Pressure effect on Al alloy cast behaviour: microstructures and mechanical properties

Dealing with pressure-assisted fabrication processes of aluminium alloys, the applied pressure has a double effect, a direct and an indirect one. Except for porosity, the direct effect is connected to the thermodynamic equilibrium modification and the indirect effect is related to the cooling rate variation. A Suitable apparatus was built and an experimental procedure was carried out in order to investigate both pressure effects, showing the predominance of the indirect one. Microstructural analyses and mechanical tests were performed for this aim. A FE numerical model was implemented in order to correctly assist the experimental activity too. Starting from the evidence of the greater importance of the pressure indirect effect, a model was proposed so as to predict the alloy mechanical properties as a function of the cooling rate. The proposed model allows to realise important process considerations and is the first step in order to predict the final performances of a given aluminium alloy component when the geometry and the process parameters employed during fabrication are known.