A coupled temperature-shear rate viscosity model for non-heat-treated aluminum alloys: Development and die casting application

The rapid development of integrated die casting technology for lightweight automotive components demands high-precision modeling of melt flow behavior, especially for non-heat-treated (NHT) aluminum alloys. This work systematically investigates the rheological properties of an NHT aluminum alloy over a wide temperature range from semi-solid to fully liquid states. A double-cylinder rheometer was employed to measure the viscosity of the alloy under multiple isothermal and shear rate conditions. A new viscosity model incorporating both temperature and shear rate effects was developed. The accuracy and applicability of the proposed model were validated through high-pressure die casting experiments and numerical simulations using an S-shaped ultra-long flow length casting. The results demonstrate that the proposed model, which captures the non-Newtonian behavior of the aluminum alloy melt, predicts filling length with much higher accuracy compared to previous temperature-dependent viscosity models. The simulation error is reduced by 68.78%, and the predicted filling length closely matches the experimental results. This work provides a reliable rheological model for NHT aluminum alloy melts, enabling more precise numerical simulation and process optimization for integrated die casting.