Effect of Nitrogen Content in a 18Cr-5Ni-10Mn Stainless Steel on the Pitting Susceptibility in Chloride Solutions

Anodic. behavior of 18Cr-5Ni-10Mn steels containing 0.07 to 0.35% nitrogen was studied in a 0.1N H₂SO₄ solution with additions of 0.01 to 0.1 N NaCl. The nitrogen content in these steels does not significantly affect their passive behavior but increases their pitting resistance. The most susceptible sites for pit nucleation are boundaries between the austenite matrix and some second-phase precipitates (presumably carbides). The effect of nitrogen on the pitting resistance of Cr-Ni-Mn steels is discussed with respect to their phase compositions.