Through thickness variations of deformation texture evolution in AlMgSi-extrusions: experiments, FEM and crystal plasticity modelling (Keynote)

The mechanical properties and surface appearance of aluminium extrusions are critically dependent on the microstructure and texture of the extruded profiles, where the requirements depend on the applications. The key to understand and predict the final (recrystallized) structure, both in terms of grain structure and texture, is the deformation microstructure and texture. In the present work, the deformation texture and its through-thickness variations during both round and flat profile extrusion of an AA6063 aluminium alloy have been experimentally measured by the electron back-scatter diffraction technique (EBSD), and numerically modelled by coupling FEM flow simulations and crystal plasticity simulations. Different crystal plasticity models as well as different choices of model parameters were employed and evaluated for texture predictions. A careful analysis of the deformation history from the FEM simulations reveals how the deformation conditions changes during extrusion in terms of through thickness variations as well as along a deformation path (from the container, through the die and into the extruded profile) and is used as basis to interpret the as-extruded deformation textures. It is further concluded that with an appropriate choice of crystal plasticity model and model parameters, the deformation textures and their through thickness heterogeneities can be well predicted.