would have to be designed to optimize mechanical prop- erties and process cost. Additionally, the heat treatment of shape cast Al wrought alloys would be vastly different from net shaped components made by conventional solid- state transformation processes using these alloys due to the significant differences in the microstructure and phase formation in these components. Hence, it will be essen- tial to carry out a thorough and scientific investigation to define new heat treatment cycles for various shape cast


Al wrought alloys. The results of this study further show that it will be significantly beneficial to explore casting Al wrought alloys with the CDS technology in a pressure- assisted casting process such as HPDC and/or Squeeze Casting. Effective recycling of foundry returns is feasible in the shape casting of Al wrought alloy using the CDS technology. Examples of valid recycling schemes in cast- ing Al wrought Alloys 2024 and 7075 were presented in this study.


Figure 25. Typical thermal data recorded in the pouring cup during the tilt-pour casting trials of 2024 with CDS technology and 30% foundry returns recycling scheme (Table 8).


(a)


(b)


Figure 26. Typical microstructure of 7075 alloy cast in tilt-pour casting trails. The alloy 1 in this case had 30% by weight of foundry returns recycled from Alloy 3 (7075) castings to verify the foundry returns recycling scheme presented in Table 10. (a) CDS technology showing non-dendritic primary phase and (b) conventional casting of 7075 with 60C (140F) melt superheat showing dendritic primary phase.


62


International Journal of Metalcasting/Spring 11


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