Damage modelling of an aluminum cast alloy accounting for pore morphology

In this work a die casting component (Y-box) from the aluminum alloy Castasil®-37 (AlSi9Mn) is characterized under different stress states obtained from tests with uniaxial tensile, notched tensile, shear tensile and biaxial specimens. A large scatter of local material properties, especially the failure behavior, has been pointed out and could be related to inhomogeneous microstructure and porosity. The Markov random field model (Ising) is used to describe the pore morphology dependent microstructures. Markov random field classes are defined by porosity and equivalent pore size both determined by computer thomographie (CT) analysis. A multi scale approach is applied to map the results of the stochastic model to the FE models. Within the proposed method a porosity distribution is used to de scribe the microstructure. A porosity dependent continuum model is developed and calibrated from the results of representative volume elements. It takes into account the influence of porosity and triaxiality on deformation and damage behavior. It is shown that the continuum model with porosity distributions from the Ising model as initial conditions well captures the stochastic character of the material behavior (i.e. fracture strain) under different stress states.