AlSi10Mg lattice structures produced by Selective Laser Melting : from microstructure characterization to impact resistance

More commonly known as 3D printing, the additive manufacturing (AM) technologies attract increasing interest in industrial sectors with stringent quality criteria. Amongst the different AM techniques, the selective laser melting (SLM) is a powder bed technology very much studied. Based on the local and progressive melting of a metallic powder, this SLM process allows the production of architectured designs heretofore inaccessible, in particular AlSi10Mg lattice structures. In the present work, the objective was to optimize the mechanical performances of these structures while minimizing their weight. Since these mechanical properties directly result from the microstructure, a multiscale characterization was performed. Microstructure heterogeneities have been identified as resulting from the lattice shape. Due to the inclination of the struts, a specific thermal history appeared inducing the formation of two zones, distinguished by their microstructure cell size and porosity. To erase these heterogeneities, several solution heat treatments have been performed. During these tests, the strong influence of the air atmosphere on the porosity enlargement was also reported. Thereafter, the quasi-static and dynamic mechanical properties of the structures have been studied, supported by 3D X-ray tomography images and analytical modelling. Under compression, a diagonal shear band was systematically observed. Moreover, the lattice geometry and heat treatment condition were identified as the main parameters influencing the load bearing capacity. Oppositely, the dynamic response of the lattice structures was mainly dictated by their configuration and size and not influenced by their microstructural changes.(FSA - Sciences de l'ingénieur) -- UCL, 201