MICROSTRUCTURAL MODELING OF SOLIDIFICATION IN A356 ALLOY

Macro-micro models assume a constant Value for maximum nuclei density, n(0), to predict the microstructure. This assumption may not be valid for all casting processes and process conditions. In an earlier article, maximum nuclei density was observed to vary with the casting process and pouring temperatures. Here, a macro-micro model was developed to simulate the formation of the primary and the eutectic phases in A356 alloy. The castings were simulated using this model with a constant maximum nuclei density (constant n(0)) and with the maximum nuclei density values obtained experimentally (varying n(0)). There was reasonable agreement between simulated and experimental results. Varying n(0) assumption resulted in a close agreement between simulated and experimental grain sizes, relative to constant n(0) assumption. This work brings out the need to determine the maximum nuclei density prior to its usage in macro-micro models.