Use of the electrochemical microcell technique and the SVET for monitoring pitting corrosion at MnS inclusions

The purpose of this paper is to report on use of the electrochemical microcell technique and the scanning vibrating electrode technique for monitoring pitting corrosion on the same stainless steel microstructure. First, the electrochemical behaviour of sites containing a single inclusion was investigated in order to the determine both the successive steps occurring during the inclusions activation and some key-parameters such as the onset potential for MnS dissolution and the pitting potential. Then, the local current distribution around a pitting site was monitored at open circuit potential in order to locate anodic and cathodic regions and to obtain informations on the galvanic coupling between inclusions and the matrix. This was done using a part of a modified electrochemical microcell combined with the scanning vibrating electrode technique. (C) 2004 Elsevier B.V. All rights reserved.