Corrosion resistance of 15–15Ti and 316Ti austenitic steels as fuel cladding in liquid lead-bismuth eutectic at 550 ℃: The dominant role of grain structure

The corrosion mechanism of 15–15Ti and 316Ti austenitic stainless steels exposed to liquid lead-bismuth eutectic (LBE) at 550 ℃ with dissolved oxygen 5 × 10−7 mass% was investigated. The oxides formed on steels have a dual- or triplex-layered structure. The higher content of Cr in oxides, the better inhibiting effect on Ni diffusion. The local dissolution attack left a Ni-rich recrystallization area with fcc-phase fine grains. The preferential intergranular oxidation (PIO) in random GBs of 15–15Ti induced intergranular cracking while the annealing twin boundaries were more resistant to crack. The 316Ti with smaller grains presented higher resistance to corrosion and intergranular cracking.