METHOD OF PRODUCING HIGH-STRENGTH SHEET STEEL, CHARACTERIZED BY IMPROVED STRENGTH AND MOLDABILITY, AND OBTAINED HIGH-STRENGTH SHEET STEEL Russian patent published in 2020 - IPC C21D8/02 C21D9/46 C22C38/58 C23C2/06 

FIELD: metallurgy.

SUBSTANCE: method of producing sheet steel having a microstructure consisting of 71 to 91 % of total amount of martensite and bainite, from 9 to 13 % of residual austenite and, at most, 20 % of ferrite, includes production of cold-rolled sheet steel, wherein the chemical composition of steel contains the following, wt %: 0.13 % ≤ C ≤ 0.22 %; 1.2 % ≤ Si ≤ 2.3 %; 0.02 % ≤ Al ≤ 1.0 %; wherein 1.25 % ≤ Si + Al ≤ 2.35 %; 2.4 % ≤ Mn ≤ 3 %; Ti < 0.05 %; Nb < 0.05 %; wherein the residue is Fe and unavoidable impurities, sheet steel is annealed at the annealing temperature TA so as to obtain structure containing 80 to 100 % austenite and 0 to 20 % ferrite,—hardening of the sheet at cooling rate within range from 20 to 50 °S/s, up to quenching temperature QT in range from 240 to 310 °C,— sheet heating up to distribution temperature of PT in range from 400 to 465 °C and preservation of sheet at given temperature for period of time Pt in range from 50 to 250 s,—immediate sheet cooling down to room temperature.

EFFECT: method of producing high-strength sheet steel characterized by improved strength and moldability and high-strength sheet steel are disclosed.

30 cl, 4 tbl