Cold-rolled dual-phase steel plate with 1,200 MPa-level tensile strength and preparation method thereof

The invention belongs to the field of a metal material, which relates to low-alloy advanced high-strength steel (AHSS), in particular to a cold-rolled dual-phase steel plate with 1,200 MPa-level tensile strength and a preparation method thereof. The cold-rolled dual-phase steel plate is characterized by comprising the following chemical components in percentage by mass: 0.19-0.21% of C, 0.70-0.90% of Si, 1.90-2.10% of Mn, 0.01-0.02% of Cr, 0.02-0.04% of Nb, less than 0.005% of P, less than 0.003% of S and the balance of Fe and unavoidable impurities. The preparation method comprises the following steps: smelting according to the chemical components, casting blank and forging the blank to obtain a slab; and performing conventional hot rolling, acid pickling and cold rolling on the slab; and particularly, the preparation method further comprises a continuous annealing technique, wherein the heating rate is 10 DEG C/s, the annealing temperature is between 820 and 860 DEG C, the heat preservation time is between