Effect of cold deformation on the electrochemical behaviour of 304L stainless steel in contaminated sulfuric acid environment

The effect of cold deformation on the microstructure and electrochemical corrosion behaviour of 304L stainless steel in contaminated sulfuric acid solutions (simulated proton exchange membrane fuel cells environments) were evaluated using electron backscatter diffraction analyses, electrochemical measurements, and surface analyses. The internal microstructure,including the grain sizes, angles of the grain boundaries, low coincidence site lattice boundaries, and phase transformations, was changed due to the cold deformation. No noticeable modifications of the pitting corrosion potential were observed during the various deformations, except for a slight enhancement in the passive current density with an increase in the deformation. The CrO ₃ and metal Ni species in the passive film were investigated after deformation. After heavy deformation (greater than 60%), nickel oxides were detected. Moreover, the Cr/Fe and O ²⁻ /OH ⁻ ratios in the passive film were higher before deformation, and they decreased with an increase in the deformation level.