Bainite non-quenched and tempered steel and preparation method thereof

The invention belongs to the technical field of automobile steel, and relates to bainite non-quenched and tempered steel and a preparation method thereof. The bainite non-quenched and tempered steel comprises the following components in percentage by mass: 0.22 to 0.29 percent of C, 0.25 to 0.40 percent of Si, 1.80 to 2.00 percent of Mn, 0.40 to 0.60 percent of Cr, 0.01 to 0.08 percent of V, less than or equal to 0.015 percent of P, 0.020 to 0.050 percent of S, 0.020 to 0.050 percent of Ti, 0.020 to 0.040 percent of Zr, more than or equal to 0.010 percent of Al, 0.010 to 0.020 percent of N, less than or equal to 15 ppm of [O], less than or equal to 2 ppm of [H] and the balance of Fe and inevitable impurities. In the production process, through reasonable component design, controlled rolling and controlled cooling process and pit-entering slow cooling temperature design, the steel has excellent obdurability. The design of low carbon, high manganese and trace V, Ti and Zr is adopted, the effects of solid soluti