690 MPa级耐候桥梁钢在模拟工业大气环境下的腐蚀行为研究

Corrosion Behavior of 690 MPa Weathering Bridge Steel in Simulated Industrial Atmosphere

采用周期浸润加速腐蚀实验和电化学方法,结合场发射扫描电镜 (FE-SEM)、X射线衍射 (XRD)、电子探针 (EPMA) 等表面测试技术研究了 690 MPa 高性能耐候桥梁钢在模拟工业大气环境中的腐蚀行为。结果表明,在腐蚀初期,以贝氏体为主的Q690qENH钢的耐蚀性优于含有铁素体和珠光体组织的Q235钢;在腐蚀后期,Q690qENH钢腐蚀速率逐渐减小且远低于Q235钢,Q690qENH钢锈层中Cu、Cr、Ni合金元素的富集提高了锈层的致密性和稳定性,对腐蚀性介质的抵抗作用更强,锈层保护性参数 α/γ*更大。电化学结果也表明,Q690qENH 钢的锈层电阻及线性极化电阻更大,保护作用更强,因此在模拟工业大气环境中耐蚀性明显优于Q235 钢。

The corrosion behavior of 690 MPa high performance weathering bridge steel in a laboratory simulated industrial atmosphere was investigated by means of cyclically alternative immersion-drying accelerated corrosion test, electrochemical test, scanning electron microscopy (SEM), X-ray diffractometer (XRD), electron probe (EPMA) and other surface testing techniques. The results show that the corrosion resistance of Q690qENH steel composed mainly of bainite is better than that of Q235 steel composed of ferrite and pearlite at the early stage of corrosion. At the later stage of corrosion, the corrosion rate of Q690qENH steel decreases gradually and which is much lower than that of Q235 steel. The enrichment of alloying elements Cu, Cr and Ni in the rust layer of Q690qENH steel improves the denseness and stability of the rust layer, which has stronger resistance to corrosive medium, and higher α/γ* ratio of the so-called rust layer protectiveness. The electrochemical test results also show that the rust resistance and linear polarization resistance of Q690qENH steel are larger and the protective effect is stronger.Therefore, the corrosion resistance of Q690qENH steel is obviously better than that of Q235 steel in simulated industrial atmospheric environment.