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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 AC3 [°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 (C/O NIPPON STEEL CORPORATION Technical Development Bureau, 20-1 Shintom, Futtsu-shi Chiba, 293-8511, JP)
Tsuru, Eiji (C/O NIPPON STEEL CORPORATION Technical Development Bureau, 20-1 Shintom, Futtsu-shi Chiba, 293-8511, 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 CORPORATION (6-3 Otemachi 2-chome, Chiyoda-ku, Tokyo, 100-8071, JP)
Asahi, Hitoshi (C/O NIPPON STEEL CORPORATION Technical Development Bureau, 20-1 Shintom, Futtsu-shi Chiba, 293-8511, JP)
Tsuru, Eiji (C/O NIPPON STEEL CORPORATION Technical Development Bureau, 20-1 Shintom, Futtsu-shi Chiba, 293-8511, JP)
International Classes:
B21C37/08; C22C38/02; C22C38/04; C22C38/12; C22C38/14; C21D8/10; (IPC1-7): C21D28/10; C22C38/00
Foreign References:
JP2002129283A2002-05-09
JPS6425916A1989-01-27
JPS61279623A1986-12-10
GB2155950A1985-10-02
Other References:
See also references of EP 1516934A1
Attorney, Agent or Firm:
Aoki, Atsushi (A. AOKI, ISHIDA & ASSOCIATES Toranomon 37 Mori Bldg., 5-1, Toranomon 3-chom, Minato-ku Tokyo, 105-8423, JP)
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