Abstract
The corrosion behaviour of a carbon steel weld joint under anaerobic conditions was investigated to estimate the long term integrity of the carbon steel overpack. The welded specimens in this study were prepared using three different welding methods: gas tungsten arc welding, gas metal arc welding and electron beam welding. General corrosion was observed for each immersion specimen, and the corrosion rate at the weld joint was the same as or less than that of the base metal. The concentration of hydrogen that absorbed during immersion testing was <2·48×10−5 mol kg[Fe]−1 (0·05 ppm) after 3 years, a value regarded as having little influence on hydrogen embrittlement. The susceptibility to hydrogen embrittlement was the highest in the base metal, suggesting that there was little adverse effect on the weld joint from welding. The welded carbon steel overpack is assumed to maintain its resistance to corrosion as a disposal container for the expected lifetime under anaerobic underground conditions.
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