excellent in press
formability or hot-dip zinc-coated steel sheets easily at low costs even when
the cooling rate after annealing varies.
Inventors:
HANAZAWA KAZUHIRO (JP)
NAKAGAWA NOBUKO (JP)
FUJITA KOICHIRO (JP)
YASUHARA EIKO (JP)
NAKAGAWA NOBUKO (JP)
FUJITA KOICHIRO (JP)
YASUHARA EIKO (JP)
Application Number:
PCT/JP2008/051598
Publication Date:
August 07, 2008
Filing Date:
January 25, 2008
Export Citation:
Assignee:
JFE STEEL CORP (JP)
HANAZAWA KAZUHIRO (JP)
NAKAGAWA NOBUKO (JP)
FUJITA KOICHIRO (JP)
YASUHARA EIKO (JP)
HANAZAWA KAZUHIRO (JP)
NAKAGAWA NOBUKO (JP)
FUJITA KOICHIRO (JP)
YASUHARA EIKO (JP)
International Classes:
C22C38/00; B21B3/00; C21D9/46; C22C38/06; C22C38/60
Foreign References:
| JP2002053935A | 2002-02-19 | |||
| JP2002226937A | 2002-08-14 | |||
| JP2003328072A | 2003-11-19 | |||
| JP2001107186A | 2001-04-17 |
Attorney, Agent or Firm:
OCHIAI, Kenichiro (JFE TECHNO-RESEARCH CORPORATION7th Floor Yanagiya Building,1-10, Nihonbashi 2-chom, Chuo-ku Tokyo, JP)
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