[16P-T6-07] Effect of Line Energy on Side Surface Roughness of Ni-Based Superalloys in Powder Bed Fusion-Electron Beam
キーワード：Powder bed fusion electron beam melting process, Ni-based superalloy, Surface roughness, Multi-physics model, Computational fluid dynamics
The optimization of the side surface roughness of the as-built part is one of great interest in the powder bed fusion-electron beam (PBF-EB) because of the post-processing difficulty. In this study, the generation mechanism of the side surface in the PBF-EB was investigated using Ni-based superalloy under different line energies. The dimensional inaccuracy of the as-built part mainly attributes to part diameter variation rather than part height variation. The side surface roughness of the as-built part increased with increasing line energy owing to the formation of wavy bulges. The multi-physics model was developed to investigate the side surface generation in the PBF-EB. The right-angled stair edge was relaxed at high line energy owing to the increased molten pool dimension. The molten pool convection via the Marangoni effect was increased at high line energies because of the large difference in the temperature with low viscosities. The formation of wavy bulges on the side surface originated from the severe heat accumulation at the last solidified region in each melting path under high line energies. Therefore, it was confirmed that the side surface roughness in the PBF-EB can be improved by optimizing the line energy to restrict the formation of wavy bulges and coarse particles.