Influence of burnishing process on surface integrity of inconel 718 fabricated by laser powder bed fusion additive manufacturing

Abstract

This present study aims to contribute to the literature in understanding the roles of roller burnishing parameters and conditions on Inconel 718 alloy fabricated by Laser Powder Bed Fusion (LPBF). The roller burnishing process was performed with three burnishing forces (300 N, 600 N, 900 N) and under three cooling conditions (namely cryogenic, dry, and preheat). The effects on surface integrity characteristics including surface roughness, microstructure, microhardness, and XRD were investigated. The results illustrate that the burnishing force remarkably influences the decrease the surface roughness under all burnishing conditions. It was possible to reduce the surface roughness from 23 µm to 0.794 µm after turning applied to the as-built part followed by roller burnishing with 900N under dry conditions. When the microstructures were examined, the roller burnishing process caused plastic deformations and reductions in grain sizes. It was observed that the affected layer depth could reach 4.3 µm with 900N under preheat conditions. With the roller burnishing process, it was possible to increase the surface microhardness by 21% depending on the parameter and condition. The roller burnishing process had notable effects on XRD patterns of Inconel 718 alloy fabricated by LPBF.