CREVICE CORROSION OF LOW ALLOY STEEL ANDCARBON STEEL IN THE SIMULATED GROUNDWATER AT 90 ℃

Carbon steel and low alloy steel as candidates of high-level radioactive waste packaging materials, will undergo groundwater corrosion during long term disposal in underground repository, so it is necessary to study the corrosion behaviors of carbon steel and low alloy steel in the specific environment. Crevice corrosion behaviors of carbon steel Q235 and low alloy weathering steel Corten A were studied in a simulated groundwater at 90 C through immersion tests and electrochemical measurements. SEM, EDS and Raman spectra were employed to analyze the corrosion product scales. The results show that both steels occured crevice corrosion and the crevice corrosion depth increased with corrosion time. Corten A underwent more serious crevice corrosion than Q235. In neutral or acidic solution, the corrosion resistance of Corten A was superior to Q235, but when the pH value of the solution was lower than 1, Corten A exhibited lower corrosion resistance than Q235. The alloying elements Cr, Cu and Si in Corten A were harmful to the resistance to crevice corrosion in the solution.