Influence of surface roughness on the electrochemical behavior of carbon steel

The effect of the surface roughness of carbon steel on corrosion properties was investigated using electrochemical tests, and surface and Kelvin probe force microscopy (KPFM) analyses. The results of electrochemical tests show that the corrosion rate of carbon steel is increased as the surface roughness increases. It was estimated using KPFM measurement that the difference in the Volta potential between the peak and the valley increased with increasing surface roughness. As the peak has a lower potential than that of the valley, the peak acts as an anode. The surface roughness affects the Volta potential, and the Volta potential difference is inversely proportional to electron work function (EWF). The larger difference in Volta potential between the peak and valley on the rougher surface and the smaller EWF accelerated the micro-galvanic corrosion between them. The surface analyses reveal that corrosion initiated along the peak lines. The results from this study suggest that an increase of surface roughness leads to a decrease of the corrosion resistance.