Morphological and compositional features of corrosion behavior of SUS410-SUS410, SUS316-SUS316 and SUS410-SUS316 TIG welded joints in Li

摘要

The corrosion behavior of SUS410-SUS410, SUS316-SUS316, SUS410-SUS316 tungsten inert gas welded joints in static Li at 600 C for 250 h was investigated as applied for lithium-cooled systems of fusion reactor. The different regions of welded joints (base metal, weld metal, heat affected zone, fusion layer) possessed by the same phase state (ferrite or austenite) showed no substantial difference in the corrosion behavior under the given conditions of test. The corrosion attack resulted in the marked depletion of corresponded near-surface layers with chromium and nickel. The clear corrosion induced refining of surface grain structure, in comparison with initial surface morphology (polished) and corresponded bulk grain size, was observed indicating about the prevalence of the grain boundary corrosion attack during which the low-angle sub-boundaries transform into the large-angle due to the increase in their defectiveness.