Novel alloy plate meeting special comprehensive mechanical properties, and preparation method thereof

The invention discloses a preparation method of a novel alloy plate meeting special comprehensive mechanical properties. The transversal tensile strength and the longitudinal tensile strength are required to be not less than 320Mpa, the yield strength is required to be 230-270Mpa, the elongation is required to be not less than 14%, the Webster hardness is required to be 15-17, and cracks are avoided in the case of bending with a radius of 0.5mm. The preparation method comprises the following steps: proportioning, smelting and purifying according to component requirements; casting a flat ingotthrough a low-level semi-continuous casting method; homogenizing in a cast ingot heating furnace; rolling via 1+4 hot continuous rolling mill, and rolling to reach a thickness of 3.14mm via a single-stand cold rolling mill; then carrying out coiled material annealing to reach a completely-annealed state; then rolling via the single-stand cold rolling mill; annealing to achieve the required mechanical properties; and final