Investigation of the Corrosion Behavior of L245 Steel in 3.5 wt.% NaCl Solution with Varying Concentrations of Na2S2O3

In the extraction of shale gas, Cl^- and S₂O₃^2- are one of the important factors causing severe corrosion and failure of equipment and pipelines. Addressing the Cl^-/S₂O₃^2- corrosion challenge in shale gas exploitation pipeline steels, this study evaluates the corrosion rates of L245 steels under diverse conditions, including S₂O₃^2- concentration and exposure time, utilizing the weight loss method. The microstructural, elemental, and phase compositions of the corrosion products were examined, and the electrochemical behavior of L245 steel was scrutinized under various conditions. Findings indicate that S₂O₃^2- addition intensifies localized corrosion on L245 steel, with the corrosion nature being contingent upon S₂O₃^2- concentration in the Cl^--containing solution. Concurrently, an escalation in S₂O₃^2- concentration correlates with a reduction in capacitive arc diameter and a significant decrease in film resistance, culminating in an accelerated corrosion rate.