Production method of large-diameter dual-phase steel tube blank

The invention relates to a production method of a large-diameter dual-phase steel tube blank. According to the main scheme, the method comprises a hollow electro slag ingot and hollow forging, and comprises the steps that an electrode blank used for hollow electro slag is produced, hollow electro slag remelting is conducted, hollow electro slag ingot air cooling is conducted, internal and externalsurfaces of the hollow electro slag remelting ingot are polished, the hollow electro slag ingot is heated, hollow forging is conducted, and air cooling is conducted after forging is conducted; the electrode blank used for the electro slag is an electrode blank formed by welding multiple minor sector electrode blanks which are connected in parallel, hollow electro slag remelting is conducted, after the hollow electro slag remelting ingot is heated, saddle forging is avoided, a mandril is directly penetrated for drawing out and forming, and then air cooling is conducted. According to the production scheme, the producti