Economical high-aluminum and low-silicon TRIP steel for automobiles and preparation method of TRIP steel

The invention discloses economical high-aluminum and low-silicon TRIP high-strength steel for automobiles and a preparation method of the TRIP steel, and belongs to the technical field of production of high-strength steel for automobiles. The TRIP steel comprises the components of, by mass, 0.15-0.25% of C, 0.1-0.5% of Si, 1.5-3.0% of Al, 1.5-2.5% of Mn, 0.1-1.0% of Cu, 0.01% of P and Lt, 0.005% of S and Lt and the balance Fe. The preparation method comprises the following steps of smelting, pouring, forging, heat preservation, hot rolling, thatching, acid pickling, cold rolling and annealingtreatment. Micro-alloy elements contained in the steel are less, so that the steel is economical and beneficial for being recovered; Si is partially replaced by Al, the ductility is improved, and thegalvanization performance of a cold rolled steel plate is improved; a small quantity of Cu is added, the defect of Al at the aspect of strength is made up through solid solution and precipitation strengthening, and the extensi