高强耐候钢在NaCl溶液中的腐蚀锈层特征和耐腐蚀性研究

为了研究高强耐候钢Q450NQR1和B2在2.0%NaCl溶液中的腐蚀锈层特征，获得其耐腐蚀性规律。采用交流阻抗谱（Electrochemical impedance spectroscopy，EIS）、X射线衍射仪（X-ray diffracmeter，XRD）、扫描电镜（Scanning electron microscope，SEM）和电感耦合等离子体（Inductively coupled plasma，ICP）手段分析它们的腐蚀行为和锈层特征，并讨论合金元素Cu、Ni、Cr、Mo等对耐腐蚀性的影响。结果表明：B2耐候钢的耐蚀性要优于Q450NQR1耐候钢的，其锈层表现出较高的电荷转移电阻（R_t）特征；两种耐候钢的非连续性（Non-adherent rusts，NAR）和连续性（Adherent rusts，AR）型锈层物相组成分别一致，但含量有差别；NAR型锈层主要由大量的γ-FeOOH和少量的Fe₃O₄、α-FeOOH组成，紧贴基体的AR型锈层几乎全为Fe₃O₄。Cu、Ni、Cr、Mo合金元素在两种锈层中的分布不同，影响着NAR型锈和AR型锈的协同保护作用，从而改变了基体表面的锈层特征，稳定锈层的存在可显著抑制Cl^-渗入，有助于改善材料耐腐蚀性。

A Study on the Rust Characteristics and Corrosion Resistance of High Strength Weathering Steels in NaCl Solution

In order to clarify the rust characteristics and the corrosion resistance rules, two kinds of weathering steels, Q450NQR1 and B2, have been investigated using 2.0% NaCl solution. The EIS, XRD, SEM and ICP are used for analysis. The effects of alloying elements, such as Cu, Ni, Cr, Mo on the corrosion resistance are also discussed. The results indicate that B2 shows greater corrosion resistance than that of Q450NQR1. And its rust layer behaves a higher charge transfer resistance (R_t). Besides, the two steels have similar constituents in both non-adherent rust (NAR) layers and in adherent rust (AR) layers, but different contents. The NAR layers for both steels consist of large portion of γ-FeOOH and few Fe₃O₄ and α-FeOOH; the AR layers, which are close to the base, consist almost entirely Fe₃O₄. The results of ICP show that Cu, Ni, Cr, Mo are distributed differently in NAR and AR layers and affect the cooperative protection between the two layers; thus, these phenomena stabilize the rust layers and change their characteristics on the base. These stable rust layers can significantly prohibit the penetration of Cl^-, which can improve the corrosion resistance.