Experimental study on corrosion compatibility of laser-welded ODS steel with liquid lead lithium

The liquid lead lithium blanket is considered to be one of the most promising blanket concepts. Oxide Dispersion Strengthened (ODS) steel probably emerge as an important candidate for blanket structure material for its substantial enhancement of neutron radiation resistance and mechanical strength at high temperature. However, during the long-term operation of fusion reactor, it’s inevitable for structural material and its welded joints to experience adverse corrosion from liquid lead lithium. In this paper, the self-developed rotating corrosion apparatus was used to conduct a corrosion test of laser-welded ODS steel exposed to liquid lead lithium for thousands of hours. The influence of corrosion time on the corrosion of ODS steel laser welding was analyzed. The results show that the corrosion rates of ODS steel and its welded joints are 76 and 88.6 μm⋅year -1 , respectively. After 5000 h of exposure, various pits and gullies are observed on the surface of weld zone, while penetrating cracks are clearly visible in the cross-section. Corrosion occurs preferentially from austenite grain boundaries, and the corrosion mechanism is mainly the dissolution of Fe and Cr alloying elements. Meanwhile, a decrease in the hardness of the welded joints with the increase of corrosion time is observed.