Low-molybdenum high-strength steel and preparation method thereof

The invention relates to low-molybdenum high-strength steel and a preparation method thereof. According to the technical scheme, the method comprises the following steps: performing acid pickling treatment on hot-rolled steel plates, rolling the pickled steel plates according to 4-6 passes by adopting a cold rolling mill unit, rolling to 0.8-1.2mm, thereby obtaining cold-rolled steel sheet strips; heating the cold-rolled steel sheet strips to the temperature of 570-670 DEG C in a vacuum heating furnace at a heating speed of 20-30 DEG C per second, preserving the temperature for 20-40 minutes, cooling to the temperature of 200-230 DEG C at a cooling speed of 5-10 DEG C per second, and performing furnace cooling to room temperature. The hot-rolled steel plate comprises the following chemical components: 0.18-0.20wt% of C, 2.20-2.50wt% of Mn, 1.20-1.40wt% of Si, 0.08-0.12wt% of Mo, less than 0.01wt% of P, less than 0.003wt% of S, less than 0.004wt% of N and the balance of Fe and inevitable impurities; and the thickness of the hot-rolled steel plate is 3-5mm. The low-molybdenum high-strength steel disclosed by the invention has the characteristics of low production cost, simple process and short production period, and the strength and plasticity of the product are well matched.