Pitting Initiation on Stainless Steels: Electrochemical and Micrographic Aspects

Publisher Website
Google Scholar
Abstract
Pitting initiation has been studied on several austenitic and ferritic stainless steels (SS) in contact with an oxidizing chloride solution (sodium hypochlorite at 70 C). Systematic micrographic inspection of the SS surface has been performed after recording electrochemical curves vs time (free potential and current intensity under potentiostatic control). Repassivated pits that do not propagate and active pits that continuously dissolve have been observed. The initiation of both pit types depends not only on the alloy potential, but also on the duration of contact with the solution. According to the value of these parameters, repassivated pits either do not involve any visible attack or give rise to localized bulk lattice dissolution, but they are never the origin of an active pit. Such an electrochemical behavior, together with micrographic data, suggests that two distinct mechanisms can be involved in the pit initiation stage.

This publication has 0 references indexed in Scilit: