Enhancing mechanical properties of double-periodic lattice structures using hybrid-additive manufacturing

Abstract We report on a study of the mechanical properties of hybrid-additive manufactured Inconel 718 double-periodic lattice structures. For this, a hybrid approach, combining Laser Powder Bed Fusion (PBF-LB/M) and in-situ high-speed milling, is employed. Within this technique, the PBF-LB/M process is interrupted after several layers, as the milling process starts, enabling a machining of inlaying structures. As the surface quality is improved up to $$\varvec{R}_\text {a}$$ = 0.8 µm, in turn, improving the mechanical properties, the static and dynamic behaviour of PBF-LB/M and hybrid built components is compared. Here, in particular, lattice structures, precisely double-periodic arranged hexagonal unit cells, are considered. To evaluate the periodic structures, the compression strength, Young’s modulus, as well as the endurance limit are determined, quantifying the effect of surface improvement by the hybrid approach. With an increase in compressive strength from 95.7 MPa to 142.7 MPa ( $$\approx$$ 50 %) and an enhancement of about 140 % in endurance limit (16 MPa to 39 MPa), the effect of surface improvement by the hybrid approach is quantified. Furthermore, the direction of loading, the surface quality and its impact on the fracture behaviour are investigated for an accurate analysis of the structures.