Metal Additive Manufacturing Conference 2019

Among additive manufacturing technologies, selective laser melting (SLM) is characterised by high solidification cooling rate. SLM can promote the formation of metastable phases and the effects of heat treatments on SLMed parts can be quite different respect to cast material. This has already been demonstrated for AlSi10Mg alloy. Not only the precipitation of hardening phases, like Mg2Si, was affected but also the cellular silicon network underwent morphological modifications, which can influence the mechanical properties. Similar behaviour could be expected for other Al based alloys, characterised by the presence of both ‘stable’ secondary phases and metastable phases, which contribute to precipitation hardening. In the present work, two aluminum alloys, AlSi10Mg and A205, both characterised by an high castability and good mechanical properties after thermal treatment, were studied. As built microstructure similarities and differences are discussed in view of thermal treatment optimisation. Calorimetric analysis and microhardness measurements were carried out for studying the precipitation phenomena and the mechanical properties of the alloys, respectively. Finally, a comparison between the characteristics of the SLMed parts and the initial powder was taken into account for considering the effect of different values of cooling rates.