The Electrochemical Behavior and Characteristics of Passive Film on 2205 Duplex Stainless Steel Under Various Hydrogen Charging Conditions

The electrochemical behavior and the characteristic of 2205 duplex stainless steel (UNS S32205) under various hydrogen charging conditions in borate buffer solution containing chloride ion were evaluated by potentiodynamic measurements, electrochemical impedance spectroscopy, capacitance measurements (Mott-Schottky approach), and anodic polarization experiments. The results indicate that the hydrogen generated by the cathodic charging process decreased the corrosion resistance of 2205 duplex stainless steel, especially the pitting resistance of passive film. As a result of the hydrogen charging, the semiconductor characteristic of the passive film changed from n-type and p-type coexisting to only n-type existing, and the pitting susceptibility increased. Along with the charging process, the critical concentration of chloride for breakdown of passive film decreased and the repassivation process was prevented by hydrogen.