Electrochemical noise studies of the effect of nitrogen on pitting corrosion resistance of high nitrogen austenitic stainless steels

Pitting corrosion studies were carried out on nitrogen containing stainless steels (SS) in 0.01 M FeCl3 using Electrochemical Noise (EN) technique. Shot-noise parameters like characteristic frequency of corrosion events, fn and characteristic charge, q and noise resistance (RN) showed that with increase in nitrogen the tendency to undergo pitting corrosion decreases. A plot of maximum pit depth, Pitmax vs. nitrogen content showed that, Pitmax decreased with increase in nitrogen content and followed a parabolic relationship. A new parameter, charge ratio was defined; it was observed that charge ratio values decreased with increase in nitrogen content.

► Total number of current transients decrease with increase in nitrogen content.
► High nitrogen containing stainless steel showed better passivability.
► Shot-noise parameters showed that high nitrogen increased pitting resistance.
► Pitmax values decreased parabolically with increase in nitrogen content of SS.