Corrosion behavior of X80 steel under disbond coating interfered with AC
Anti-Corrosion Methods and Materials
ISSN: 0003-5599
Article publication date: 3 September 2019
Issue publication date: 17 October 2019
Abstract
Purpose
This paper aims to research the corrosion behavior of the metal under the disbonded coatings interfered with AC through electrochemical method.
Design/methodology/approach
The corrosion behavior of the metal under disbond coating interfered with alternate stray current (AC) was studied by electrochemical methods using the rectangular coating disbonded simulator. The obtained data from electrode potential test, electrochemical impedance spectroscopy (EIS) and polarization curves in simulated soil solution indicated that under the natural corrosion condition, the self-corrosion potential and the corrosion current density of the metal at different depths under disbond coating had obviously changed if there was AC interference.
Findings
The self-corrosion potential of the metal at the same depths under disbond coating shifted negatively with the rising of the AC voltage. Under the condition of cathode polarization, there was still obvious potential gradient with the extension of the deep peeling of the coating gap, and the corrosion current density of the test points was minimum, and the protection effect was best when the cathode protection potential was −1.0 V. When the metal was applied with over-protection, the corrosion rate of the metal increased as AC stray current flowing through it increased.
Originality/value
This paper used the rectangular aperture device to study the corrosion behavior of X80 steel under the disbonded coatings through electrochemical methods when the AC stray current interference voltage was 0V, 1V, 5V or 10V and the protection potential was 0V, −0.9V, −1.0V, −1.2V or −1.3V, respectively. There is great significance to the safe operation and long-term service of pipeline steel in soil environment.
Keywords
Acknowledgements
Our research work was supported by “the Opening Fund of Shandong Key Laboratory of Oil & Gas Storage and Transportation Safety” and “the Fundamental Research Funds for the Central Universities (19CX05007A)”.
Conflict of interests: The authors declare that there is no conflict of interests regarding the publication of this article.
Citation
Ding, Q., Li, Z., Shen, T. and Cui, G. (2019), "Corrosion behavior of X80 steel under disbond coating interfered with AC", Anti-Corrosion Methods and Materials, Vol. 66 No. 6, pp. 704-718. https://doi.org/10.1108/ACMM-12-2017-1879
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited