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Prediction of grain structure and texture evolution after high temperature extrusion of aluminum alloys Khajezade, Ali


To engineer the mechanical response of the material, it is crucial to predict the microstructure after thermomechanical processing and relate properties to the microstructure. In this study, the relationship between the features of the deformed state after axisymmetric extrusion of aluminum at high temperatures (e.g., the subgrain size distribution and the disorientation distribution) and the final recrystallized texture was investigated. It aims to systematically change the features of the deformed state by generating different initial synthetic microstructures and using them as inputs for a phase field model to predict the recrystallized texture. The characteristics of the deformed state and the recrystallized state were analyzed for extruded 3XXX aluminum samples with two different homogenization heat treatments. The subgrain size distribution and disorientation distribution in different texture fibres of the deformed state, i.e., <001>||ED and <111>||ED, were extracted to construct a baseline condition. After verifying that 2D simulations could be used to capture the essential phenomena in 3D, the role of the microstructural features was investigated using 2D simulations. First, the subgrain size distribution and disorientation distribution were changed from baseline condition by ±50% for individual grains with <001>||ED or <111>||ED. Second, for a mixture of grains with <001>||ED and <111>||ED orientations, <111>||ED baseline condition was used, then subgrain size distribution and disorientation distribution were changed by ±50% for <001>||ED grains. Third, an input microstructure from experimental EBSD measurements was simulated. For the first scenario, a narrower distribution and a wider disorientation distribution resulted in a larger final average subgrain size which was rationalized based on the evolution of these microstructural features. For the second scenario, the tail of the subgrain size distribution and the width of disorientation distribution within <001>||ED was found to have a large impact on the final texture. This was explained by the probability of large grains with high angle disorientation in <001>||ED fibres growing preferentially to pinch-off grains with <111>||ED orientations. For the third scenario, only <001>||ED volume fraction could be predicted accurately compared to the experiment. Possible sources of error were identified and discussed.

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