Atmospheric Corrosion Resistance of Weathering Angle Steels in a Simulated Industrial Atmosphere

The influences of RE, Cr, P and P-RE elements on atmospheric corrosion resistance behaviors of weathering angle steels in a simulated industrial atmosphere were investigated by periodic immersion wet/dry cyclic corrosion test. According to weight loss test and rust analysis results, the corrosion rate is relatively faster in the initial stage of the corrosion since the compositions of rust layer are mainly gamma-FeOOH and Fe3O4. Then, gamma-FeOOH and Fe3O4 gradually transform to alpha-FeOOH and the corrosion rate reduces. The increasing amount of alpha-FeOOH with enhanced corrosion resistance is related to the addition of phosphorus element and the enrichment of copper, chromium and nickel elements in inner rust layer. Besides, rare earth can reduce the content of chromium and work with phosphorus to improve atmospheric corrosion resistance of steel. Consequently, weathering angle steel containing phosphorus and rare earth elements exhibits high corrosion resistance, and the electrochemical measurement on it indicates that the anodic process is inhibited and the evolution of resistance increases with the prolongation of immersion time.