Electrochemical Behavior of X80 Steel in Simulated Soil Solutions with High pH at Different Temperatures

The electrochemical behavior of X80 steel in simulated soil solutions with hjgh pH (0.5 mol·L-1Na2CO3+1.0 mol·L-1NaHCO3) at different temperatures (25 ℃, 45 ℃and 65 ℃) was investigated by potentiodynamic polarization, metallurgical microscopy and electrochemiscal impedance spectroscopy(EIS).The results of potentiodynamic polarization and metallurgical microscopy showed that the corrosion resistance of the steel and its passive films were weakened gradually as the temperature increasesd, and the worst condition was at 65 ℃. All electrochemical impedance spectroscopy(EIS) of passive films at different temperatures showed the characters of double capacitive arcs and Warburg impedance. As the temperature increased, the compactness of passive films on X80 steel surface became worse and thus the protection of passive film for X80 was weakened gradually.