Erosion-corrosion of RAFM JLF-1 steel in Lithium flow induced by impeller
The purpose of the present study is to investigate erosion-corrosion characteristics of reduced activation ferritic martensitic steel, JLF-1 (Fe-9Cr-2W) in flowing Li. The erosion-corrosion characteristics were investigated by means of corrosion tests with rectangular plate type specimen of JLF-1 in Li stirring pot, where the Li flow was induced by impeller in the pot. The test temperature was 500 C and 600 C, and there was no temperature difference in the Li stirring pot. The erosion-corrosion characteristics were evaluated by the weight loss measurement of the specimens and metallurgical analysis for the corroded surface. The results were compared with those obtained from the tests at static condition to feature the effect of Li flow on the corrosion. The weight loss of the specimens tested in Li flow was larger than that tested in the static tests. The corroded surface showed the local corrosion along lath boundary and grain boundary of JLF-1 as the same as that after the test at static condition. There were defects which were not observed in the specimen tested at the static condition. The defects were the trace of the erosion-corrosion. The corrosion attack to the boundaries made weak bonding between the subgrains, and the subgrains were peeled from the surface by the Li flow.
The Investigation of Corrosion Behaviors of Type 316L Stainless Steel in Stagnating Liquid Lithium
Abstract The corrosion behavior of Type 316L stainless steel in stagnating liquid Li under an elevated-temperature environment was investigated using a scanning electron microscope and an energy dispersive X-ray detector and self-designed laser-induced breakdown spectroscopy. A nonuniform and cell-like branched structure separated by distinct boundaries was observed, and a porous and rugged corroded layer was formed on the surface of the substrate after 500 h exposing 350°C liquid Li. This showed that the intensity of the Cr element on the superficial corroded sample decreased significantly when the depth reached ~2.8 μm and then was gradually restored in the range of ~5.6 μm. Meanwhile, the intensity of the Li element revealed consistent reduction to zero at ~4.0 μm. This study disclosed element transfer and penetration along a depth in the corrosion process between the liquid lithium and steel matrix.
Overview of materials research for fusion reactors
Materials research for fusion reactors is overviewed from Japanese, EU and US perspectives. Emphasis is placed on programs and strategies for developing blanket structural materials, and recent highlights in research and development for reduced activation ferritic martensitic steels, vanadium alloys and SiC/SiC composites, and in mechanistic experimental and modeling studies. The common critical issue for the candidate materials is the effect of irradiation with helium production. For the qualification of materials up to the full lifetime of a DEMO and Power Plant reactors, an intense neutron source with relevant fusion neutron spectra is crucial. Elaborate use of the presently available irradiation devices will facilitate efficient and sound materials development within the required time scale.