METHOD FOR PRODUCTION OF HOT-ROLLED SHEETS FROM LOW-ALLOY STEEL FOR PRODUCTION OF CRITICAL METAL STRUCTURES Russian patent published in 2020 - IPC B21B1/38 C21D8/02 C22C38/58 C22C38/50 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used for production of thick sheets for metal structures of critical purpose, used in shipbuilding, fuel and energy complex, heavy engineering, including for structures operating at high (up to 250°C) temperatures. Method of producing hot-rolled sheets from low-alloyed steel for making critical metal structures involves an austenisation of continuously cast blanks, roughing, finishing rolling and cooling of sheets. Blanks are made from steel containing, wt.%: C 0.07-0.12; Si 0.16-0.35; Mn 1.25-1.75; Al 0.02-0.05; Ti 0.010-0.035; Mo 0.15-0.30; S not more than 0.006, P not more than 0.012, N not more than 0.009, Cr+Ni+Cu 0.35-0.7, V+Nb 0.05-0.16, Fe and unavoidable impurities. Coefficient of crack resistance at welding Pcm makes 0.23% or less, austenisation of continuously cast workpieces is carried out in the temperature range of 1180-1250°C, rough rolling is started at temperature not lower than 950°C and performed with relative reduction per pass of not less than 10% to thickness of 2-3.5 of thickness of finished sheet, finishing rolling is started at temperature of 750-800°C and finish at temperature of 750-820°C to obtain sheets with thickness of 16 to 70 mm, then, sheets with thickness of 16-40 mm are cooled or accelerated cooling of sheets with thickness of more than 40 to 70 mm with subsequent thermal treatment.

EFFECT: sheets with thickness of 16 to 70 mm are obtained for production of metal structures with guaranteed cold resistance at low temperatures to minus 60°C and high strength properties, preserved at high temperatures of operation, up to plus 250°C.

5 cl, 1 tbl, 2 ex