Analysis of metal electrochemical corrosion behavior and velocity under AC stray current

Abstract

Stray currents can cause electrochemical corrosion of metals, accelerate material aging, and even pose safety hazards. By studying corrosion behavior and speed, the degree of damage caused by stray currents to metals can be evaluated, protective measures (cathodic protection, insulation design, etc.) can be optimized, the service life of metal structures can be extended, maintenance costs can be reduced, and the safe and stable operation of power systems and infrastructure can be ensured. Therefore, research on the electrochemical corrosion behavior and velocity analysis method of metals under AC stray current. This article mainly explores the influence of different alternating current (AC) stray current densities on the electrochemical corrosion behavior of 316L stainless steel. The experiment used Yingtan soil simulation solution, and analyzed the changes in indicators through electrochemical testing, corrosion morphology observation, and corrosion rate calculation. The results indicate that the corrosion rate of 316L stainless steel in soil simulation solution shows a trend of first decreasing and then increasing when disturbed by AC stray current density. In the initial stage, the synergistic effect of high concentrations of Cl^– and O₂ leads to a faster corrosion rate. Over time, corrosion products increase and form a film layer, which hinders harmful ion erosion and slows down the corrosion rate. However, after prolonged immersion, the corrosion product film may crack, crevice, or even peel off, causing crevice corrosion and galvanic corrosion, accelerating the corrosion process. AC stray current forms a "tip discharge" through the defect, further exacerbating corrosion. With the increase of AC interference current density, the corrosion rate of 316L stainless steel significantly increases, and the main corrosion form changes from uniform corrosion to localized corrosion. When the stray current density is greater than or equal to 200 A/m², the corrosion degree of 316L stainless steel under the peeling coating reaches severe corrosion. This study is of great significance for understanding the impact of AC stray currents on metal corrosion and developing effective protective measures.