Influence of Manufacturing Orientations on the Morphology of Alloy 718 Single Struts Manufactured by Selective Laser Melting

Selective laser melting (SLM) is of great interest for manufacturing lightweight structures such as lattices. It allows a broad range of lattice topologies to be created. However, when manufacturing small struts, roughness, lack of dimensional accuracy, and porosity level can decrease their mechanical properties and thus affect the mechanical response of the entire structure. This study focuses on the high-resolution characterization of alloy 718 (UNS N07718) single struts (constitutive elements of the lattice) manufactured by SLM. Process parameters, strategy, and post-treatments remain constant while varying strut positions on the build plate and orientations. A methodology for the systematic characterization of 19 struts with high-resolution X-ray tomography has been developed. Different features related to the strut size, shape, waviness, roughness, and porosity are extracted. The analysis of those features when varying strut positions and orientations highlights the influence of each parameter. The build orientation is a first-order parameter influencing strut morphology as already referenced in the literature. This systematic study reveals also the influence of the in-plane orientation for inclined struts that alters their roughness, shape, and size.