STEEL FOR OIL WELL PIPES WITH HIGH WET CARBON DIOXIDE GAS CORROSION RESISTANCE AND HIGH SEAWATER CORROSION RESISTANCE, AND SEAMLESS OIL WELL PIPE

摘要

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 said steel are provided. The steel consists of, by mass %, more than 0.10 % to 0.30 % of C, 0.10 % to 1.0 % of Si, 0.1 % to 3.0% of Mn, 2.0 % to 9.0 % of Cr and 0.01 % to 0.10% of Al and optionally 0.05 % to 0.5 % of Cu, and the balance of Fe and incidental impurities. P as the impurity is not more than 0.03 % and S as the impurity is not more than 0.01%. The steel has a substantially single martensite structure as quenched or as normalized condition, and not lower than 552 MPa yield strength as quenched-tempered or as normalized-tempered condition. IMAGE