Corrosion characteristics of RAFM steels and unalloyed metals in static Pb-17Li

The corrosion characteristics of reduced activation ferritic martensitic steels, JLF-1 (Fe-9Cr-1.94W-0.09C) and 9Cr-ODS (Fe-9Cr-1.97W-0.14C-0.29Y-0.23Ti), and unalloyed metals of Cr, W and Mo in liquid Pb-17Li were investigated by means of static corrosion tests at 600degC for 500 hours. The corrosion of the JLF-1 steel was based on the dissolution of Fe and Cr from the steel surfaces in the Pb-17Li. The dissolution type corrosion of the 9Cr-ODS steel was based on the strong depletion of Cr, W and O at the steel surface. The corrosion of the unalloyed Cr specimen in the Pb-17Li was much larger than that based on the Cr solubility in the Pb-17Li when a Mo crucible was used in the corrosion test. The corrosion was promoted under an unsaturated condition because the wetted surface of the Mo crucible trapped the dissolved Cr in the Pb-17Li by the alloying process. The dissolution of Mo in the Pb-17Li was also promoted by the alloying with the dissolved Cr though the solubility of Mo in the Pb-17Li was quite low. The weight loss of the unalloyed W specimen exposed in the Pb-17Li was larger than that estimated from the solubility in the Pb-17Li. Some oxide particles were detected on the surface of the W specimen. The reasonable mechanism on the large weight loss of the W specimen was the formation and detachment of the oxide particles in the Pb-17Li. (author)