Process for forging and molding special-shaped steel tube with a boss on excircle

The invention relates to a process for forging and molding a special-shaped steel tube with a boss on the excircle. The process comprises the following steps: preparing a tube blank is prepared; and on a horizontal hydraulic press, inserting a mandrel in the heated tube blank so as to mold the inner hole of the special-shaped steel tube with the boss on the excircle, and sequentially pressing against the tube blank by a plurality of special-shaped die rings so as to form the boss on the excircle of the steel tube, wherein each die ring is composed of an embedded sub-die ring and a die ring sleeve which are combined, and the inner wall of the embedded sub-die ring is provided with a groove corresponding to the boss of the tube blank. According to the invention, through adopting a die forging and open die forging combined flange forging molding mode, the overall continuity of the metal fiber of the special-shaped steel tube is ensured, and the overall strength requirement of the special-shaped steel tube is sat