STEEL PLATE FOR THICK STEEL PIPE, METHOD FOR MANUFACTURING SAME, AND HIGH STRENGTH THICK STEEL PIPE

Title:

STEEL PLATE FOR THICK STEEL PIPE, METHOD FOR MANUFACTURING SAME, AND HIGH STRENGTH THICK STEEL PIPE

Document Type and Number:

WIPO Patent Application WO/2014/156175

Kind Code:

A1

Abstract:

Provided are a steel plate for thick steel pipe having superior CTOD characteristics in parts thermally affected by circumferential welds, a manufacturing method for the same, and a thick steel pipe. A steel plate is formed from 0.03 - 0.10% C, 0.05 - 0.50% Si, 1.00 - 2.00% Mn, 0.015% or less P, 0.005% or less S, 0.20% or less (including 0%) Mo, 0.01 - 0.05% Nb, and if necessary, one or two or more of 0.005 - 0.1% Al, 1.00% or less Cu, 1.00% or less Ni, 0.50% or less Cr, and 0.05% or less V, Pcm* (%) (= C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/2 + V/10) ≤ 0.20, with the remainder being Fe and inevitable impurities. The bainite fraction of the parent material is 50% or greater and the island shaped martensite (MA) fraction in a two-phase reheated granular region is 5.0% or less. After a continuous cast slab of the component system above is reheated to a specific temperature, the same is hot rolled and thereafter undergoes accelerated cooling to 550 - 250°.

Inventors:

OHTA SHUSAKU (JP)
SHIMAMURA JUNJI (JP)
ISHIKAWA NOBUYUKI (JP)
ENDO SHIGERU (JP)
TSUYAMA SEISHI (JP)

Application Number:

PCT/JP2014/001801

Publication Date:

October 02, 2014

Filing Date:

March 27, 2014

Export Citation:

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Assignee:

JFE STEEL CORP (JP)

International Classes:

C22C38/00; B21C37/08; C21D8/00; C22C38/12; C22C38/58

Foreign References:

JP2012077325A	2012-04-19
JP2012077327A	2012-04-19
JP2013007101A	2013-01-10
JP2011132601A	2011-07-07
JPH05186823A	1993-07-27
JP2004263248A	2004-09-24
JPH0577740B2	1993-10-27

Other References: