Abstract: The stress corrosion cracking(SCC) behavior of U-bent specimens of Q235 and X70 steels buried in Singapore soil are investigated by observation of morphology involving pitting and cracking, analysis of corrosion products, as well as physical and chemical properties of soil, a preliminary study the corrosion behavior of X70 and Q235 steels made in China in a typical foreign soil environment. It is found that Singapore soil contains more sulfide bacteria, the sulfide bacteria reducing the damaging effects of sulfate reducing bacteria. Q235 and X70 steels are sensitive to SCC in acid soil environment of Singapore, the SCC susceptibility of X70 steel is higher than that of Q235 steel and the strength of steels affect the SCC susceptibility; pitting and acidity of soil promote the occurrence of SCC, the SCC process is mainly controlled by anodic dissolution(AD), while there also may by hybrid controlled by hydrogen induced cracking(HIC).

Key words: acidic soil, Q235 steel, soil corrosion, stress corrosion cracking(SCC), X70 steel