Corrosion Behaviour of Low Alloy Steel TIG Weldment in Simulated Groundwater

摘要

A safe and reliable method to dispose the high-level radioactive waste is geological disposal with the waste sealed in waste packaging containers, presently. Container material selections are mostly alloys. During the long term geological disposal, the greatest threat to the packaging container is corrosion caused by groundwater which may appears in some disposal repositories. Previous research shows that the welded joint, as a special area formed during the process of the containers, is more likely to be subjected to corrosion. This paper investigates the general corrosion and crevice corrosion behavior of the welding joints of E355CC in a simulated groundwater reference to BeiShan groundwater. The welding joints were fabricated by Tungsten Inert Gas Arc Welding method. Scanning Electron Microscopy, Contour-graph were used to characterize the corroded samples. The welded joints were immersed in the simulated groundwater with different temperatures and oxygen concentrations for 6 months. The result shows that crevice corrosion does not occur on the welding joint of E355CC at room temperature. The most prone to corrosion is the Heat Affected Zone. At room temperature, the difference of corrosion rates between three regions becomes more apparent when the crevice present. .Local corrosion occurs on the welding joint at 90°C. There is no significant different between different zones.