Long-term immersion tests of engineered materials in the Tono mine; Results for metals

Hama, Katsuhiro ; Taniguchi, Naoki ; Honda, Akira

The burial tests of mild steel and pure titanium were performed in a gallery at Tono mine to assess the corrosion resistance of these materials under goundwater environment. Specimens were placed in the container and immersed into groundwater. After the immersion period, the apperance of the surface of these specimens were observed. The corrosion product of mild steel specimen was analysed by various methods. The average corrosion rate of mild steel for 10 years was assessed by the measurement of the weight loss of carbon steel specimen. The results of the test were summerised as follows : (1)The average corrosion rate of mild steel for 10 years was assessed to be 4.36 10mm/y by the weight loss of the specimen. (2)The corrosion product consists of outer porous substance and inner tight corrosion product film. The former contains ferric oxide such as goethite and the latter contains ferrous oxide such as magnetite. (3)The evidence of the initiation of localised corrosion was not observed on the titanium specimens.