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

Abstract

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 μm in distilled water and in 3.5% NaCl solution at 23°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.