OIL WELL STEEL PIPE EXCELLENT IN CRUSHING RESISTANCE CHARACTERISTICS AFTER PIPE EXPANSION

Title:

OIL WELL STEEL PIPE EXCELLENT IN CRUSHING RESISTANCE CHARACTERISTICS AFTER PIPE EXPANSION

Document Type and Number:

WIPO Patent Application WO/2004/001076

Kind Code:

A1

Abstract:

A method for producing an oil well steel pipe excellent in crushing resistance characteristics after pipe expansion, which comprises subjecting a steel piece having a specific chemical composition, wherein the contents of C, Mn, P, S, Nb, Ti, Al and N are values of specific ranges, respectively, and the balance is constituted by iron and inevitable impurities, to a hot rolling, winding up the resulting steel belt at a temperature of 300°C or lower, and forming the steel belt into a cylindrical shape with no further processing, or which comprises heating a steel piece having a specific chemical composition, wherein the contents of C, Mn, P, S, Nb, Ti, Al and N are values of specific ranges, respectively, and the balance is constituted by iron and inevitable impurities, to a temperature from A_C3 [°C] to 1150°C, and then cooling the resultant steel piece at a rate of 5 to 50°C/sec for the range of 400 to 800°C; and an oil well steel pipe produced by the method. The oil well steel pipe is reduced in the decrease of crushing strength by pipe expansion and is capable of having a recovered crushing strength by a low temperature aging at about 100°C.

Inventors:

ASAHI HITOSHI (JP)
TSURU EIJI (JP)

Application Number:

PCT/JP2003/007503

Publication Date:

December 31, 2003

Filing Date:

June 12, 2003

Export Citation:

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Assignee:

NIPPON STEEL CORP (JP)
ASAHI HITOSHI (JP)
TSURU EIJI (JP)

International Classes:

B21C37/08; C22C38/02; C22C38/04; C22C38/12; C22C38/14; C21D8/10; (IPC1-7): C21D28/10; C22C38/00

Foreign References:

JP2002129283A	2002-05-09
JPS6425916A	1989-01-27
JPS61279623A	1986-12-10
GB2155950A	1985-10-02

Other References: