ULTRAHIGH-STRENGTH MULTIPHASE STEEL WITH IMPROVED PROPERTIES DURING PRODUCTION AND PROCESSING Russian patent published in 2017 - IPC C22C38/38 C22C38/54 C21D9/46 C23C2/06 C21D1/26 

FIELD: metallurgy.

SUBSTANCE: invention relates ultrahigh-strength multiphase steel having a particular composition, as well as to production a cold- or hot-rolled steel strip, wherein required multiphase microstructure is generated during continuous annealing. For uniform distribution of mechanical properties of strip, having different cross section and thickness, cold- or hot-rolled strip is heated to temperature of 700–950 °C, then heated steel strip is cooled at a rate of 15–100 °C/s from annealing temperature to first intermediate temperature of 300 °C to 500 °C, then steel strip is cooled at a rate of 15–100 °C/s to a second intermediate temperature of 200 °C to 250 °C; then steel strip undergoes cooling in air at a rate of 2 to 30°C/s to ambient temperature or is cooled at a rate of 15–100 °C/s from first intermediate temperature to ambient temperature.

EFFECT: obtaining maximum strength of steel.

15 cl, 6 dwg