Method for producing boron-containing non-quenching and tempering plastic mold steel

A production method of a boracic non-hardened and tempered plastic die steel belongs to the technical field of medium steel plate production. The process is that a continuous casting billet is soaked at the temperature of 1150-1250 DEG C; the hot rolling temperature is controlled, the start rolling temperature of the finish rolling is 900-950 DEG C, and the finishing rolling temperature is 840-880 DEG C; the steel plate is in controlled cooling after the hot rolling, and the cooling speed is controlled at 1-5 DEG C per second; and tempering treatment is required after rolling. The methods of controlled rolling and controlled cooling are adopted to obtain the 20-80mm bainite structure steel plate, stress relief tempering is carried out after rolling, and the combination property of the steel plate meets the process requirements of P20 pre-hardened steel. The yield strength of the steel plate is not less than 650MPa, the tensile strength is not less than 900MPa, the hardness of the cross section is 280-330HV, a