Research on a quantitative model of rheological distance by pressurizing

Abstract

In the pressurized rheoforming, such as squeeze casting, die casting and low-pressure casting, the filling and feeding processes are essentially related to the limit rheological distance of alloy melt under certain conditions. If the maximum rheological distance can be quantitatively predicted, it will be of great significance for the process design and quality control. Based on rheological model of non-Newtonian fluid and attenuation characteristics of temperature and pressure along the path, a quantitative model of rheological distance by pressurizing was established for heterogeneous complex structures of alloy melt including pure liquid, pure solid and semisolid with the solid-liquid coexistence during the process of pressurized rheoforming. It includes process parameters of pressurized rheoforming, material property parameters and mold structure parameters in this theoretical model, which can be used to predict the maximum rheological distance. The validity of the theoretical model was verified by comparisons between theoretical calculation values and length of the Archimedes spiral samples obtained by indirect squeeze casting using 6066 aluminium alloy. The results showed that the rheological distances calculated by this theoretical model coincided better with the experimental results and the maximum relative deviation was only 8.2%.