Abstract

Laser powder bed fusion method is popularly applied in the additive manufacturing of
metal parts. The void defect and microstructure are the main factors which determine their
mechanical properties. However, the characterization of microstructure and cavities is two
dimensional, which is hard to show the spatial profile. In this paper, in order to explore
the microstructure and defects in three dimensions, the combined continuously slicing and
microstructure observation was used to investigate the microstructure of an Inconel 718
sample. The sample was sliced 468 layers with thickness of 1 μm by xenon ion beam, a
142.8 μm* 107 μm* 46.8 μm microstructure cube was reconstructed. From the 3D model,
the melt pool, cavity, pore and grains and their orientations were analyzed. The results
provide spatial features of its microstructure. The equi-axed grains are among the coarse
column grains, and some are the original grains of insufficiently melt or totally unmelt
powder particles. The results tell the difference of the two kinds of voids, i.e., cavity and
pore.

Keywords

laser powder bed fusion, Inconel 718, microstructure, 3D characterization, pore, cavity