Electropolishing of CuZn brasses and 316L stainless steels: Influence of alloy composition or preparation process (ALM vs. standard method)

Abstract In the present paper, electropolishing behavior of different brass alloys (CuZn 39 Pb 2 , CuZn 42 ) in phosphoric acid is studied to observe the impact of alloying elements on polishing quality. In the same way, the influence of the manufacturing process is also evaluated through the comparison of a “standard” stainless steel and a stainless steel prepared by Additive Laser Manufacturing (ALM). An electrochemical study was first performed to determine the best treatment conditions for each material/electrolyte pair and to study the electropolishing mechanism and its kinetic dependence on diffusion. Metallic samples are fully characterized before and after electropolishing in their respective electrolytes so that a relationship to manufacturing variables, crystallographic properties and microstructure can be established. While the biphasic composition of brasses studied here leads to a preferential attack of the β phase, somewhat difficult to manage, the presence of lead in copper alloy does not really disturb the process, even if lead particles are not removed from the surface. Furthermore, the manufacturing mode seems to play an important role in stainless steel polishing. The metallographic studies highlight a difference in microstructure between the two kinds of samples and reveal that they do not have the same crystalline organization even after a mechanical pre-treatment. This had to be taken into account in the global process organization.