Parts produced by additive manufacturing (AM) processes used metal powders are characterized by the high surface roughness. The potential applications of AM parts depend on suitable finishing technologies that ensure the surface quality needed to achieve the desired functionality and performance. Several post-processing methods have been evaluated, such as mechanical, electrochemical, chemical, laser, or their combinations. While these methods have reduced roughness, many of them could not to treat the entire surface of complex-shaped AM objects effectively and evenly [1, 2]. The paper focuses on the plasma-electrolyte process to treat the AM parts surface. In this process, the function of tool for reducing roughness is performed by electrical discharges between the machined surface and the electrolyte, and the internal movement of the vapour-plasma layer created by these discharges and evenly surrounds the entire treated object [3, 4]. 

The suitability of plasma-electrolytic process for surface post-processing and reducing roughness of objects produced by selective laser melting was verified on samples of AISI 316L steel printed on a Renishaw AM400 3D printer. Experimental work carried out on a 6 kW device with 4% electrolyte showed that the plasma-electrolytic process in anode mode can effectively reduce protrusions in the form of adhered particles and macroroughness of the complex-shaped objects’ surface from an initial average roughness of Ra 5–7 μm to 2–3 μm in 180 seconds, when the treated surfaces are characterized by high integrity and are free of oxide layers.