Modelling the creep behavior of an AlSi10Mg alloy produced by additive manufacturing

AlSiMg alloys produced by additive manufacturing possess an extremely fine and complex microstructure that in many ways defies the most widely used phenomenological models, which, in fact, have turned out to be poorly suited for predicting their mechanical properties. The underlying rationale for the peculiar properties of these alloys has been qualitatively established, however the need for a constitutive model with better predictive capability is still strong. To this aim, the ultra-fine microstructure was described by using a model-material (MM) consisting of soft and hard zones deforming under a similar strain rate. A physically-based set of constitutive equations which took into account also the coarsening/ripening phenomena of the Si-particles was used to predict the creep behavior of the MM. In parallel, the creep response of an AlSi10Mg alloy produced by additive manufaturing and tested in the as-deposited condition was investigated at temperatures ranging from 150 to 225 °C. The minimum creep rate curves obtained for the MM by the constitutive model were then compared with the experimental data obtained by testing the real alloy under constant load in different initial states. The excellent correlation between model curves and experimental results was discussed, taking into account the evolution of the microstructure during creep.