Modelo matemático multigrãos e multifásico para a previsão da solidificação equiaxial. / Multigrain and multiphase mathematical model for prediction of the equiaxed solidification.

AUTOR(ES)

Davi Teves de Aguiar

DATA DE PUBLICAÇÃO

2011

RESUMO

Properties of components obtained by solidification processes depend strongly on the final grain structure. In the past few decades, there has been a significant breakthrough in the mathematical modeling of metallic alloy solidification to predict the grain macrostructure. Nevertheless, the so-called deterministic models are still not capable of modeling the individual growth of grains throughout the solidification time. The objective of the present work it to propose, implement, and evaluate a multiphase and multigrain mathematical model of equiaxed solidification in binary alloys. The equations of the model are based on the macroscopic conservation equations of mass, energy, and chemical species. The main feature that distinguishes the present model from other models available in the literature is the consideration of the growth of individual grains of different sizes, and of the dendritic or globulitic growth. The macroscopic conservation equations of mass, energy, and chemical species were applied separately to each class of grains of different sizes. The results obtained from the present model were compared with those from a model that also simulates the individual growth of grains, but was developed only for the early stages of solidification, during which there is globulitic growth. Next, the results were compared with those from a similar model, but which does not consider the individual growth of grains, following only a grain of average size. A parametric analysis was carried out with the present model, which was later used to simulate different experiments presented by several authors. The model was capable of simulating several phenomena, including the globulitic and dendritic growth for each class of grain, during the whole solidification time. The results obtained with the present model reproduce very accurately the cooling curves and the prediction of grain size obtained from a model that considers only a grain of average size. The present model results are in close agreement with measurements of average grain size and grain size distribution in an commercially pure Al with different additions of Al-5%Ti-1%B.

ASSUNTO(S)

mathematical modeling modelagem matemática solidificação solidification

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