ingot used to make the Alloy 1 melt as shown by the notation “Ingot 1” in Table 9. This table shows that recycling foundry returns is viable for the CDS process and a table similar to Table 9 would have to be constructed for each Al alloy (Alloy 3) intended to be cast into a shaped component.


Figure 24 shows typical microstructure of Alloy 2024 cast with CDS technology (Figure 24a) and conventional technology with a 60C (108F) melt superheat for the al- loy (Figure 24b). The CDS process was carried out with


Alloy 1 having 30% by weight of foundry returns from the Alloy 3 (2024) castings. Figure 24(a) shows that the CDS process yielded a non-dendritic morphology of the primary phase in the microstructure whereas the morphol- ogy of the conventional cast 2024 sample in Figure 24(b) has a dendritic primary phase.


Figure 25 shows the typical thermal data obtained from the pouring cup during the tilt-pour casting of Alloy 2024 with


(a)


(b)


Figure 24. Typical microstructure of 2024 alloy cast in tilt-pour casting trails. The alloy 1 in this case had 30% by weight of foundry returns recycled from alloy 3 (2024) castings to verify the foundry returns recycling scheme presented in Table 8. (a) CDS technology showing non-dendritic primary phase and (b) conventional casting of 2024 with 60C (140F) melt superheat showing dendritic primary phase.


Table 8. Tensile Properties of Alloys Cast in Tilt-Pour Casting Trials with CDS


International Journal of Metalcasting/Spring 11


59


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