Single step centrifugal casting TiAl automotive valves

Centrifugal casting has been used to cast TiAl car valves. The casting has been carried out in vacuum using induction melting furnace coupled to a CaO crucible, which offers a maximum superheat of approximately 180 °C and much improved filling over normal cold wall induction furnace. In this work, the effects of the casting conditions, including superheat, rotation speed at one mould temperature have been investigated in terms of the product integrity and porosity and the microstructure of the valves. The mechanical properties and oxygen contents of cast stems with various degrees of superheat have been measured at room temperature. The as-cast car valves and some HIPped car valves have been successfully engine-tested. The feasibility for mass production of TiAl car valves and realistic costing for producing car valves using centrifugal casting and CaO crucible are currently also being assessed.