The Electrochemical Behavior of 15-5PH Stainless Steel in Acidic Solutions

In this paper, the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) of 15-5PH stainless steel were measured in the 0.5M Na2SO4 acid solution with various pH values and Cl- concentrations. The characteristics of surface passive film formed under different corrosive conditions were analyzed using X-ray photoelectron spectroscopy (XPS). It is found that all the polarization curves of 15-5PH steel present passivity in the testing acid solution, and the corrosion current density change from 16.032 mu A to 1.967 mu A with the pH value increasing between 1and 5. In contrast to the current performance, the impedance changed oppositely. With addition of Cl- the pits initiated on the steel electrode and the pitting potential was reduced by increasing concentration of Cl-. Moreover, the oxides and hydroxides of Fe, Cr, Ni and Cu are the primary components of the passive film.