Preparation method of high-strength and high-toughness cold-working die steel billet

The invention provides a preparation method of a high-strength and high-toughness cold work die steel billet, and relates to the field of cold work die steel production, and the method comprises the following steps: VD furnace tapping, ladle turret treatment, tundish treatment, crystallizer treatment, secondary cooling, withdrawal and straightening machine treatment, flame cutting and square billet sizing. The total length of the crystallizer is 1500mm, the width and the height h1 of the crystallizer are 170mm, the radius r1 of four round corners of the crystallizer is 60mm, and the side length h2 of the crystallizer is 50mm; the temperature of tundish molten steel is 1480-1500 DEG C, the pulling speed is 0.6-0.8 m/min, and the water quantity of a crystallizer of a continuous casting machine is 140-160 m < 3 >/h. By adopting the designed key technology and process, the problem that oversized eutectic carbide is locally formed due to component segregation in the solidification process of the Cr8Mo2SiV steel gr