Research on Corrosion Behavior of X80 Steel Under HVDC Interference

In recent years, with the large-scale construction of High Voltage Direct Current (HVDC) power transmission projects, more and more buried pipelines are affected by the interference of the current flowing into the ground by the grounding pole. Field tests show that HVDC interference causes a large shift of pipeline ground potential. How to accurately understand the law of HVDC interference and the effect of corrosion is the urgent need of actual production. In order to accurately understand the corrosion effect of HVDC interference on buried metal pipelines, this paper explores the relationship between conditions such as interference potential, coating defect shape and soil environment and the corrosion behavior of X80 steel. The results show that: 1) When the interference voltage is applied from 10 to 300 V for 1 hour, the corrosion rate is the highest when the interference voltage is 200 V, and the corrosion rate is 46.26 mm/h. At the same time, this result also conforms to Faraday's law. 2) The corrosion rate increases with the increase of the aspect ratio. The maximum is reached at an aspect ratio of 7:1, which is 10.72 mm/h. 3) When the interference voltage is 100 V, the corrosion rate of the specimen in clay is the fastest, which is $36.05\ \mu\mathrm{m}/\mathrm{h}$ . The corrosion rate of the specimen is related to the soil resistivity, and the lower the soil resistivity, the higher the corrosion rate of the specimen.