The Cavitation Erosion Behaviour of UNS N04400 Alloy in Seawater

Abstract UNS N04400 alloy was exposed to cavitation conditions using a vibratory cavitation testing apparatus in seawater. The work also included measurements of free corrosion potentials, and mass loss in the presence and absence of cavitation. The cavitation tests were made at a frequency of 20 KHz and at temperatures of 25°C. Cavitation conditions caused a noble shift in the free corrosion potential for this alloy. Cavitation also increased the rate of mass loss of this alloy by several orders of magnitude with respect to stagnant conditions. Another set of cavitation experiments was also carried out for this alloy in a distilled water in order to distinguish between the mechanical and electrochemical factors that contribute to metal loss. Results indicated that the mechanical factor has an over-riding role in metal loss of this alloy. Cavitation made the surface of this alloy very rough, exhibiting large cavity pits in the middle region of the attacked area as revealed by the scanning electron microscope (SEM). Mechanical, electrochemical and metallurgical factors were determined to be the leading cause of metal loss.