Contact corrosion of steel 3 caused by its different aeration or chloride concentration conditions

Corrosion processes caused by a contact of metal samples with initially different potentials were studied with specially designed electrochemical simulator. Probable corrosion cells were determined for carbon and low-alloyed steels. It is shown that irrespective of factors causing the initial potential difference between the samples in contact, the corrosion type and rate are determined by their potentials settled upon the contact and referred to the corresponding anodic polarization curve. Any current measured in the external circuit corresponds to a difference in the dissolution rates of surface areas in contact rather than to the metal dissolution rate. A local corrosion of phase-heterogeneous carbon, as well as low-alloyed, steels at their active dissolution rates of their phase components at the corresponding potential.