Electrochemical Behavior of X70 Steel Corrosion in Sand with Direct Current

The effects of electrifying time of direct current on the corrosion behavior of X70 steel in sands and the corrosion mechanism were investigated according to the polarization curves and electrochemical impedance spectroscopy. The results show that direct current accelerated the corrosion of X70 steel and the greater the corrosion rate, the longer the electrifying time. The corrosion potential experienced a positive-negative-positive process with the electrifying process, indicating that sandy soil pore water, oxygen-containing substances and corrosive ions were all involved in the electrode reaction. Based on the results of impedance spectroscopy, the number of time constant of impedance spectroscopy increased from two to three then passed into two, the corrosion process experienced appearing and disappearing of the inductive arc.