Niobium microalloyed light high-strength steel prepared by adopting warm rolling processing mode

The invention discloses niobium microalloyed light-weight high-strength steel prepared in a warm rolling processing mode, and the niobium microalloyed light-weight high-strength steel is a low-density warm-rolled steel plate comprising the following chemical components in percentage by mass: 0.20-0.32% of C, 0.20-0.40% of Si, 5.3-6.5% of Mn, less than or equal to 0.015% of P, less than or equal to 0.006% of S, 3.3-4.2% of Als, 0.010-0.035% of Nb, 0.0010-0.0035% of B, less than or equal to 0.006% of N, less than or equal to 0.006% of P, less than or equal to 0.015% of S, less than or equal to 0.015% of S, less than or equal to 0.015% of P, less than or equal to 0.015% of S, less than and the balance of Fe and inevitable impurities. The preparation method of the niobium microalloyed light high-strength steel comprises a smelting process, a hot rolling process, a warm rolling process and a heat treatment process. The niobium microalloyed light-weight high-strength steel provided by the invention is relatively go