Effect of viscosity on microstructure characteristic in rheological behaviour of wrought aluminium alloys by compression and stirring process

Abstract

Compression and stirring tests were performed to investigate the rheological behaviour of wrought aluminium alloys with varying processing parameters, such as liquid fraction, strain rate, shear rate and materials. The present paper shows the results of an experimental investigation using Al2024, Al6061 and Al7075. Specimens of each aluminium alloy were characterised by their rheological behaviour during partial melting and holding in the semisolid state. The compression and stirring tests allow the apparent viscosity of the alloys to be determined as a function of the liquid fraction and shear rate. Moreover, the change of grain size and shape was examined by considering shear rate, stirring time and liquid fraction during stirring. These experimental results could be used in flow and solidification analyses and could be useful for manufacturing good rheological products by observing the microstructures according to changes in solid fraction and compression rates.