| WANG Xin-hua,WANG Zu-quan,CHEN Ying-chun,SONG Xu-ting,XU Cheng.Effect of AC Stray Current on Corrosion and Stripping Behavior of X70 Pipeline Steel under 3PE Coating[J],47(11):142-150 |
| Effect of AC Stray Current on Corrosion and Stripping Behavior of X70 Pipeline Steel under 3PE Coating |
| Received:July 12, 2018 Revised:November 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.11.021 |
| KeyWord:AC stray current X70 pipeline steel coating delamination crevice corrosion critical current density |
| Author | Institution |
| WANG Xin-hua |
School of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing , China |
| WANG Zu-quan |
School of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing , China |
| CHEN Ying-chun |
School of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing , China |
| SONG Xu-ting |
School of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing , China |
| XU Cheng |
School of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Beijing , China |
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| Abstract: |
| The work aims to clarify the influence of stray alternating current (AC) on the corrosion under the anticorrosive coating caused by peeling and damage of buried steel pipeline corrosion coating and the mechanism of action leading to peeling of coating. COMSOL Multiphysics? simulations, AC impedance spectroscopy analysis and three-dimensional microscope were used to study the corrosion mechanism and stripping behavior of X70 high-strength pipeline steel at 3PE coating stripping under AC stray current in Golmud soil simulation solution. The protective performance of the coating was significantly reduced due to the presence of damage points and stripping areas in the coating. The stray current was unevenly distributed on the surface of X70 steel in the initial reserved stripping area, and the current density at the breakage point was significantly higher than that at the edge of the stripping area. The corrosion reaction caused by stray currents was mainly concentrated at the damage point of the coating, while the X70 steel under the reserved peeling zone showed crevice corrosion phenomenon. Corrosion pit depth at the damage point of the coating gradually became deeper as the current density increased, but when the AC current density increased from 0 A/m2 to 100 A/m2, the peeling area of the anti-corrosion coating increased significantly. After that, when the current density continued to increase, the peeling area remained basically unchanged. When the applied alternating current density was the same, the peeling area of the anti-corrosion layer increased as the peeling area of the reserved anti-corrosion layer decreased, and the maximum corrosion pit on the X70 steel sample slightly deepened. There is a critical current density in the delamination area of coatings caused by AC stray currents and such density can result in and keep maximum stripping area. When the initial stripping area of coating is smaller, corrosion and coating stripping of X70 steel caused by AC stray current are more serious. |
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