The corrosion resistance and passive film compositions of 12% Cr and 15% Cr oxide dispersion strengthened steels in nitric acid media

• Corrosion resistance of oxide dispersion strengthened (ODS) steels is evaluated.
• 12% Cr ODS steel exhibited high corrosion rate in boiling 3 M to 9 M HNO3.
• Increasing concentration of nitric acid increases corrosion rate in both ODS steels.
• Lower corrosion rate of 15% Cr ODS steel in HNO3 was attributed to the role of Al.
• The formation of Y–Ti–O and Y–Hf–O oxides may suppress intergranular corrosion.

The passive film compositions and corrosion resistance of 12% Cr and 15% Cr oxide dispersion strengthened (ODS) steels in 3 M HNO3 to 9 M HNO3 was evaluated. The potentiodynamic polarization plots exhibited a shift in corrosion potential, and higher passive current density with increasing HNO3 concentrations. In 12% Cr ODS steel, high corrosion rate was observed in all HNO3 concentrations. However, low corrosion rate observed in 15% Cr ODS steel was attributed to Al2O3 enrichment. The TEM analysis indicated a complex Y2Hf2O7 formation in 15% Cr ODS steel, and this may have a role in suppressing intergranular corrosion attack.