Microstructure, mechanical properties, and geometric deviations of additively manufactured LPBF-IN718 lattice structures

Abstract Additive manufacturing (AM) processes, such as laser powder bed fusion (LPBF), enable tool-free, layer-by-layer production directly from digital models, allowing for a wide range of design freedoms. However, support structures or fine, thin-walled lattice structures are necessary for producing overhangs or cooling channels. These structures can be used as functional geometries or must be removed later as temporary supports. Since these structures may have different properties than the main component, they can influence the manufacturing process. This study investigated the microstructure, hardness distribution, and geometric deviations of LPBF-manufactured support and lattice structures made of Inconel 718 (IN718). LPBF structures with layer-by-layer melt lines typically exhibit inhomogeneities both locally and within a series of samples. Geometric deviations, particularly reduced cell height in the build direction, must be considered when designing components such as heat exchangers. The findings of this study improve our understanding of the interactions between microstructure, mechanical properties, and geometric deviations in the LPBF process. These findings could contribute to the optimization of additive manufacturing technologies.