When steels are eroded in corrosive slurry, the material loss rate due to erosion will increase with anodic current density. This phenomenon is regarded as corrosion-enhanced erosion. A recent study in our laboratory indicates that the corrosion-enhanced erosion of carbon steels results from corrosion-induced hardness degradation in surface layer. In this work, the interaction between mechanical and electrochemical factors during the erosion corrosion of carbon steel in slurries is experimentally investigated to correlate the mechanism of corrosion-enhanced erosion to the corrosion-induced degradation of surface mechanical property. The effect of anodic dissolution on the surface mechanical property was evaluated by a nanoindentation technique. The results show clearly that the anodic current reduces the hardness in the surface layer and the amplitude of surface hardness degradation depends heavily on the solution pH. Corrosion in acidic solutions leads to a larger hardness drop than that in neutral or alkaline solution. It is well recognized that the erosion resistance of carbon steels is reduced with decreasing hardness. Based on the chemo-mechanical model developed by our group, the corrosioninduced hardness degradation is an important mechanism of the corrosion-enhanced erosion. The large hardness loss in corrosive slurries leads to a significant degradation in erosion resistance and higher erosion wastage.
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