Comparison of electropolishing behaviours of TSC, ALM and cast 316L stainless steel in H3PO4/H2SO4

In recent decades, new manufacturing processes have been developed such as Thermal Spray Coating (TSC) and Additive Layer Manufacturing (ALM), which reduce or avoid machining of parts with complex geometries. This study aims to develop an Electropolishing (EP) process for TSC and ALM 316L Stainless Steel (SS). EP is an anodic dissolution process currently used in industry to reduce surface roughness and obtain a bright and smooth finish. The EP mechanism was studied, in a mixture of H3PO4 and H2SO4, for TSC, ALM and cast SS in order to determine the best conditions (time, temperature, potential). Special attention was paid to surface characterization by combining several techniques (SEM, mechanical roughness meter, AFM, XRD) and using ISO standards. The EP surface was bright and smooth for cast and ALM materials despite differences in their structures. TSC samples electropolished in similar conditions did not exhibit the same behavior attributed to their diphasic structure. (C) 2017 Elsevier B.V. All rights reserved.