在青岛海湾大桥现场大气中对ZG20Mn钢进行了7 a的暴露试验, 通过扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等研究了其腐蚀行为。结果表明: 在青岛海湾大桥现场大气中, 随着暴露时间的延长, ZG20Mn钢的腐蚀速率呈现下降的趋势, 平均腐蚀深度与暴露时间符合幂函数关系; 随着暴露时间的延长, ZG20Mn钢局部腐蚀的趋势增强, 点蚀深度增大; MnS夹杂物和含氯盐颗粒会促进腐蚀的产生; 在青岛海湾大桥现场大气中暴露7 a后, ZG20Mn钢的腐蚀产物主要为α-FeOOH、α-Fe₂O₃和Fe₃O₄, α-FeOOH的不断生成和沉积是造成钢大气腐蚀速率逐渐降低的主要原因, 而Fe₃O₄的存在表明具有电化学活性的腐蚀产物参与了阴极去极化过程。

Exposure test was carried out on ZG20Mn steel in the atmosphere of Qingdao Bay Bridge for 7 a. The corrosion behavior of ZG20Mn steel was studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that in the atmosphere of Qingdao Bay Bridge, with the increase of exposure time, the corrosion rate showed a downward trend. The relationship between average corrosion depth and exposure time conformed to a power function. With the increase of exposure time, the tendency of localized corrosion of ZG20Mn steel increased, and the depth of pitting corrosion increased. MnS inclusions and chlorinated salt particles promoted the occurrence of corrosion. The corrosion products of ZG20Mn steel exposed to the atmosphere of Qingdao Bay Bridge for 7 a were mainly composed of α-FeOOH, α-Fe₂O₃ and Fe₃O₄. The continuous generation and deposition of α-FeOOH was the main reason for the gradual decrease of corrosion rate of steel in atmosphere. The presence of Fe₃O₄ indicated that the corrosion products with electro-chemical activity participated in the cathodic depolarization process.