MACROSEGREGATION IN VERTICAL CENTRIFUGAL THIN-WALLED AND COMPLEX TC4 CASTINGS

This study investigated the macrosegregation in the thin-walled and complicated TC4 castings manufactured by a VCC (vertical centrifugal casting) process. The segregation mechanism and the effect of macrosegregation on the microstructure have also been studied. The results show that there is a trend of segregation in complicated casting produced by vertical centrifugal casting process. The macrosegregation at the thick-walled parts of the casting with complicated geometry shape is much obviously than that at the thin-walled parts of the casting. The cooling rate of the casting is the main factor to the formation of macrosegregation. The cooling rates at the thick-walled parts are much lower than that at the thin-walled parts, and the elements diffuse much more sufficiently at the thick-walled parts and the phase segregation occurs, therefore, there ultimately existed slightly elemental macrosegregation at thick-walled parts.