Chloride ion (Cl^-) attack is a main reason for localized corrosion of reinforcing steel in concrete. Study on the effect of Cl^- on corrosion behavior of the steel is of importance for corrosion protection. In this study, reinforcing steel (Q235 carbon steel) passivity in simulated polluted concrete pore solutions at pH 11.50 with different Cl^- concentrations was studied by a scanning micro-reference electrode technique, combined with polarization curve and electrochemical impedance spectroscopy measurements and an electron probe method. The results indicated that the steel remained passive in the solution without Cl^-. The steel passivity might be destroyed by the Cl^- attack, and the pitting corrosion took place. The chloride threshold level for localized corrosion of the steel in the solution was 0.010 to 0.020 M Cl^-. Pitting corrosion occurred preferentially at MnS inclusion locations, and the Cl^- was adsorbed at these locations resulting in depassivation of the steel surface.

氯离子（Cl ^-）侵蚀是混凝土中钢筋局部腐蚀的主要原因。研究Cl ^-对钢腐蚀行为的影响对于腐蚀防护具有重要意义。在这项研究中，通过扫描微参比电极技术，结合极化曲线和电化学阻抗谱测量以及电子探针，研究了钢筋（Q235 碳钢）在 pH 11.50 和不同 Cl ^-浓度的模拟污染混凝土孔隙溶液中的钝化性。方法。结果表明，钢在不含Cl ^-的溶液中保持钝化。钢的钝化可能被 Cl ^-攻击，并发生点蚀。溶液中钢局部腐蚀的氯化物阈值为 0.010 至 0.020 M Cl ^-。点蚀优先发生在 MnS 夹杂物位置，Cl ^-吸附在这些位置导致钢表面去钝化。