Micros truc ture and properties of vacuum counter-pres s ure cas t a luminum alloy

As a special casting process, counter-gravity casting has many advantages especially in producing thin-wall complicated castings and has widely been used in industry . In recent ten years, various different counter-gravity casting processes have been continuously developed such as vacuum suction casting, low-pressure casting and counter-pressure casting [2-4] et al. Vacuum counterpressure casting is a new kind of counter-gravity casting technology that was developed in recent years. It has all the advantages of vacuum suction casting, low-pressure casting and pressure chamber casting. Under vacuum counter-pressure condition it is considered that liquid melts fill mould cavity under the vacuum and crystallize under high pressure . Vacuum counter-pressure casting has many advantages and great potential in manufacturing complicated, large-size, thin-wall near net shape nonferrous alloy castings used for different industries such as aviation, airspace, defense, car and automobile industry fields, etc. In this paper equipment and technology of vacuum counter-pressure casting are briefly introduced. By comparison with gravity casting, microstructure and properties of aluminum alloy cast by vacuum counter-pressure casting were studied. 1 Experimental procedure