Thixoforming technology requires a feedstock with a globular microstructure rather than dendritic microstructure used in conventional casting methods. In the present investigation, several AA7075 wrought aluminium alloy feedstock were produced using cooling slope (CS) casting technique at different fabrication conditions. Optimization of the CS casting process parameters was conducted to find out the optimum conditions that achieve the best microstructural characteristics of the feedstock. Moreover, correlations for microstructural characteristics as functions of CS casting process parameters were determined. The results revealed that the optimum values of pouring temperature, cooling length and tilt angle were found to be 650 °C, 350 mm and 45°, respectively. Billets fabricated under such conditions showed the minimum average size as well as the maximum shape factor of á-Al primary grains. The pouring temperature is the most influential parameter on both the average grain size and shape factor of the primary á-Al grains.The developed empirical correlations were successfully used to predict the average grain size and shape factor of the AA7075 alloy billets produced using CS casting technique. |
