Surface roughness and the corrosion resistance of 21Cr ferritic stainless steel

The influence of surface topography on corrosion resistance of 21Cr ferritic stainless steel was studied. The surface topography was modified by changing the grinding conditions such as load, speed, and fluid type and its correlation with corrosion resistance was examined. Results showed that the corrosion behavior was correlated well with the reduced valley depth of the surface, while other roughness parameters including roughness average, root mean square roughness average, skewness, and others showed poor correlations with corrosion behavior. Another salient observation was the strong influence of the type of the grinding-fluid on the topography of the ground surface.

► Surface roughness was strongly affected by the wettability of the grinding fluid.
► The friction level was higher with the hydrophobic grinding fluid, due to poor lubrication.
► The reduced valley depth showed a good correlation with corrosion resistance when Ra was greater than 0.5 μm.