Three modes of plasma electrolytic polishing of high-alloy austenitic steel

Three different modes of plasma electrolytic polishing (PEP) of additively manufactured high-alloy austenitic steel specimens, which were fabricated using a powder bed fusion electron beam (PBF-EB/M) technology, were investigated in this study. Namely static bath-PEP, dynamic bath-PEP and standing-wave-PEP. All specimens were PEP treated for 30 min in total. The process efficiency was evaluated in terms of the achieved surface roughness reduction in selected parameters Sa, Sq and Sv, and material removal rate in terms of ablated material weight and volume. The most consistent and reproducible results were achieved by applying the bath-PEP method, regardless of the used mode. The standing-wave-PEP mode, on the other hand, demonstrated the highest efficiency and highest locally achieved surface homogeneity. Nevertheless, the standing-wave-PEP proved to be the most demanding for the precise control of the process parameters and high accuracy in positioning the specimens. The maximum surface roughness reduction achieved by the static bath-PEP was 77.5 %, 76.9 % and 46.1 % for Sa, Sq, and Sv, respectively, by the dynamic bath-PEP 87.7 %, 86.3 % and 60.3 % for Sa, Sq, and Sv, respectively, and by the standing-wave-PEP 89.4 %, 88.3 % and 64.7 % for Sa, Sq, and Sv, respectively.