STEEL OF HIGHER RUSTPROOF QUALITIES AND ELECTRIC-WELDED PIPES MADE THEREOF Russian patent published in 2019 - IPC C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular, to production of low carbon and low alloy steels of increased corrosion resistance for manufacture of electric-welded oil-field pipes. Steel contains components in the following ratio, wt. %: carbon 0.05–0.25, manganese 0.30–1.50, silicon 0.10–0.70, chromium 0.01–0.60, nickel 0.03–0.20, copper 0.06–0.20, phosphorus not more than 0.015, sulfur not more than 0.005, aluminum 0.01–0.06, calcium 0.0001–0.008, iron and inevitable impurities, including oxygen and magnesium – the rest. Steel has a banded ferritic-perlitic structure not higher than 2 points and contains non-metallic inclusions of complex composition, containing aluminum, calcium, magnesium and oxygen, and the total content of calcium and magnesium in the inclusions exceeds the aluminum content.

EFFECT: improved corrosion resistance of steel is ensured by providing the absence of local areas with reduced corrosion resistance, as well as improving the manufacturability and weldability of steel while maintaining strength, toughness and cold resistance.

2 cl, 3 tbl