Simulation On Semi-solid Rheocasting Processing Based On Rheological Model

The Semi-solid alloy, used extensively in casting and rolling process is the pillar materials of the material processing. With the characteristics that the rheological model of semi-solid alloy can better represent and follow the tracks of variable viscosity in the process of alloy liquid, it has been applied by extensive and thorough ground in research. The Zinc-aluminum alloy with content of9%aluminum and AZ31magnesium alloy are taken as research objects. It focuses on variation of viscosity and influencing factor in the casting solidification processes. This paper mainly includes the following four aspects:1. This paper builds mathematical model of Zinc-aluminum alloy solidification under natural convection by the software of Fluent. It simulates solidification process under the assumption of Newtonian fluid and non-Newtonian fluid, and obtains distribution of temperature field, flow field and apparent viscosity. The result meshes to the temperature data gained by the trial.2. It also imitates the rheological cast-rolling process of AZ31, and gets the distribution of temperature field, flow field and apparent viscosity adopting the models of simple isothermal steady viscosity, carreau viscosity, simple continuous cooling viscosity and Newtonian fluid viscosity. By comparing the results, the more ideal viscosity model is carreau viscosity and the most ideal casting temperature is880K under this cast-rolling condition.3. The experimental casting simulation of semi-solid magnesium alloy of AZ31proves the non-Newtonian feature of shear thinning.This paper also analyses the correlations of apparent viscosity, temperature and shearing rate that apparent viscosity decreases with the increase of temperature and the enhancement of shearing rate.4. This paper does some research in the role of the viscosity playing in the process of heat conduction and convection of semi-solid alloy slurry solidification by the preliminarily experiments and numerical simulation and explains apparent viscosity has an important impact on static and dynamic fluid in the course of viscous momentum transmission from the micro particle Angle.