Effect of solution pH, Cl− concentration and temperature on electrochemical behavior of PH13-8Mo steel in acidic environments

The effect of solution pH, Cl− concentration and temperature on the electrochemical corrosion behavior of PH13-8Mo steel in acidic solution was investigated by using the electrochemical tests, scanning electron microscopy and X-ray photoelectron spectroscopy. The PH13-8Mo martensitic precipitation hardened stainless steel is in the passivity state when the pH value is above 3.0, below which the anodic polarization curves of the steel are actively dissolved. The corrosion current density gradually decreases with increasing the solution pH and decreasing Cl− concentration and solution temperature. Pits are initiated on the sample surface in the presence of the Cl− and gradually developed into uniform corrosion with increasing the Cl− concentrations. Moreover, the corrosion is more serious with an increase in solution temperature.