Electrochemical investigation of the influence of nitrogen alloying on pitting corrosion of austenitic stainless steels

A systematic investigation has been performed of the influence of nitrogen alloying on the pitting corrosion of austenitic stainless steels. The alloys investigated had a base composition of 20% Cr–25% Ni with 0% or 4.5% Mo. The nitrogen level was varied up to the solid solubility limit at approximately 0.2%. The critical temperature for pitting corrosion increases with nitrogen additions and the effect is more marked in the molybdenum-alloyed steels, indicating a synergistic interaction between the two alloying elements. A number of investigations have been performed to elucidate the mechanisms for the influence of nitrogen on pitting corrosion and for Mo–N synergism.