Effect of anodic dissolution and passivation on X80 steel in NaHCO3 solution

Abstract

The effects of extreme stray current on the anodic dissolution and passivation of X80 steel in NaHCO3 solution were investigated using measurements of polarization curves and EIS, AFM and SEM techniques. Under the interference of anodic current (i = 0~200 A/m2), main constituents of corrosion products of X80 steel were FeO(OH) and Fe3O4. A double-layer film formed at i = 100 A/m2, in which FeOOH was in outer and Fe3O4 lied in inner. The formation mechanism of Fe3O4 was confirmed and described by the electrochemical reaction in various regions on anodic potentiodynamic polarization curve.