Effect of pH Value on Stress Corrosion Cracking of X70 Pipeline Steel in Acidic Soil Environment
来源期刊：Acta Metallurgica Sinica2013年第4期
论文作者：Zhiyong LIU Cuiwei DU Xin ZHANG Fuming WANG Xiaogang LI
文章页码：489 - 496
摘 要：The effect of pH value on the stress corrosion cracking（SCC） of API X70 pipeline steel in simulated acidic soil solutions was investigated by using slow strain rate test,electrochemical polarization curves,electrochemical impedance spectroscopy,and scanning electron microscopy.pH plays an important role in the susceptibility and electrochemical mechanism of SCC.The pH higher than 5 has no significant effect on electrochemical processes.By contrast,the pH lower than 5 intensifies cathodic hydrogen evolution reactions,thus increasing the cathodic current and corrosion potential.Under different pH values,the SCC mechanism of X70 pipeline steel varies among anodic dissolution（AD）,hydrogen embrittlement（HE）,and the combination of AD and HE（AD + HE） with variations of applied potential.At-850 mV SCE,the SCC mechanism is HE if pH is less than 4 or AD + HE if pH value is more positive.
Zhiyong LIU1,2，Cuiwei DU1，Xin ZHANG3，Fuming WANG3，Xiaogang LI1
1. Corrosion and Protection Center,University of Science and Technology Beijing2. School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing3. Nuclear and Radiation Safety Center,Ministry of Environmental Protection of China
摘 要：The effect of pH value on the stress corrosion cracking（SCC） of API X70 pipeline steel in simulated acidic soil solutions was investigated by using slow strain rate test,electrochemical polarization curves,electrochemical impedance spectroscopy,and scanning electron microscopy.pH plays an important role in the susceptibility and electrochemical mechanism of SCC.The pH higher than 5 has no significant effect on electrochemical processes.By contrast,the pH lower than 5 intensifies cathodic hydrogen evolution reactions,thus increasing the cathodic current and corrosion potential.Under different pH values,the SCC mechanism of X70 pipeline steel varies among anodic dissolution（AD）,hydrogen embrittlement（HE）,and the combination of AD and HE（AD + HE） with variations of applied potential.At-850 mV SCE,the SCC mechanism is HE if pH is less than 4 or AD + HE if pH value is more positive.
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