通过周期浸润加速腐蚀试验、腐蚀失重试验、扫描电镜(SEM)、X射线衍射(XRD)、电化学测试等方法, 研究了湿热工业-海洋大气环境中, 铝对桥梁钢耐蚀性的影响。结果表明: 试验钢的腐蚀过程遵循幂函数分布规律, 锈层以向内生长为主; 铝具有强化铁素体组织、抑制腐蚀产物结晶和促进具有保护作用的细晶氧化物膜生成等优势, 有利于提高试验钢的耐蚀性, 但铝氧化物容易与含硫酸发生反应, 使锈层中形成较多的锈巢和裂纹; 随腐蚀时间的延长, 裂纹增多, 锈巢增大, 锈层结构不断被破坏, 到腐蚀后期, 生成垂直裂纹, 加速了腐蚀性粒子的入侵, 最终导致腐蚀速率上升, 钢基体腐蚀恶化。

The effect of Al on the corrosion resistance of bridge steel in simulated industrial-marine atmosphere was investigated by wet/dry alternate immersion corrosion testing, mass loss testing, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical testing. The results indicate that the corrosion process of the experimental steel shows a good agreement with the power function, and the growth trend of the rust layer is mainly inward. Al has the advantages in strengthening ferrite microstructure, inhibiting the crystallization of corrosion products, and promoting the formation of a dense protective film made of fine-grained oxide, which can help to improve the weather resistance of the steel. However, in the humid and warm industry-marine atmosphere, acids could be generated by the reaction between SO2 and H2O, leading to the corrosion of the rust layer and steel substrate. Besides, compared with iron oxides, the Al-containing oxides are easier to react with acids and result in more rust nests and cracks forming in the rust layer. With the increase of corrosion time, the number of cracks increases, and the volume of rust nests becomes bigger, the structure of the rust layer is thus continuously being damaged. By the late stage of corrosion, the infiltration of corrosive particles is accelerated by the formation of the cracks perpendicular to the steel substrate, leading to the increase of corrosion rate and the decline of corrosion resistance of the steel.