Numerical study of solidification of A356 aluminum alloy flowing on an oblique plate with experimental validation

Abstract

Molten A356 aluminum alloy flowing on an oblique plate is water cooled from underneath. The melt partially solidifies on plate wall with continuous formation of columnar dendrites. These dendrites are continuously sheared off into equiaxed/fragmented grains and carried away with the melt by producing semisolid slurry collected at plate exit. Melt pouring temperature provides required solidification whereas plate inclination enables necessary shear for producing slurry of desired solid fraction. A numerical model concerning transport equations of mass, momentum, energy and species is developed for predicting velocity, temperature, macrosegregation and solid fraction. The model uses FVM with phase change algorithm, VOF and variable viscosity. The model introduces solid phase movement with gravity effect as well. Effects of melt pouring temperature and plate inclination on hydrodynamic and thermo-solutal behaviors are studied subsequently. Slurry solid fractions at plate exit are 27%, 22%, 16%, and 10% for pouring temperatures of 620 °C, 625 °C, 630 °C, and 635 °C, respectively. And, are 27%, 25%, 22%, and 18% for plate inclinations of 30°, 45°, 60°, and 75°, respectively. Melt pouring temperature of 625 °C with plate inclination of 60° generates appropriate quality of slurry and is the optimum. Both numerical and experimental results are in good agreement with each other.