Auger Electron Spectroscopic Studies on Oxide Films of Some Austenitic Stainless Steels Available to Purchase

Auger electron spectroscopic studies on the surface film of three different austenitic stainless steels revealed that the surface composition of the film which had been formed in Ringer’s physiological solution was almost independent of the bulk composition of the alloy. The surface concentration of Mo was essentially zero for bulk Mo concentrations of 1.3 and 2.8 At%. The surface concentration of Ni was essentially zero for a bulk composition of 10 At% and may have reached a few At% for a bulk concentration of 24 At%. The surface composition of films passivated at the rest potential for 4 days in chloride solution was found to be about 10 At% Fe, 55 At% O, 35 At% Cr and was essentially independent of bulk composition of the steel. The reasons for the beneficial effect of Mo additions in increasing resistance to pitting corrosion remain unclear.