Modeling of Porosity Formation in Aluminium Alloys

A new approach based on microsegregation of gas dissolved in the melt is used to model pore formation during the solidification of aluminum alloys. The model predicts the amount and size of the porosity in a solidified casting. Computation of the micro-/macro-scale gas species transport in the melt is coupled with the simulation of the feeding flow and calculation of the pressure field. The rate of pore growth is calculated based on the local level of gas supersaturation in the melt. The effect of the microstructure on pore formation is also taken into account. Parametric studies for one-dimensional solidification under an imposed temperature gradient and cooling rate illustrate that the model captures important phenomena observed in porosity formation in aluminum alloys. Comparisons between predicted porosity percentages and previous experimental measurements show good correspondence.