STEEL SHEET HAVING EXCELLENT IMPACT VISCOSITY, PLASTICITY AND STRENGTH, AND METHOD OF ITS PRODUCTION Russian patent published in 2021 - IPC C21D8/02 C21D9/46 C22C38/58 C22C38/40 C22C38/18 

FIELD: metallurgy.

SUBSTANCE: invention relates to a method for manufacturing a hot-rolled and annealed steel sheet and can be used in the automotive industry. Disclosed is a method of manufacturing a cold-rolled steel sheet, including the following stages: casting steel containing, in wt. %: 0,1 ≤ C ≤ 0,4, 3,5 ≤ Mn ≤ 8,0, 0,1 ≤ Si ≤ 1,5, Al ≤ 3, Mo ≤ 0,5, Cr ≤ 1, Nb ≤ 0,1, Ti ≤ 0,1, V ≤ 0,2, B ≤ 0,004, 0,002 ≤ N ≤ 0,013, S ≤ 0,003, P ≤ 0,015, Fe and impurities - the rest, with the receipt of a steel billet, reheating the billet to the temperature T_{rep. heat.} ranging from 1150°C to 1300°C, hot rolling the billet at a temperature of 800°C to 1250°C, while the final rolling temperature T_FRT 800°C or higher, cooling the hot-rolled steel sheet to a temperature of T_reel. reeling in a roll 650°C or lower with a cooling rate Vc1 ranging from 1°C / s to 150°C / s, winding a sheet into a roll at a temperature T_reel. reeling, then continuous annealing and cooling the hot-rolled steel sheet to room temperature; and performing cold rolling of the hot-rolled and annealed steel sheet with a cold rolling reduction ratio of 30% to 70%.

EFFECT: sheet is characterized by improved cold rollability and toughness, as well as high strength and ductility values.

27 cl, 5 tbl, 48 ex