Thin-gauge hot-rolled 1400 MPa steel and preparation method thereof

The invention relates to thin-gauge hot-rolled 1400 MPa steel which comprises the following chemical components in percentage by mass: 0.18 to 0.30 percent of C, less than or equal to 0.05 percent of Si, 2.0 to 3.0 percent of Mn, 0.02 to 0.35 percent of Al, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent of S, 0.01 to 0.10 percent of Nb, 0.010 to 0.030 percent of Ti, 0.5 to 1.0 percent of Cr, 0.01 to 0.10 percent of V, 0.10 to 0.30 percent of Mo, less than or equal to 0.004 percent of N, 0.0010 to 0.0040 percent of B and the balance of Fe and inevitable impurities. Through chemical component design, a C-Si-Mn-Nb-Ti-Cr-Mo-V-B component system is adopted, the hardenability of the material is improved by adding a proper amount of Mo and B elements, a martensite structure is obtained, the strength of the material is guaranteed by means of solution strengthening of C, Mn and Cr and fine grain strengthening and structure strengthening of Nb, the yield strength of the obtained steel is