Cyclic potentiodynamic passivation of 316L stainless steels of different crystallographic orientation produced by laser powder bed fusion: Towards the improvement of corrosion resistance

Abstract

The influence of cyclic potentiodynamic passivation (CPP) of 316L stainless steels (SS) of different crystallographic orientation produced by laser powder bed fusion (LPBF) on the resulting general and pitting corrosion resistance is discussed. CPP was performed by cyclic voltammetry in aqueous 0.1 M NaNO3. Electrochemical tests including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and linear potentiodynamic polarization were employed to evaluate the resulting corrosion properties of the surfaces in aqueous 3.5 wt.% NaCl. It was found that the CPP method enables the formation of a passive oxide surface film which significantly improved the materials' general and pitting corrosion resistance in comparison to the naturally‐formed passive film under the experimental conditions investigated. It was also found that the general corrosion resistance, for both the unmodified (naturally‐passivated) and CPP‐modified LPBF 316L samples, decreased in the order of {111} > {100} > polycrystalline > {110}. Although the CPP‐modified samples showed a significantly lower current in the passive region and higher pitting potentials, in comparison to the unmodified samples, their crystalline structure was found not to have any influence on the corresponding behaviours.