On microstructure and corrosion behaviour of AlSi10Mg alloy with low surface roughness fabricated by direct metal laser sintering

•Increasing the volumetric-energy-density during DMLS reduces the surface roughness.•Decreasing the hatch-distance forms a periodic large and small melt pools pattern.•The larger melt pools revealed coarser microstructural features.•The larger melt pools control the overall corrosion resistance of the part.•Faster solidification rate along melt pool borders improves the corrosion behavior. In this study, in-depth microstructure and electrochemical properties of highly smoothed AlSi10Mg parts fabricated through direct-metal-laser-sintering are reported. The samples with the lowest surface roughness were characterized by having a periodic large and small melt pools (MPs) pattern in their upskin layers. Consequently, a noticeably coarser eutectic-Si network, Al-dendrite and grain size formed along the larger MPs’ borders, rationalized by their slower solidification rate. Such microstructural features were found to control/deteriorate the electrochemical performance of the as-printed samples than their surface roughness. An improved electrochemical stability for the samples that experience the fastest solidification rate along their MP-boundaries was revealed.