Surface Polishing of Laser Powder Bed Fused Superalloy Components by Magnetic Post-treatment

The laser powder bed fusion (LPBF) process is one of an additive manufacturing method for the production of complexly shaped parts, which suffer from a rough surface, excessive residual porosity, and tensile residual stress in the near-surface layer. The magnetic polishing can be applied to improve the surface characteristics of complexly shaped and small-sized LPBF-built parts. This paper focuses on a study of the effect of magnetic treatment on the surface roughness, porosity, and hardness of Inconel 718 alloy parts printed by LPBF. The defects on the surface were also analyzed. Results indicated that applied magnetic polishing leads to a decrease in the surface roughness. The spherical or ellipsoidal balls and partially melted powder particles were successfully removed from the treated surface by magnetic treatment. The surface hardness was increased by about 20% in comparison with that of the LPBF-built specimen (32.2 HRC₁₀).