1997 Volume 69 Issue 2 Pages 119-126
The effects of casting conditions on solidification structure and banded segregation of Al-4.4%Cu alloy produced by centrifugal casting were investigated. Addition of grain refiner caused three zones in the radial direction ; equiaxed, fine equiaxed, and coarse equiaxed zone. Banded segregation was formed in the fine equiaxed zone obtained by horizontal centrifugal casting with smaller centrifugal forces than 100G. Smaller centrifugal force resulted in more numbers of banded segregation. No banded segregation was observed in the ingot obtained by vertical centrifugal casting. The effects of superheat and vibration were small. The grain size in the banded segregation was 150μm which was double that in the neighboring phases. Cu concentration was low in the equiaxed zone, and high in the fine equiaxed zone. It was about 5.6% in the banded segregation, larger than that in the neighboring fine equiaxed zone (about 4.9%). It is believed that the flow in the solid-liquid coexisting region caused by gravity force resulted in the banded segregation.
