Reactive molecular dynamics study on carbon steel corrosion induced by chloride: Effects of applied potential and temperature

Abstract

The corrosion and oxidation mechanisms of steel in chloride-contaminated environment were studied through the utilization of reactive molecular dynamics simulations with self-developed force fields under various applied electric fields and temperatures. The impact of variations in the external electric field on the thickness of the oxide layer and the dissolution of iron during the corrosion reaction process was scrutinized. The results reveal that under an electric field strength of 10 MV/cm, marginal corrosion was observed within the iron matrix during the simulation period. The surface lattice of the iron matrix retained a relatively intact and regular arrangement. However, under alternative external electric field conditions, as the strength of the external electric field increased, the corrosion behavior of iron in chloride ion solutions became increasingly severe, leading to deeper oxidation levels. Additionally, localized pitting on the iron matrix surface gradually evolved into larger corroded spots. Simulation results within the temperature range studied (278 K, 298 K, 318 K) suggest that temperature elevation amplifies the thermodynamic energy of chemical reactions on the iron surface, consequently leading to a reduction in the bond strength of Fe-O and increase in the corrosion extent.