CORROSION BEHAVIOR OF X80 STEEL IN YINGTAN SOIL SIMULATED SOLUTION UNDER DISBONDED COATING
ZHAO Bo 1,2, DU Cuiwei 1,2, LIU Zhiyong 1,2, LI Xiaogang 1,2, YANG Jike 1,2, LI Yueqiang 1,2
1. Corrosion and Protection Center, University of Science and Technology Beijing, Beijing 100083
2. MOE Key Laboratory of Corrosion and Protection, University of Science and Technology Beijing, Beijing 100083
Cite this article:
ZHAO Bo DU Cuiwei LIU Zhiyong LI Xiaogang YANG Jike LI Yueqiang. CORROSION BEHAVIOR OF X80 STEEL IN YINGTAN SOIL SIMULATED SOLUTION UNDER DISBONDED COATING. Acta Metall Sin, 2012, 48(12): 1530-1536.
In this work, a rectangular crevice disbanded coating model of buried steel pipeline in Yingtan soil simulated solution was made, and the in situ electrochemical measurement of electrochemical impedance spectroscopy (EIS) was used for characterization of X80 steel under the disbonded coating, at the same time, the corrosion behavior was also investigated. The results showed that the electrochemical characteristics in each position of disbonded area was almost same in the early corrosion time, and the EIS was composed of high–frequency capacitance and low–frequency inductance. After corrosion occurred, the high–frequency capacitance radius increased, and the low–frequency inductance disappeared. The extent of corrosion of X80 steel specimen surface was rather distinct with distance from holiday. The corrosion at holiday and the bottom of disbonded area was most serious because of oxygen corrosion and anodic dissolution. However, in the central, it was weaker. After removing the corrosion product, pits appeared obviously on the specimen surface in the central of disbonded area,indicating that the tendency of pitting occurring increased, and the type of corrosion changed from general corrosion to localized corrosion. According to the EIS and experimental results, the corrosion process under disbanded area could be divided into three steps: oxygen depletion, anion migration and corrosion expansion.
Supported by National Natural Science Foundation of China (Nos.51131001 and 50971016) and Fundamental Research Funds for the Central Universities (No.FRF–TP–09–029B)
