The Ultrasonically Induced Cavitation Corrosion of UNS N08825 in Seawater

Abstract A cavitation facility was used to study the cavitation corrosion behavior of alloy UNS N08825 (Incolloy 825) in seawater. The work included measurements of mass loss in the presence and absence of cavitation and free corrosion potentials. The cavitation tests were made at a frequency of 20 KHz and at a temperature of 25°C. Cavitation conditions caused an electrochemically active shift in the free corrosion potential for UNS N08825. 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 nonconductive medium in order to distinguish between the mechanical and electrochemical factors that contribute to metal loss. Results indicated that the mechanical factor has an overriding role of 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 factors were determined to be the leading cause of metal loss.