Optimisation of process parameters for an additively manufactured AlSi10Mg alloy: Limitations of the energy density-based approach on porosity and mechanical properties estimation

Due to the high complexity of the Additive Manufacturing processes, the effect of individual deposition parameters on integrity and mechanical performance of the 3D-printed part is not easily assessable. An energy density-based approach is often adopted to overcome such complexity, being the Volumetric Energy Density (VED) one of the widely used parameters. However, previous works on the AlSi10Mg alloy suggest that fully dense parts could be achieved with a well defined VED range. This study investigates different combinations of deposition parameters to reproduce part of this range and assess its effect on porosity, microstructure and tensile properties of the AlSi10Mg alloy. It was found that different combinations of deposition parameters in the employed VED range did not alter the microstructural features significantly. Conversely, they severely affected porosity, showing that VED is not a reliable parameter to predict the final density of the additively manufactured components. Moreover, specimens produced with a similar VED but different hatch spacing exhibit significantly different tensile properties. This fact suggests that the effect of deposition parameters should not be solely related to the amount of energy imparted to the material. Finally, systematically higher tensile properties characterise our specimens compared to results available in the literature, due to the microstructure obtained with the adopted combination of deposition parameters. The energy density-based approach lacks in considering the effect of process parameters on the microstructural features other than porosity, which could identify their actual proper combination misleadingly. Our results suggest that new approaches to define the optimum choice of process parameters need to be evaluated to maximise the final performance of AM components.