400 Mpa-grade high-strength hot rolled steel and production method thereof

The invention discloses 400 Mpa-grade high-strength hot rolled steel and a production method thereof. The hot rolled steel is prepared from the following chemical components in percentage by weight: 0.22%-0.25% of C, 1.20%-1.30% of Mn, 0.20%-0.40% of Si, 0.023%-0.028% of V, 0.030% or less than 0.030% of S, 0.035% or less than 0.035% of P, 0.013%-0.020% of N and the balance of Fe and inevitable impurities. The hot rolled steel has the characteristics of high strength, high plasticity, high toughness and the like, and the cost is lower. According to the method, converter blowing and nitrogen blowing throughout tapping are adopted in the smelting process, nitrogen bottom blowing and ferrovanadium nitride microalloying are adopted in the refining process, non-protective operation is adopted throughout continuous casting, and accordingly, the N content in molten steel is increased to ensure the content of V and N in the product. Nitrogen bottom blowing is adopted throughout refining, high-strength hot rolled steel