Heat Build-Up Effect on the Microstructure and Properties of Additive-Manufactured AlSi10Mg Parts

This study investigates the effect of heat build-up, as a function of different building modes and energy input, on the microstructure and mechanical properties of Al-Si10-Mg parts processed by Selective Laser Melting (SLM). Three different volumetric energy densities (67 J/mm 3 , 70 J/mm 3 and 86 J/mm 3 ) were applied for building samples. The building chamber was heated at 200 °C to reduce residual stress. The samples were processed in Horizontal (H) and Vertical (V) modes. The H and V samples were investigated using an Optical Microscope (OM), a Scanning Electron Microscope (SEM), x-ray diffraction (XRD), Vickers microhardness, and tensile tests. Moreover, the electrical conductivity (EC) of the samples was investigated . The amount, size, and morphology of the defects were also analyzed by Image J software. Different building modes significantly influenced the heat build-up, microstructure, and hardness at a set energy density. Vertical samples exhibited a coarser microstructure and reduced homogeneity along the growth direction ( z -axis) compared to horizontal samples. V samples also showed significant variations in microstructure and hardness along the z -axis, whereas H samples maintained greater uniformity. Furthermore, the percentage of defects increased in V samples and decreased in H samples with increasing heat input. Finally, after tensile test, a misalignment in mechanical response for H and V modes has been observed at all the energy densities except the lowest one.