Effect of Polarization on Corrosion Behavior of X70 Steel in NaCl Solution

The effect of polarization on the corrosion behavior of X70 steel in the solution containing different concentrations of NaCl was studied by electrochemical tests and corrosion morphology observation. The results showed that the self-corrosion current density and corrosion rate of the ploarized sample were higher than those of the unpolarized sample in 1.5% NaCl solution. Ferrous oxides formed in the corrosion layer under the action of polarization were involved in the cathodic reaction, which accelerated the cathodic reduction process and the corrosion of the sample. In NaCl solution of various concentrations, during the initial stage of polarization, the critical corrosion concentration was 3.5%. In the later stage of polarization, the greater the concentration of NaCl, the less the corrosion tendency and the corrosion rate.