Electropolishing of Inconel 718 manufactured by laser powder bed fusion: Effect of heat treatment on hardness, 3D surface topography and material ratio curve

Abstract

In the present study, the laser powder bed fusion (LPBF) technique was used to produce Inconel 718 parts as a fabrication route. The LPBF processed samples microstructure, and surface characteristics were analyzed in both the as-printed and heat-treated conditions. The surface irregularities in the as-printed Inconel 718 was minimized using the pulsed electropolishing technique. The weld bead along the build direction and laser scan path to the build direction was observed. The electropolished results showed that increasing the current density and polishing time decreases the areal surface roughness of the as-printed sample (~64%) and heat-treated sample (~54%). The material ratio curve shows an increase in current density and electropolishing time

the surface topography becomes more uniform and lesser surface undulations for the as-printed samples and less uniform in the case of heat-treated samples. It was attributed to the interplay between microstructural constituent phases and electropolishing process parameters. The material ratio curve serves as an effective method to assess and qualify the surface characteristics of the electropolished LPBF processed samples. Furthermore, the 2D line profilogram and 3D surface topography benefit better understanding the surface finish quality characteristics of electropolished LPBF processed samples. © 2021