PROCESS FOR PRODUCTION OF DUPLEX STAINLESS STEEL PIPE

Title:

PROCESS FOR PRODUCTION OF DUPLEX STAINLESS STEEL PIPE

Document Type and Number:

WIPO Patent Application WO/2010/082395

Kind Code:

A1

Abstract:

A process for the production of a duplex stainless steel pipe having a minimum yield strength of 758.3 to 965.2MPa, which comprises: subjecting a duplex stainless steel material having a chemical composition that contains by mass C: 0.03% or less, Si: 1% or less, Mn: 0.1 to 4%, Cr: 20 to 35%, Ni: 3 to 10%, Mo: 0 to 6%, W: 0 to 6%, Cu: 0 to 3%, N: 0.15 to 0.60% with the balance being Fe and impurities to hot working either alone or followed by solution treatment to produce a pipe stock for cold working; and then cold-rolling the pipe stock into a duplex stainless steel pipe, characterized in that the cold rolling is conducted under such conditions that the reduction ratio (Rd) (in terms of reduction in area) in the final cold rolling step falls within the range of 10 to 80% and satisfies the relationship (1): Rd=exp[{ln(MYS)-ln(14.5×Cr+48.3×Mo+20.7×W+6.9×N)}/0.195]∙∙∙(1) wherein Rd and MYS represent reduction ratio (%) (in terms of reduction in area) and desired yield strength (MPa) respectively; and Cr, Mo, W, and N represent their respective contents (mass%).

Inventors:

SUWABE HITOSHI (JP)
ONO TOSHIHIDE (JP)

Application Number:

PCT/JP2009/068743

Publication Date:

July 22, 2010

Filing Date:

November 02, 2009

Export Citation:

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Assignee:

SUMITOMO METAL IND (JP)
SUWABE HITOSHI (JP)
ONO TOSHIHIDE (JP)

International Classes:

C21D8/10; B21B21/00; B21C1/22; B21C23/08; C22C38/00; C22C38/58

Domestic Patent References:

WO2009014001A1

2009-01-29

Foreign References:

JPH02290920A	1990-11-30
JPH11302801A	1999-11-02
JPH02290920A	1990-11-30
JPH07207337A	1995-08-08
JPH05277611A	1993-10-26

Other References: