METHOD FOR PRODUCING HIGH-STRENGTH COLD-ROLLED CONTINUOUSLY ANNEALED FLAT STOCK OF IF-STEEL Russian patent published in 2021 - IPC C21D1/26 C21D8/04 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to methods for producing high-strength cold-rolled continuously annealed flat stock of IF-steels, usable in the automobile industry. A method for producing high-strength cold-rolled and annealed stock, including smelting of steel, continuous casting into slabs, hot rolling of the ingot, cold rolling of the resulting stock, and recrystallisation annealing. Steel is smelted, containing, % wt.: C - 0.003 to 0.007, Si - 0.01 to 0.02, Mn - 0.35 to 0.55, P - 0.03 to 0.05, Al - 0.02 to 0.06, Ti - 0.03 to 0.05, Nb - 0.03 to 0.05, Fe and unavoidable impurities the rest, hot rolling is finished at a temperature of 840 to 920°C, recrystallisation annealing of the steel stock is performed at a temperature set depending on the strength class numerically equal to the minimum permissible yield strength of 180 MPa, 220 MPa and 260 MPa in accordance with the dependence: wherein K is a coefficient, numerically equal to the minimum permissible yield strength of 180 MPa, 220 MPa and 260 MPa, 920 and 0.5 are empirical coefficients, overaging is executed after recrystallisation annealing at a temperature of 420-460°C for steel stock with a minimum permissible yield strength of 180 MPa or at a temperature of 360-400°C for steel stock with a minimum permissible yield strength of 220 MPa and 260 MPa.

EFFECT: expansion of the technological capabilities of the method for producing high-strength cold-rolled stock is ensured while maintaining high values of ductility and stampability.

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