CORROSION-RESISTANT STEEL FOR TUBING AND CASINGS Russian patent published in 2009 - IPC C22C38/26 F16L9/02 

FIELD: metallurgy.

SUBSTANCE: invention elates to metallurgy field, particularly to alloyed steel, provided for manufacturing of tubing and casing, and also downhole equipment, operating in hostile environment, containing hydrogen sulfide and carbonic acid. Steel contains carbon, silicon, manganese, chrome, molybdenum, vanadium, niobium, aluminium, rare-earth metals, iron and unavoidable admixtures, at following correlation of components, wt %: carbon not more than 0.16, silicon 0.30 - 0.50, manganese 0.50 - 0.70, chrome from more than 3.0 - 6.0, molybdenum 0.40 - 1.00, vanadium 0.04 - 0.10, niobium 0.04 - 0.10, aluminium 0,02 - 0.05, rare-earth metals 0.005 - 0.015, iron and unavoidable admixtures are the rest. In the capacity of unavoidable admixtures steel contains not more than 0.01 wt % of sulfur and not more than 0.01 wt % of phosphorus.

EFFECT: there are increased mechanical properties and stability to carbon dioxide corrosion, sulfide corrosive action under tension and biological corrosion.

2 cl, 4 tbl