Electrochemical polishing of selective laser melted Inconel 718

Electrochemical polishing (ECP) was utilized to produce sub-micron surface finish of Inconel 718 parts manufactured by selective laser melting. Titanium electrode was used with an acid-based electrolyte to polish specimens at different combinations of pulsed current density, duty cycle, and polishing time. Digital 3D optical profiler was used to assess the surface finish, while scanning electron microscopy was utilized to observe microstructure of polished specimens. At optimal condition, ECP successfully reduced the as-printed surface finish from 17 mu m to 0.25 mu m; further polishing did not improve the surface finish due to different removal rates of micro-leveled pores, cracks, nonconductive phases, and carbide particles in 3D-printed Inconel 718. Homogenizing and hot-isostatic pressing should be done before ECP for uniform polishing. (C) 2019 The Authors. Published by Elsevier B.V.