Effect of nitrogen content on corrosion behavior of a high nitrogen austenitic stainless steel

Abstract

A series of electrochemical tests combined with scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray photoelectron spectroscopy (XPS) were used to study the effect of nitrogen content on the composition and structure of passive film of a high nitrogen austenitic stainless steel (HNSS) in 0.5 mol/L sodium chloride solution and its corrosion performance. The results showed that the proportion of low-angle grain boundaries in the HNSS increased with the increase of nitrogen content. Electrochemical results suggested that the HNSS with a higher nitrogen content had a lower corrosion current density in 0.5 mol/L NaCl solution and thus a lower corrosion rate. This was attributable to the formation of higher proportion of stable oxides (i.e., Cr2O3) in the passive film, accelerating the passivation process and promoting the corrosion resistance.