On the Effect of Exposure Time on Al-Si10-Mg Powder Processed by Selective Laser Melting

In this study, the effect of increasing exposure time on the microstructures, porosity, mechanical properties and corrosion behavior of selective laser melted sample Al-Si10-Mg powder was investigated. The samples were processed at the same power (375 W) and scan speed (2000 mm/s), but with increasing exposure time. Exposure time equal to 40, 50 and 60 μs was applied. The features of the analyzed samples show that with increasing exposure time, greater efficiency of the heat input was obtained, with a larger size of the melt pool and Si particles and lower porosity. Specifically, at the highest exposure time the melt pool showed an increase of 19% in width and 48% in depth, while the volume percentage of the voids decreased by 50% with respect to the lowest exposure time. Moreover, with the coarser microstructure being associated with a lower level of voids, the average hardness is similar for the analyzed samples. Corrosion resistance was evaluated, being one of the most important properties that may affect the service performance of Al-Si10-Mg alloy in the aerospace, marine and automotive industries. The potentiodynamic curves of the samples show that the voids occurrence is more significant with respect to the scale of the microstructure on corrosion behavior, with the sample processed at the highest exposure time being the more resistant to corrosion. The experimental techniques used in the present study were Optical Microscope (OM), Scanning Electron Microscope (SEM), hardness and X-Ray Computed Tomography.