Corrosion Behavior of Q235 Carbon Steel in Red Soil

Morphology and corrosion product of Q235 carbon steel used for many years in substation grounding grid in red soil were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that corrosion products on the grounding grid surface were mainly composed of iron oxides including Fe2O3, Fe3O4, FeOOH. And the existence of Cl- could accelerate the corrosion of Q235 carbon steel. The largest corrosion rate of Q235 carbon steel was achieved when the water content was wt20%, and the corrosion current density of Q235 carbon steel had same tendency with the increase of content of Cl- and SO42-, showing increase first and then decrease, and it can be divided into three intervals. The corrosion rate of Q235 carbon steel in red soil presented the tendency of first decrease and then increase in small range with the increase of experimental time. The corrosion mechanism of Q235 carbon steel in red soil did not change in the accelerated corrosion experiment which had a good correlation with the corrosion in worksite.