Properties of the passive films on cold worked stainless steels in conditions of susceptibility to stress corrosion cracking

Passive films, formed on annealed and cold worked AISI 304 stainless steel in hot chloride media, were examined using polarization resistance and impedance measurements. The obtained results show the influence of cold work on film conductivity, which can be correlated to conditions of susceptibility to stress corrosion cracking. Capacitance measurements, using the Mott-Schottky approach, revealed that a change from n to p type semi-conductivity is associated to susceptible conditions with an increase in the doping density estimated for cold worked samples in the presence of chloride. It is assumed that p-type semi-conductivity of the passive film together with the position of the flat band potential has a strong influence on the dissolution processes at the corrosion potential. Based on this analysis the influence of plastic deformation, at the dislocation scale, is discussed. (authors)