Prediction of the yield strength and microstructure of a cast Al-Si-Mg alloy by means of physically-based models

Mechanical properties of age-hardenable Al alloys depend strongly on the characteristics of nanometric precipitates present in intra-dendritic regions during aging treatment. In particular, their shape, volume fraction and thermodynamic properties are the most influent aspects. Aside from precipitates, the yield strength is influenced also by solid solution strengthening and by the intrinsic strength of Al. The use of physically-based models, that is to say models based on physical quantities, has proved to be a very effective way to predict the yield strength of Al-based alloys during age hardening. Scope of this work is to model the dimensional kinetic evolution of strengthening precipitates of an Al-Si-Mg alloy during aging and use these results to estimate the alloy yield strength. To meet this target, the commercial software MatCalc was used, which is based on the Kampmann Wagner Numerical (KWN) model. The predicted dimensions of strengthening precipitates and their volume fraction are compared with experimental evidences obtained from STEM micrographs, while the resulting mechanical properties with tensile tests.