Anodic Corrosion Failure Behavior of Magnesium Alloy in Drainage Ground Bed under Dynamic DC Interference

The corrosion of sacrificial anode material under stray current interference affects the current output and drainage performance of the anode. The periodic DC interference was used to simulate the dynamic DC interference of the subway. A constant current DC interference of 5 A/m² was applied every 300 seconds for 100 seconds. The corrosion behavior and failure law of the magnesium alloy anode ground under dynamic DC interference were studied through electrochemical measurement, corrosion morphology observation, corrosion product analysis, and weight loss test methods. The results show that under the dynamic DC interference of soil environment, the anodic polarization behavior of magnesium alloy was activated and controlled. When the interference was applied for 3 days, the actual corrosion rate reached 18.0 mm/a. As the interference time prolonged, the magnesium alloy anode continued to corrode and dissolve, resulting in a positive potential shift and an exponential increase in grounding resistance. With dynamic DC interference, the effective grounding area of magnesium alloy anode corrosion decreased. The formation of Mg (OH) ₂ and MgCO₃ oxide layers on the surface, as well as soil water and electricity migration causing dryness around the ground bed, led to an increase in the grounding resistance of the anode ground bed, a decrease in drainage efficiency, or the failure of the ground bed.