碳素结构钢在川藏地区的大气腐蚀行为研究

Study on Atmosphere Corrosion Behavior of Carbon Structural Steel in S in Sichuan and Xizang

摘要: 为研究碳素结构钢在川藏地区复杂环境下大气腐蚀行为，选择耐候指数不同的三种碳素结构钢放置于泸定、攀枝花和拉萨三地的河流周边开展自然腐蚀试验。经过一年的自然暴露后，样品依据国标除锈后测定首年腐蚀质量损失并预测长期腐蚀质量损失，采用SEM、EDS、XRD、Tafel极化、EIS对样品进行分析表征。结果表明泸定与拉萨样品首年腐蚀速率损失接近，介于2.12 μm·a⁻¹至4.34 μm·a⁻¹，攀枝花存在工业大气污染，导致锈层较厚且深度不均，能谱分析得到较高浓度的S元素沉积，低耐蚀性的DH36首年腐蚀速率达20.11 μm·a⁻¹。腐蚀产物以Fe₂O₃、Fe₃O₄、α-FeOOH、γ-FeOOH为主，Fe₃O₄含量大于Fe₂O₃，α-FeOOH含量显著低于文献报道的模拟试验结果。电化学分析表明锈层增厚有助于提高耐蚀性，表现为腐蚀电位升高，腐蚀交换电流密度降低以及阻抗增大，耐候指数较高的两种钢材耐蚀性改善大于低耐候指数的钢材，归因于锈层稳定性和致密性良好。

Abstract: To investigate the atmospheric corrosion behavior of carbon structural steels in the complex environments of the Sichuan-Xizang region, three types of carbon structural steels with different weathering indices were selected and subjected to natural corrosion tests near rivers in Luding, Panzhihua, and Lhasa. After one year of natural exposure, the samples were derusted in accordance with national standards to determine the first-year corrosion mass loss and to predict the long-term corrosion mass loss. The samples were characterized by SEM, EDS, XRD, Tafel polarization, and EIS. The results show that the first-year corrosion rates of the samples from Luding and Lhasa were similar, ranging from 2.12 to 4.34 μm·a⁻¹. In Panzhihua, the presence of industrial atmospheric pollution led to thicker and more unevenly distributed rust layers, with EDS revealing relatively high sulfur deposition. The low-corrosion-resistance steel DH36 exhibited a first-year corrosion rate as high as 20.11 μm·a⁻¹. The corrosion products were mainly composed of Fe₂O₃, Fe₃O₄, α-FeOOH, and γ-FeOOH, with the Fe₃O₄ content being higher than that of Fe₂O₃, and the α-FeOOH content being significantly lower than that reported in simulated test results in the literature. Electrochemical analysis indicated that the thickening of the rust layer contributed to improved corrosion resistance, as manifested by increased corrosion potential, decreased corrosion exchange current density, and increased impedance. The two steels with higher weathering indices showed greater improvement in corrosion resistance than the steel with a lower weathering index, which is attributed to the better stability and compactness of their rust layers.