Evaluation of the impact behaviour of AlSi10Mg alloy produced using laser additive manufacturing

In the present study, instrumented impact strength tests were carried out on Charpy AlSi10Mg samples produced using laser additive manufacturing in order to accurately investigate the influence of building directions, heat treatment parameters and also the effect of Hot Isostatic Pressing (HIP) on their impact properties. AlSi10Mg cast samples were also tested for comparison. In addition to metallographic inspections, a deep characterization of the fracture surfaces in all the analysed conditions was performed. Microstructural features were also correlated to the impact properties: absorbed energy, peak force, crack nucleation and propagation energies. It was found that additive manufactured samples in as-produced condition exhibit the best performance due to their peculiar microstructure. HIP, followed by T6 heat treatment, is positive for the alloy properties since it effectively reduces porosities, which are a favourable path for crack propagation. Building direction has a clear effect on the fracture propagation. Samples in as-produced condition display greater unevenness of the fracture surface in the horizontal direction than in the vertical direction. This trend is less evident after heat treatment, but still detectable. The fractal dimension of the fracture surfaces is a quantitative parameter sensitive to the building orientation of samples and to the performed heat treatments.