Electrochemical and Microscopy Study of Localized Corrosion on a Sensitized Stainless Steel AISI 304

Abstract

Corrosion has been frequently recognized as failure's root cause for diverse engineering components like those associated to production lines, like in boiling water reactor piping systems (1). It is important that several electrochemical techniques help conjointly to elucidate some of the corrosion specificities, like localized corrosion of traditional materials. Pitting corrosion has been usually reported to affect stainless steels because it engages more frequent than not, second phase particles that precipitate out at the matrix and the grain boundary network, thereby consuming alloying elements that, for example, participate on sustaining passivity. Thermally-dependent fabrication operations such as welding bring about sensitization, particularly within the 450 to 700 ºC range. Exposure propitiates nucleation and growth of chromium carbide networks: this makes the boundaries and neighboring areas sensitive to depletion. Thus the precipitates are directly suspect of significant decrements in protective potential as the chromium has been chemically bound to carbon, thereby decreasing the surface passivating abilities. Therefore, the present work reports the electrochemical and microscopy results obtained after immersing the heat treated SS304 samples for diverse periods in a suitable electrolyte to studying their potentiodynamic polarization and EIS behaviors.