SEAMLESS HOT-ROLLED STEEL PIPE AND METHOD OF ITS PRODUCTION Russian patent published in 2025 - IPC C21D8/10 C21D9/08 C22C38/42 C22C38/48 C22C38/50 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to the seamless hot-rolled steel pipes manufacturing, intended for operation in the hydrogen sulphide-containing environment, in particular, to production of oil and gas pipelines intended for transportation of oil or oil-containing material containing aggressive corrosive substances (hydrogen sulphide, carbon dioxide). Seamless pipe is made out of steel containing wt. %: carbon 0.05-0.10, silicon 0.18-0.27, manganese 0.70-1.00, copper not more than 0.25, nickel not more than 0.20, chrome 0.50-0.80, niobium 0.01-0.05, titanium 0.005-0.010, aluminium 0.01-0.03, nitrogen not more than 0.008, sulphur not more than 0.005, phosphorus not more than 0.010, balance is iron and unavoidable impurities. Pipe has bainite-ferrite structure with rack-type bainite, volume fraction of which is not less than 70 %. Length of not less than 80 % of bainitic strips grouped into stacks is not more than 15 mcm. Between bainite laths there are layers of residual austenite with volume fraction of not less than 1 %.

EFFECT: improving corrosion resistance and cold resistance of seamless hot-rolled pipes at providing the strength class of not lower than K52.

2 cl, 6 dwg, 2 tbl