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Title:
THICK-WALLED HIGH-STRENGTH SOUR-RESISTANT LINE PIPE AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2014/010150
Kind Code:
A1
Abstract:
Provided are a line pipe suitable as a thick-walled high-strength sour-resistant line pipe having a pipe thickness of 20 mm or greater and a tensile strength of 560 MPa or higher, and a method for producing the line pipe. In this line pipe, the base material part comprises: specific amounts of C, Si, Mn, P, S, Al, Nb, Ca, N, and O; one or more types of Cu, Ni, Cr, Mo, V, and Ti as (an) optional component(s); and Fe and inevitable impurities as the remainder. In this line pipe : the microstructure in the pipe-thickness direction comprises 90% or more bainite in the region from a depth of 2 mm from the inner surface to a depth of 2 mm from the outer surface; the hardness in regions except for the center segregation part is 220 Hv10 or less and the hardness in the center segregation part is 250 Hv10 or less in terms of hardness distribution in the pipe-thickness direction; and the major axis of air bubbles, inclusions, and inclusion clusters existing in the region from a depth of 1 mm from the inner surface to a position where the depth is 3/16 of the pipe thickness and in the region from a depth of 1 mm from the outer surface to a position where the depth is 13/16 of the pipe thickness in the pipe-thickness direction is 1.5 mm or shorter. A CC slab having the aforementioned composition is hot-rolled under specific conditions and is then subjected to accelerated cooling.

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Inventors:
TANIZAWA AKIHIKO (JP)
NAKAMICHI HARUO (JP)
KAWANAKA TORU (JP)
UCHITOMI NORIAKI (JP)
OZEKI TAKAFUMI (JP)
Application Number:
PCT/JP2013/002160
Publication Date:
January 16, 2014
Filing Date:
March 29, 2013
Export Citation:
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Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; B21C37/08; C21D8/02; C22C38/12; C22C38/50; G01N29/04
Foreign References:
JP2009133005A2009-06-18
JPH07136748A1995-05-30
JP2012046789A2012-03-08
JP2011132600A2011-07-07
JP2012077331A2012-04-19
US20120121453A12012-05-17
JP2009221534A2009-10-01
JP2010077492A2010-04-08
JP2009133005A2009-06-18
JPH06220577A1994-08-09
JP2003013175A2003-01-15
JP2010209461A2010-09-24
JP2011063840A2011-03-31
JP2010209460A2010-09-24
JP2006063351A2006-03-09
JP2011001607A2011-01-06
JP2010189722A2010-09-02
JPH108196A1998-01-13
JP2009120899A2009-06-04
JP2010189720A2010-09-02
JPH09324216A1997-12-16
JPH09324217A1997-12-16
JP2003226922A2003-08-15
JP2004003014A2004-01-08
JP2004003015A2004-01-08
JP2005060820A2005-03-10
JP2005060837A2005-03-10
JP2008056962A2008-03-13
JP2008101242A2008-05-01
JP2009052137A2009-03-12
JP2000160245A2000-06-13
Other References:
See also references of EP 2871252A4
Attorney, Agent or Firm:
KUMASAKA, Akira et al. (JP)
Akira Kumasaka (JP)
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