Synergistic effect of cavitation erosion and corrosion of various engineering alloys in 3.5% NaCl solution

The cavitation erosion and corrosion characteristics of various engineering alloys including grey cast iron, steels, copper-based alloys and stainless steels were studied by means of a 20 kHz ultrasonic vibrator at a peak-to-peak amplitude of 30 mu m in distilled water and in 3.5% NaCl solution at 23 degrees C. The contributions of pure mechanical erosion, electrochemical corrosion, and the synergism between erosion and corrosion to the overall cavitation erosion-corrosion in 3.5% NaCl solution were determined. It was found that in 3.5% NaCl solution, the effect of corrosion on the overall cavitation erosion-corrosion was most pronounced in mild steel and grey cast iron, and negligible in stainless steels. The stainless steels only suffered pure mechanical erosion in 3.5% NaCl solution in the presence of cavitation owing to the unfavourable local environment for pit growth. (C) 2000 Elsevier Science S.A. All rights reserved.