Additive Manufacturing includes a broad range of different processing techniques. Most of these techniques enable realization of complex and filigree structures like fine struts or periodic lattices, which cannot be processed by conventional techniques like milling or drilling. Due to a very high design flexibility and hardly any constraints, powder bed fusion processes have shown to be suitable for manufacturing of periodic lattice structures. Especially because of the very high process temperatures and slow cooling rates only low thermally induced residual stresses remain in Electron Beam Powder Bed Fusion (PBF-EB/M) processed periodic lattice structures.

Focusing on the deformation behavior of such fine structures, fatigue life is significantly affected by surface roughness. Additionally, inner defects or, considering specific alloys like IN718, heterogeneous microstructures have to be considered as well [1]. The smaller the structures, the higher is the contribution of surface roughness to the fatigue life. For complex geometries post processing of surface features is hard to realize. However, it is known, that the adaption of process parameters and scanning strategies can effectively alter surface roughness [2], relative density, microstructure, or final feature size. Thus, one should consider in advance the correct process settings to minimize the effort needed for post processing. What can be done to optimize IN718 lattice structures processed via PBF-EB/M, and how sensitive small features react to process adaptations will be scope of this work.

References

[1] D. Kotzem, Mater. Sci. Eng. A, 2020, 772, 138785.
[2] C. Körner, Modelling Simul. Mater. Sci. Eng. A, 2013, 21, 085011 (18pp)