A Study of the Initial Stages of Local Dissolution of Carbon Steel in Chloride Solution

Resumo

The simultaneous application of optical and electrochemical methods has allowed us to investigate in detail the initial stages of the local dissolution of steel in a chloride-containing solution. The incubation period, the rate of defect formation on the surface, and the rate of individual defects development have been evaluated with high precision. It has been demonstrated that the emergence and development of local defects is possible under potentials more negative than the pitting potential determined from the polarization curve. The metal dissolution rates that occur at the initial stages of pitting formation from an individual defect have been calculated. It has been established that the initial process of defect formation under anode polarization consisted of two stages. The first stage corresponds to the emergence and intense formation of the freshly formed defect and is primarily determined by electrode potential. The second stage is shown by the development of a defect that did not depend on potential.