Corrosion Behavior of Q235 and Q345 Carbon Steel in Hongyanhe Atmosphere

The corrosion behavior of Q234 and Q345 steel in Hongyanhe atmosphere was investigated by atmospheric exposure corrosion test, corrosion mass loss test, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion rate of Q345 steel was higher than that of Q235 steel at the early stage. With the increase of exposed time the corrosion rate became no difference. When exposed for 18 months, the decline of corrosive rate turned into plateau progression. The atmospheric corrosion level of Hongyanhe is C3. In this atmosphere the synergy of SO₂ and Cl^- initiated the formation of sulfate in the low carbon steel rust layer and the formation of cracks throughout the whole rust layer slowed down the corrosion rate of low carbon steel.