Seamless steel tubes and pipes for use in oil well

a technology of seamless steel and oil well, applied in the field of seamless steel tubes and pipes, can solve the problems of difficult to obtain stable mechanical strength and inability to realize stable mechanical strength, and achieve excellent mechanical strength. the effect of stability
US20060231168A1Inactive Publication Date: 2006-10-19SUMITOMO METAL IND LTD
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
SUMITOMO METAL IND LTD
Publication Date
2006-10-19
Estimated Expiration
Not applicable · inactive patent

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Abstract

Disclosed are seamless steel tubes for oil well use, comprising C: 0.14-0.35%, Si: 0.05-1.0%, Mn: 0.05-2.0%, Cr: 0.05-1.5%, Mo: 0.05-2.0%, Ti: 0-0.05%, V: 0-0.1%, and Al: not less than 0.010%, wherein the concentration product by Al and N content, corrected by Ti and V, is within the range of 0.00001 to 0.00050, and the residuals are Fe and impurities including P: 0.025% or less, and S: 0.010% or less. Ti, V, Nb, or B is preferably contained to enhance the quench hardenability as well as the resistance to sulfide stress corrosion cracking, and further Ca, Mg and / or REM is preferably contained to improve the shape of non-metallic inclusions, enhancing the resistance to sulfide stress corrosion cracking. Thus, said tubes by the invention can be produced by efficient means realizing energy savings, and widely used as ones having excellent stability in mechanical strength.
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Description

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to seamless steel tubes and pipes (hereinafter, simply referred to as tube(s)) for use in oil well, more particularly, to tubes having less variation of tensile strength, i.e., excellent stability in mechanical strength.

[0003] 2. Description of the Related Art

[0004] Seamless steel tubes having higher reliability compared to welded tubes, are frequently used in hostile oil well environment and / or high temperature environment, so that the tubes having higher mechanical strength in association with stable strength, higher toughness and higher resistance to sour gas environment degradation are required.

[0005] For instance, in Japanese Patent Application Publication No. 2001-73086, seamless steel tubes containing V, Nb, Ti, Cr and Mo that are arranged to satisfy the relationship expressed by the preset equation to thereby suppress the formation of M23C6 type carbide, which are in general formed ...

Claims

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