Corrosion of stainless PM tool steels Interpretation of current density potential curves in acid environments

For testing the corrosion resistance of metallic materials, the measurement of current density potential curves in acid environments e. g. sulphuric acid is a widely used method. These curves are usually evaluated by means of the current density in the passive area, the maximum current density in the active peak and the width of the passive area. Stainless cold work tool steels however feature a more complex behavior which pushes this approach to a limit. Thus, a more detailed evaluation is necessary to understand the current density potential curves of such multiphase- materials. In this paper the relation of the curve progression and corrosion phenomena on the microscopic scale were investigated in order to contribute to a better understanding of experimental data.