Comparison of the corrosion behaviour of 10Cr and 17Cr Al added ODS steel in simulated reprocessing nitric acid medium

• Published in: Journal of nuclear materials Vol. 599; p. 155258
• Main Authors: D, Shakthi Balan, Priya, R., Thinaharan, C., Sakairi, M., Ukai, S., Ningshen, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2024
• Subjects: Nitric acid corrosion; Nuclear fuel reprocessing; ODS steel; Oxidizing ions; ODS steel; Nitric acid corrosion; Oxidizing ions; Nuclear fuel reprocessing
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2024.155258

•Spontaneous passivation exhibited for both 10Cr and 17Cr Al-ODS steel in HNO3.•The ennoblement of corrosion potential is larger in low Cr Al-ODS steel.•Low Cr Al-ODS steel revealed a higher anodic and cathodic reaction rate in HNO3.•Enrichment of Al2O3 due to a synergistic effect of low Cr in 10Cr Al-ODS steel.•The higher corrosion resistance of 17Cr Al-ODS steel is attributed to higher Cr and Cr2O3 formation. It is imperative to comprehend the corrosion behavior of different Cr containing Al-added ODS steel reactor clad materials in nuclear reprocessing simulating conditions, as high dissolution of clad material is not desirable. In this present work, the effect of varying HNO3 concentrations (3, 6, 11.5 M HNO3) and with oxidizing (Cr6+, Ce3+) and non-oxidizing (Fe3+) ions in 6 M HNO3 on 10Cr (10Cr-5Al-0.5Ti-0.5Y2O3-Fe) and 17Cr (16.78Cr-4.46Al-0.5Ti-0.45Y2O3-Fe) Al-ODS steels are investigated. The potentiodynamic anodic polarization studies revealed an ennoblement of corrosion potential by elevated cathodic current resulting from increased oxidizing conditions in HNO3 by concentration and oxidizing ions. Through various electrochemical techniques like open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), the 17Cr Al-ODS steel exhibited improved corrosion resistance with lower Ecorr, increased passivation range (Epass range), lower corrosion current density (icorr) and increased charge transfer resistance (Rct). The SEM studies revealed variation in corrosion morphology as shallow corrosion cavities and deeper corrosion pits in 17Cr Al-ODS and 10Cr Al-ODS steel, respectively, at high oxidizing environment. The enhanced corrosion resistance of 17Cr Al-ODS is associated to the improved passivation with the high Cr level in the steel compared to 10Cr-ODS steel, which is corroborated by XPS analysis. New knowledge on nitric acid corrosion mechanism on the Cr in Al-ODS steels and the influences of oxidizing ions in reprocessing environments are described. [Display omitted]