STEEL PRODUCT FOR OIL WELL HAVING HIGH STRENGTH AND BEING EXCELLENT IN RESISTANCE TO SULFIDE STRESS CRACKING

Title:

STEEL PRODUCT FOR OIL WELL HAVING HIGH STRENGTH AND BEING EXCELLENT IN RESISTANCE TO SULFIDE STRESS CRACKING

Document Type and Number:

WIPO Patent Application WO/2000/068450

Kind Code:

A1

Abstract:

A steel product for an oil well which contains 0.10 to 0.40 % of C, 0.5 % or less of Si, 0.5 % or less of Mn, 0.0150 % or less of P, 0.0050 % or less of S, 0.5 to 2.5 % of Mo, 0.005 to 0.1 % of Al, 0.005 to 0.1 % of Ti, 0.01 to 0.1 % of Nb, 0.01 % or less of N, 0.0005 to 0.0050 % of B, with the proviso that the content of Ti is 3.4 times that of N or more, wherein the relationship between the yield strength (YS) thereof in terms of ksi and the Mo content thereof satisfies the formula (1), $g(a) = Mo-0.15YS $m(G) -18.9 and the balance between the contents of C and Mn and Mo satisfies the formula (2): $g(b) = 2.7 C + Mn + 2Mo $m(G) 2.0. The steel product is excellent in high strength and in resistance to SSC. A steel product for an oil well which further contains one or more of 0.2 % or less of Cr, 0.5 % or less of W, 0.01 to 0.3 % of V, 0.001 to 0.01 % of Zr, 0.001 to 0.01 % of Ca, 0.001 to 0.01 % of Mg, and 0.001 to 0.01 % of REM, in addition to the above, and has a yield strength of 120 ksi or more is also disclosed.

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Inventors:

SAKAMOTO SHUNJI (JP)
ASAHI HITOSHI (JP)

Application Number:

PCT/JP2000/002917

Publication Date:

November 16, 2000

Filing Date:

May 02, 2000

Export Citation:

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Assignee:

NIPPON STEEL CORP (JP)
SAKAMOTO SHUNJI (JP)
ASAHI HITOSHI (JP)

International Classes:

C21D1/18; C22C38/00; C22C38/06; C22C38/12; C22C38/14; (IPC1-7): C22C38/00; C21D6/00; C22C38/14; C22C38/32

Foreign References:

JP6104849B2	2017-03-29
JPH05271772A	1993-10-19
JPH0967624A	1997-03-11
JPH06116635A	1994-04-26
JPH11335731A	1999-12-07
JPS634043A	1988-01-09

Other References: