A novel observation of the interaction between the macroelastic stress and electrochemical corrosion of low carbon steel in 3.5 wt% NaCl solution

This paper focuses on the interaction of macroelastic stress and electrochemical corrosion of low carbon steel in 3.5 wt% NaCl solution. The electrochemical impedance spectra (EIS), corrosion current density and open circuit potential (OCP) tests were used to represent the electrochemical behavior of low carbon steel. The microplastic deformation was studied through acoustic emission (AE) techniques and surface morphology observation. The results indicated that there was non-linear relationship between the applied stress and electrochemical corrosion of low carbon steel in 3.5 wt% NaCl solution. At the beginning of macroelastic deformation, the applied mechanical energy would activate the metal surface, so the corrosive solution would more easily to cover the metal surface and become thin liquid film, then accelerate the electrochemical corrosion process. When the gradually increased stress came to a critical value, the extra mechanical energy would not only affect the surface corrosion behavior of samples, but also enhance the microplastic deformation at some local regions of metal surface even the applied stress was far below the yield strength. Usually these two processes competed with each other. The dominated process at the beginning of elastic deformation is stress accelerating corrosion, and when exceeding the critical stress, the applied energy would induce microplastic deformation.