The Effect of Flow Velocity on Pitting Potential of Nitrogen Containing Stainless Steels

Abstract

By using a flow channel method, the effect of the flow velocity on pitting potential of Type 304 stainless steels with different levels of nitrogen has been studied. Pitting potential was measured by a potentiokinetic method in 3.5%NaCl saturated with nitrogen gas at 303K. Distribution of measured values of pitting potential obeyed a normal probability distribution, mean of which was found to increase with increase of the nitrogen content in the steels. The mean value of pitting potential shifted to the noble direction with increase of the flow velocity in laminar region, approaching a constant value in turbulent region. A lower flow velocity dependence of pitting potential in laminar region was observed for the higher nitrogen steels.