Computational modelling of the extrusion of an Al-SiC metal matrix composite using macroscale and microscale methods

This paper explores the use of both macroscale and microscale modelling for the analysis of extrusion of an AA2009 + 25%SiC_p metal matrix composite (MMC). The performance of a micromechanical model, where the heterogeneous microstructure of the MMC is explicitly modelled, in predicting the tensile stress—strain behaviour of an AA2009 + 25% SiC_p MMC is examined. A macroscale modelling approach is used to simulate extrusion of the MMC through two different die designs, where the MMC is modelled as a homogeneous continuum. Firstly, the extrusion results are used to compare the two die designs, to determine which is the more favourable. Secondly, the predicted macroscale plastic strain distributions and pressures are used with the micromechanical model to assess microscale stress states in the material during extrusion with a view to gaining insights into the risk of damage in the material. In this context, pressure is shown to be hugely important in controlling tensile stress magnitude and in reducing microscale damage risk, and essentially ensuring that extrusion can be achieved in practice. However, the results reveal that damage risk is not totally eliminated and that there may still be locations where the material may rupture.