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<p>This study investigates the synergistic corrosion behavior of DH36 steel under the combined influence of chloride (Cl⁻) and hydrogen (H⁺) ions, simulating marine splash zone conditions. Electrochemical techniques—including polarization curves and electrochemical impedance spectroscopy (EIS)—combined with microstructural characterization (SEM, EDS, and XRD) were used to evaluate corrosion mechanisms in NaCl solutions (1–7.5 wt%) and in acidic environments containing 3.5 wt% NaCl with HCl concentrations ranging from 0 to 0.6&#xa0;mol/L. The results indicate that increasing Cl⁻ concentration lowers the corrosion potential (from − 519 mV to -588 mV) and raises the corrosion current density, suggesting an acceleration of the corrosion rate. Notably, at NaCl concentrations above 5 wt%, the pit density increases to approximately 11,437 pits/mm² (at 7.5 wt%), while the pit size expands by about 80%. Under acidic and chloride-rich conditions (HCl ≥ 0.4&#xa0;mol/L), corrosion intensifies further: corrosion products become porous, promoting the formation of longitudinal grooves and deep pits. EIS data confirm a decrease in polarization resistance (e.g., R<sub>p</sub> decreases from 4,211 Ω·cm² to 2,297 Ω·cm² in 7.5 wt% NaCl), and the appearance of Warburg impedance indicates diffusion-controlled corrosion processes. The dominant mechanism involves electrochemical reactions in which Cl⁻ and H⁺ act synergistically to enhance Fe dissolution through soluble intermediates such as adsorbed [FeCl(OH)]⁻, while acidic conditions suppress passivation. These findings highlight the significant vulnerability of DH36 steel in aggressive marine environments and offer important insights for improving corrosion resistance in offshore structures.</p>

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Corrosion behavior and mechanism of DH36 steel under synergistic chloride and hydrogen ion influence

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月31日

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  • Jiantao Wang,
  • Bochen Jiang

摘要

This study investigates the synergistic corrosion behavior of DH36 steel under the combined influence of chloride (Cl⁻) and hydrogen (H⁺) ions, simulating marine splash zone conditions. Electrochemical techniques—including polarization curves and electrochemical impedance spectroscopy (EIS)—combined with microstructural characterization (SEM, EDS, and XRD) were used to evaluate corrosion mechanisms in NaCl solutions (1–7.5 wt%) and in acidic environments containing 3.5 wt% NaCl with HCl concentrations ranging from 0 to 0.6 mol/L. The results indicate that increasing Cl⁻ concentration lowers the corrosion potential (from − 519 mV to -588 mV) and raises the corrosion current density, suggesting an acceleration of the corrosion rate. Notably, at NaCl concentrations above 5 wt%, the pit density increases to approximately 11,437 pits/mm² (at 7.5 wt%), while the pit size expands by about 80%. Under acidic and chloride-rich conditions (HCl ≥ 0.4 mol/L), corrosion intensifies further: corrosion products become porous, promoting the formation of longitudinal grooves and deep pits. EIS data confirm a decrease in polarization resistance (e.g., Rp decreases from 4,211 Ω·cm² to 2,297 Ω·cm² in 7.5 wt% NaCl), and the appearance of Warburg impedance indicates diffusion-controlled corrosion processes. The dominant mechanism involves electrochemical reactions in which Cl⁻ and H⁺ act synergistically to enhance Fe dissolution through soluble intermediates such as adsorbed [FeCl(OH)]⁻, while acidic conditions suppress passivation. These findings highlight the significant vulnerability of DH36 steel in aggressive marine environments and offer important insights for improving corrosion resistance in offshore structures.