Steel for oil well pipe with high corrosion resistance to wet carbon dioxide and seawater, and a seamless oil well pipe
AssigneeSumitomo Metal Industries, Ltd.
InventorsHideki Takabe, Masakatsu Ueda
Life of this patent
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Abstract
A steel for oil well pipe, which has excellent resistance to localized corrosion in CO2 environments and corrosion in seawater, and a seamless pipe made of the steel. The steel includes, in weight %, more than 0.10 to 0.30% C, 0.10 to 1.0% Si, 0.1 to 3.0% Mn, 2.0 to 9.0% Cr, 0.01 to 0.10% Al and optionally 0.05 to 0.5% Cu, and the balance including Fe and incidental impurities including not more than 0.03% P and not more than 0.01% S. The steel has a substantially single phase martensitic structure in the as-quenched or as-normalized condition, and yield strength of not lower than 552 MPa in the as-quenched-tempered or as-normalized-tempered condition.
Claims19
A steel having excellent resistance to wet CO2 corrosion and seawater corrosion comprising, in weight %, more than 0.10 to 0.30% C, 0.10 to 1.0% Si, 0.1 to 3.0% Mn, 2.5 to less than 7.0% Cr and 0.01 to 0.10% Al, the balance including Fe and incidental impurities including not more than 0.03% P and not more than 0.01% S, the steel having a microstructure in which 95% or more is martensite in an as-quenched or as-normalized condition, and a yield strength of not lower than 552 MPa in an as-quenched-tempered or normalized-tempered condition.
A steel having excellent resistance to wet CO2 corrosion and seawater corrosion comprising, in weight %, more than 0.10 to 0.30% C, 0.10 to 1.0% Si, 0.1 to 3.0% Mn, 2.5 to less than 7.0% Cr, 0.01 to 0.10% Al and 0.05 to 0.5% Cu, the balance including Fe and incidental impurities including not more than 0.03 % P and not more than 0.01% S, the steel having a microstructure in which 95% or more is martensite in an as-quenched or as-normalized condition, and a yield strength of not lower than 552 MPa in an as-quenched-tempered or normalized-tempered condition.
Dependencies are inferred from the claim text.