In-situ Determination of the Precursor Sites for Pitting Corrosion on Duplex Stainless Steels

Pitting Corrosion of Duplex Stainless Steels (DSS) normally occurs at temperatures above the Critical Pitting Temperature (CPT). Below the CPT, metastable events can occur. However, at the CPT, stable pitting is possible. Of particular interest is the determination of precursor sites for pitting in these materials (i.e. sigma phase, inclusions etc). In this work, we study in-situ the precursor sites for pitting of a 25% Cr DSS using both electrochemical techniques as well as in-situ microscopy under a chloride containing solution (above room temperature).