Orientation dependency for microstructure, geometric accuracy and mechanical properties of selective laser melting AlSi10Mg lattices

The macroscopic mechanical properties of metallic lattice structures produced by additive manufacturing are key considerations in the design and application of multiscale structures. Indeed, these properties are relevant to the microstructure heterogeneities and geometric discrepancies that are severely influenced by the build orientation of struts in lattice structures. This report focuses on the effect of build orientation on microstructure, geometric accuracy and mechanical properties in AlSi10Mg samples produced by selective laser melting (SLM) and explores the microscopic mechanism of thermal transfer during melting via both experimental and simulation methods. The simulation results show that the cooling rate of the upper zone is two times larger than that of the lower zone with a wider thermal accumulation area. The experimental results indicate that the grain size and porosity of the lower zone of inclined struts with orientation angles are greater than those of the upper zone. It was determined that the deviation between the as-designed size and the as-built value for the inclined struts is minor, compared to that of vertical struts. In addition, the surface roughness of the inclined struts increases. Furthermore, the mechanical properties of the samples can be strengthened when the build orientation of the struts varies from 35.5° to 90°. The results of this study will facilitate the enhancement of the stability of the SLM manufacturing technique for metallic lattice structures in a robust and practical manner.