Pitting corrosion induced on high-strength high carbon steel wire in high alkaline deaerated chloride electrolyte

Abstract

Abstract Electrochemical response causing pitting corrosion of high-strength high carbon steel wire in deaerated electrolyte at pH 13.4 due to different chloride ion (Cl−) concentrations was investigated using open circuit potential, cyclic potentiodynamic polarization, and anodic potentiostatic application (APA) within the passive zone. Results showed that the higher the Cl− concentration, the more negative the corrosion potential becomes. In the high alkaline pH 13.4 without the presence of free oxygen gas the Cl− concentration could reach up to 1 M not showing pitting potential. An inverse relationship between anodic potentials (APs) and Cl− concentrations was found and the rate of corrosion within passive period was almost a constant, not influenced by the Cl− concentrations. Faraday´s law failed to predict the mass loss when active pitting corrosion occurred. Green rust and hydrogen gas were observed during active pitting corrosion under APA. Pitting corrosion mechanism in the deaerated high alkaline electrolyte was then proposed. This work deduces that in the deaerated electrolyte at pH 13.4 with the presence of Cl−, it is essential to apply the APs within the safety margin on the high-strength high carbon steel wire to avoid active pitting corrosion and hydrogen embrittlement.