An electrochemical study on the effect of stabilization and sensitization heat treatments on the intergranular corrosion behaviour of AISI 321H austenitic stainless steel

摘要

The intergranular corrosion behavior of AISI 321H stainless steel was investigated using oxalic acid etching, double-loop electrochemical potentiokinetic reactivation, anodic polarization, Mott-Schottky, electrochemical impedance spectroscopy, X-ray diffraction, optical microscopy and scanning electron microscopy techniques. The results showed that stabilized samples that are sensitized for less duration have more intact passive films and are more resistant to intergranular corrosion than the others. In addition, stabilization heat treatment cannot prevent intergranular attack when sensitization time is high. Finally, it was observed that by increasing the applied voltage in the transpassive region, the corrosion mechanism changes from uniform type to severe localized attack.