2020•Zhongguo fushi yu fanghu xuebaoRequires access
Effect of Applied Potential on Stress Corrosion Behavior of X80 Pipeline Steel and Its Weld Joint in a Simulated Liquor of Soil at Lunnan Area of Xinjiang
Zhu Lixia, Jia Haidong, Luo Jinheng, Lifeng Li, Jian Jin, Gang Wu, XU Cong-min, Equipment Materials
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Abstract
The stress corrosion cracking(SCC) behavior of X80 pipeline steel and its weld joint in a simulated liquor of soil at Lunnan area of Xinjiang was studied by means of slow strain rate tensile tests(SSRT), SEM observation and potentiodynamic polarization tests. The results showed that both the X80 pipeline steel and its weld joint have obvious SCC susceptibilities, and the mode of fracture cracking propagation is transgranular cracking(TGSCC) under different applied potentials, and the SCC susceptibility of the weld seam is higher than that of the base metal under the same applied potential. SCC susceptibility and mechanism would vary with the applied potential. At-500 mV, the SCC of both X80 steel and its weld joint may be ascribed to the synergistic action of the anodic dissolution(AD) at crack tip and the rupture of passivation film. The SCC susceptibility of X80 pipeline steel increased markedly for potentials below-800 mV(-850,-1000 and-1500 mV) due to a strong hydrogen embrittlement(HE) effect on SCC process and hydrogen induced cracking promoted by cathodic hydrogen evolution reaction.