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Title:
HIGH STRENGTH WELDED STEEL PIPE FOR LOW TEMPERATURE USE HAVING SUPERIOR BUCKLING RESISTANCE, AND METHOD FOR PRODUCING THE SAME, AND METHOD FOR PRODUCING STEEL SHEET FOR HIGH STRENGTH WELDED STEEL PIPE FOR LOW TEMPERATURE USE HAVING SUPERIOR BUCKLING RESISTANCE
Document Type and Number:
Japanese Patent JP2013204103
Kind Code:
A
Abstract:

To provide a high strength steel pipe of API X100 grade, superior in buckling resistance and toughness at low temperatures after coating treatment, a method for producing the high strength steel pipe, and a method for producing a steel sheet serving as a base material.

In a steel pipe, a base material includes, by mass%, more than 0.03% and 0.08% or less of C, 0.01-0.5% of Si, 1.5-3.0% of Mn, 0.01-0.08% of P, S and Al, 0.005-0.025% of Nb, 0.005-0.025% of Ti, 0.001-0.010% of N, 0.005% or less of O, and one or two or more of Cu, Ni, Cr, Mo, V and B, with 0.19≤PCM≤0.25 and the remainder being Fe and inevitable impurities, has a TS of 760-930 MPa, a uniform elongation of 5% or more and a YR of 85% or less; the micro structure of the base material mainly comprises bainite including island martensite, and includes 1-10% of a lower part bainite and 3% or less of residual austenite; seam welding by submerged arc welding is performed at a heat-input of 80 kJ/cm or less; and seam welding metal has a specified component composition.


Inventors:
SHIMAMURA JUNJI
NISHIMURA KIMIHIRO
OKATSU MITSUHIRO
Application Number:
JP2012075384A
Publication Date:
October 07, 2013
Filing Date:
March 29, 2012
Export Citation:
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Assignee:
JFE STEEL CORP
International Classes:
C22C38/00; B21C37/08; B23K9/025; B23K9/23; B23K31/00; B23K35/30; C21D7/12; C21D8/02; C22C38/58; B23K103/04
Domestic Patent References:
JP2009057629A2009-03-19
JP2007314828A2007-12-06
JP2010202976A2010-09-16
Attorney, Agent or Firm:
Shigeru Inoue
Kazuhiro Mori