Evaluation of Corrosion Phenomena of T91 Steel in Stagnant Liquid Lead at High Operational Temperatures

The present study aims to deepen the knowledge on the corrosion behavior of martensitic T91 steel in contact with liquid lead in view of its application in advanced nuclear energy systems. Steel samples have been analyzed after the immersion in stagnant molten lead at different temperatures (550°C to 650°C) and for an exposure time of 550 h. In order to evaluate the influence of different oxidizing conditions, the corrosion tests were performed under both Ar and Ar-H2 mixtures. Within the temperature range applied, the oxygen content in the liquid lead was Co = 6.8±2.7 × 10−2 wt% and Co = 9.2±3.6 × 10−8 wt%, respectively. When the Ar atmosphere was applied, dissolution of iron and chromium has been observed for temperature above 590°C. Conversely, under an Ar-H2 mixture atmosphere, mainly the presence of internal oxidation along the grain boundaries whose depth increases with temperature was detected.