Corrosion Resistance of Q690qENH Steel Exposed to Atmosphere for Two Years

Atmospheric exposure experiment was carried out in Anshan and Bayuquan areas for 2 years to analyze the corrosion resistance of Q690qENH high strength bridge weathering steel and Q345qE bridge steel made by Ansteel. The mass loss measurement,electrochemicaltesting,rust layer sectional morphology and XRD were used to study the corrosion behavior of the samples after exposure. The results showed that the 2-year corrosion rates of Q690qENH steel were 0.0146mm/a and 0.0182mm/a in Anshan and Bayuquan respectively and the 2-year corrosion rates of Q345 steel were 0.018 1 mm/a and 0.026 3 mm/a respectively. The corrosion resistance of Q690qENH steel was better than that of Q345qE steel. The self-protective efficiency of Q690qENH steel was high in marine atmospheric environment. The anodic process of Q690qENH steel was more significantly blocked and its anodic current was less than that of Q345qE. The part enrichment of Cu,Ni,Cr elements in Q690qENH steel promoted the formation of the protective rust layer. The corrosion resistance of Q690qENH steel was better than that of Q345qE steel mainly due to the protective inner rust layer.