Study on key problems on industrializations of semisolid rheologic forming processes

Semisolid rheologic forming process has become a new focus in the field of semisolid process because of its many obvious advantages such as shorter process route, smaller investment, lower cost and without reheating, compared with the thixotropic forming process. However, there are many key problems to be solved in its industrialization such as how to manufacture the semisolid slurry quickly, how to control and adjust the slurry quality efficiently, how to ration the slurry to pour into molds, how to design the mold and the forming process parameters etc. A product line of semisolid rheologic forging to produce steel castings used in rolling stocks has been constructed according to the research results. It is proved that a combination of several methods for manufacturing slurry, stirring and chemical grain refining, is a useful way to accelerate the slurry preparation and to control the slurry quality; that using a special pouring equipment with short and thick pouring nozzles and supplying an additional pressure are two available methods to pour successfully; that an automatic control system, especially the on line or real time concatenation control of the system is necessary in the rheologic forming process; that the mold material used in the rheologic forming process can be selected referring to the die-casting or the squeeze casting process; and that an actual and valuable way to increase the mold life is to form a special coating on the inner surface by the surface coating technology.