SUPER-STRENGTH MULTI-PHASE STEEL AND METHOD FOR MAKING STEEL STRIP OF MULTI-PHASE STEEL Russian patent published in 2021 - IPC C21D8/02 C21D1/32 C21D9/46 C21D9/56 C22C38/40 C22C38/58 C23C2/40 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to the manufacture of a steel strip from multiphase steel. Disclosed is a method of manufacturing a steel strip from multiphase steel with a minimum tensile strength of 980 MPa in an unhardened state which contains, wt%: C - 0.075-0.115, Si - 0.400-0.500, Mn - 1.900-2.350, Cr - 0.250-0.400, Al - 0.010-0.060, N - 0.0020-0.0120, P - 0.020, S - 0.0020, Ti - 0.005 -0.060, Nb - 0.005-0.060, V - 0.005-0.020, B - 0.0005-0.0010, Mo - 0.200-0.300, Ca 0.0010-0.0060, Cu - 0.050, Ni - 0.050, Sn - 0.040, H - 0.0010, the rest is iron and impurities. The method includes the production of strip workpieces by preliminary rolling, selection of the slab thickness and a certain but variable thickness of the strip workpiece, hot rolling of the strip workpiece with a reduction rate of 72-87%, winding a hot-rolled strip at the temperature of the beginning of bainite formation, cold rolling a hot-rolled strip to obtain a cold-rolled strip with the required final thickness, heating a cold-rolled strip with continuous annealing to a temperature of 700-950 ° C, cooling an annealed steel strip moose. The cooling is carried out to intermediate temperatures with different cooling rates. It is possible to obtain various thicknesses of cold-rolled strip from a strip billet of variable thickness supplied to hot rolling.

EFFECT: invention makes the process of production of a steel strip more effective.

11 cl, 4 ex, 17 dwg