CORROSION-RESISTANT STEEL FOR SEAMLESS HOT-ROLLED TUBING AND CASING PIPES HIGH OPERATIONAL RELIABILITY AND PIPE MADE THEREFROM Russian patent published in 2016 - IPC C22C38/46 F16L9/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, specifically to corrosion-resistant steels for production of seamless hot-rolled tubing and casing pipes operating under conditions of high concentration of carbon dioxide and hydrogen sulphide in composition of pumped hydrocarbon medium at deposits, located in Arctic areas. Steel contains following component ratio, wt%: carbon 0.14-0.23, silicon 0.17-0.4, manganese 0.4-0.7, chromium more than 1.0-5.1, molybdenum 0.15-0.5, vanadium 0.04-0.06, nickel 0.1-0.7, copper 0.15-0.5, aluminium 0.02-0.05, sulphur not more than 0.007, phosphorus not more than 0.015, nitrogen not more than 0.014, iron - balance. Coefficient of operational reliability of steel, defined by expression R=0.8×[Cr]+3.5×[Mo]+2.5×[Cu], is 2.0÷5.5, and content of sulphur must not be over S_max=0.01-0.01×[Cu], wt%.

EFFECT: improved operational reliability of pipes due to increased resistance to carbon-dioxide corrosion while maintaining resistance to sulphide corrosion, high cold resistance and prevention of hot brittleness during hot rolling of steel pipes.

3 cl, 4 tbl