METHOD OF MANUFACTURING CORROSION ROLLED PRODUCT FROM LOW-ALLOY STEEL Russian patent published in 2019 - IPC C21D8/02 C21D9/46 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, in particular to the production of heat-treated sheet metal from strip steels, intended for the manufacture of electric-welded oil and gas pipelines and oil-field pipes used at low temperatures for the transportation of corrosive media. To increase the cold resistance and corrosion resistance of rolled sheet with a thickness of 10–30 mm, a slab of steel is produced containing, wt. %: carbon 0.10–0.20, manganese 0.5–1.0, silicon 0.01–0.40, chromium 0.05–0.40, nickel 0.05–0.40, copper 0.05–0.40, niobium 0.01–0.08, phosphorus not more than 0.020, sulfur not more than 0.006, aluminum 0.01–0.06, iron and unavoidable impurities – the rest, rough rolling is carried out to an intermediate thickness, then finish rolling is carried out at a rolling end temperature equal to Ar₃+(20÷80) °C followed by air cooling, rolled sheet is heated to Ac₃+(10÷50) °C with a shutter speed of 2h min/mm, where h is the thickness of rolled metal, followed by accelerated cooling at 15÷70 °C/s to a temperature of not more than 40 °C, then the rental is reheated to a temperature of 700÷750 °C with an exposure of (1.0÷4.5)h, this provides a fine ferritic-bainite structure with a ferrite grain score of not larger than 9 and a ferritic streakiness of 0 points and has a purity in corrosive nonmetallic inclusions not more than 2 inclusions per 1 mm².

EFFECT: increased cold resistance and corrosion resistance.

1 cl, 3 tbl