The generation of surface roughness during slurry erosion-corrosion and its effect on the pitting potential

Results of experiments performed to isolate the effect of surface roughness generated during slurry erosion-corrosion of 304L stainless steel are presented. Surfaces prepared by grinding to different finishes show that increasing the roughness lowers the pitting potential in chloride solution. Subsequent erosion by an aqueous sand slurry then alters this pitting potential (E(p)), as measured in the solution phase alone, in a manner dependent on the initial surface roughness. Surfaces which were initially rougher show a pronounced rise in E(p) after erosion, while those with an initially smoother finish show a fall in E(p) after erosion. Measurement of E(p) during erosion-corrosion does not fit either process, with values of E(p) lower than those predicted from the surface roughness alone. Copyright (C) 1996 Elsevier Science Ltd