Application of Rheological study to characterize the microstructure of SSM Rheo-Cast Billets

Abstract

Manipulation of pouring temperature is an efficient way to produce different microstructural features. In order to characterize the microstructure of rheocast billets due to different superheats of 615-695 °C, the parallel plate compression method was employed. Foundry 356 Al-Si alloy with different morphologies of primary α-Al particles were tested at different initial pressures of 4.8, 11.2 KPa. The resulted strain-time graphs were further treated mathematically to calculate viscosity of SSM billets. The interrelationships of viscosity, the microstructure and primary phase flow during compression are discussed. It is shown that the dendritic primary α-Al structure has the highest viscosity number which is almost three orders of magnitude greater than those for globular morphology. The current research have, for the first time, shown the validity and reliability of “parallel plate compression viscometry” method in characterizing microstructural evolution of Rheocast SSM billets.