METHOD FOR THE PRODUCTION OF COLD-RESISTANT ROLLED STEEL SHEET Russian patent published in 2023 - IPC C21D8/02 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: production of sheet metal in thicknesses up to 50 mm from cold-resistant steel for use in heavy engineering, in building structures at low temperatures up to -70°C. A method for producing cold-resistant steel sheet includes making a steel billet, austenizing it, deforming it by rough and finish rolling, and cooling. The billet is obtained from steel containing, wt.%: carbon 0.04-0.20, silicon 0.1-0.5, manganese 0.9-1.9, sulfur - NMT 0.009, phosphorus - NMT 0.015, chromium - NMT 0.5, nickel - NMT 0.4, copper - NMT 0.4, aluminum - 0.02-0.07, vanadium - 0.002-0.10, niobium - 0.01-0,10, titanium - 0.003-0.10, molybdenum - 0.05-0.5, nitrogen - NMT 0.010, calcium - NMT 0.005, boron - NMT 0.005, arsenic - NMT 0.08, zirconium - NMT 0.2, iron and inevitable impurities - the rest. Austenization by heating the billet for rolling is carried out to a temperature of 1150-1300°C, start finishing rolling at a temperature of 880-990°C, and finish at a temperature of 810-920°C, then the resulting steel sheet is cooled in air to ambient temperature, then it is heat treated, at which it is heated to a temperature of 900-950°C, accelerated cooling with water up to a temperature of NMT 350°C, reheating to 500-690°C and subsequent cooling in air.

EFFECT: high mechanical properties, including at -70°C.

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