Corrosion of low-carbon cast steel in concentrated synthetic groundwater at 80 to 150°C

Corrosion properties of American Society for Testing and Materials (ASTM) A216-Grade WCA low-carbon steel were evaluated in concentrated synthetic groundwater at 80 to 150°C. The evaluation provides information on the use of the steel as a container material in the proposed Yucca Mountain high-level waste repository. Uniform corrosion rates measured over 4 months ranged from 10 to 40 μm/year, in initially aerated static solutions under gamma irradiation at 1.3 × 106 rad/h. Irradiation effects on uniform corrosion rates were not discernible after 4 months. Pitting corrosion was also found, but the pitting factor was small. Microstructural effects on corrosion were not significant. During corrosion under irradiation, there was an indication of a large amount of hydrogen absorption in the steel. Constant extension rate tests showed evidence for environmental assisted cracking under free corrosion conditions, and strong evidence of hydrogen embrittlement and moisture-induced ductility loss. The use of the test results in support of the Yucca Mountain project is discussed.