CATHODIC PROCESSES ON CORRODING LOW-CARBON STEEL - THE EFFECT OF THE DEGREE OF DEFORMATION

The influence of the degree of deformation of low-carbon steel (0.48% Mn, 0.47% Si, 0.085% C) caused by mono-axial stretching was investigated with respect to the kinetics of electrochemical hydrogen evolution and the reduction of oxygen and hydrogen peroxide on the electrode surface. In 0.5 M H2SO4 deformation of the metal decreased the cathodic hydrogen evolution reaction rate by half compared to the annealed sample. In weakly alkaline borate buffer (pH 9.8) neither the oxygen nor hydrogen peroxide reduction rates were influenced by deformation, while in chloride solutions the effect was similar to that for hydrogen evolution. This indicates that the reduction of both oxygen and peroxide take place at the passive film-solution interface which is not influenced by bulk metal deformations, while for reactions occurring at the metal-solution interface changes of structure, induced by deformation, inhibit the cathodic processes to a small degree.