A comparative study on corrosion kinetic parameter estimation methods for the early stage corrosion of Q345B steel in 3.5wt% NaCl solution

Corrosion kinetic parameters play an important role in researchers' ability to understand and predict corrosion behavior. The corrosion kinetic parameters of structural steel Q345B specimens immersed in 3.5wt% NaCl solution for 1-2 h were determined using linear polarization resistance (LPR), Tafel-curve multiparameter fitting, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) methods. The advantages and disadvantages of each method were investigated and discussed through comparative investigation. Meanwhile, the average corrosion rate was examined using traditional coupon tests. The results showed that the corrosion current density values estimated by EFM at a base frequency of 0.001 Hz and those obtained by Tafel-curve four-parameter fitting (TC4) are similar and consistent with the results of coupon tests. Because of their slight perturbation of the corrosion system, EIS and EFM/TC4 in collaborative application are the recommended techniques for determining the kinetics and the corresponding parameters for the homogeneous corrosion of the naked metal. In our study of the electrochemical kinetics, we obtained much more abundant and accurate electrochemical kinetic parameters through the combined use of different electrochemical methods.