Observation of Microstructural Deformation Behavior in Metals Caused by Cavitation Impact

Abstract

To clarify the erosion mechanism of cavitation, we pay attention to the internal changes in grains caused by cavitation impact. The vibratory cavitation test based on ASTM G32 was carried out and the cross section of directly under the eroded surface of a specimen was observed using the electron backscattering diffraction (EBSD) technique. The situations of grain boundaries and the changes in the crystal orientations of grains in aluminum, copper, and steel were analyzed. As a result, the following observations were made. Cavitation impact causes grain refining of sub-micrometer order near the eroded surface. There exist small changes in crystal orientation in grains. In steel, grain boundaries were generated on the eroded surface and were growing inward in the grain. Finally, the mechanism of internal deformation of grains caused by cavitation impact was discussed.

Material Removal and Surface Modification of Copper under Ultrasonic-Assisted Electrochemical Polishing

“…Ultrasonic cavitation, as a nonlinear acoustic phenomenon, involves the dynamic processes of expansion, oscillation, compression, and collapse in a liquid medium [6][7][8]. Studies have reported that ultrasonic vibration helps to eliminate bubbles in the electroplating solution and prevents interference from hydrogen bubbles during the coating formation process, thereby increasing the density and crystallinity of the coating, reducing the formation of pores, and promoting denser coating formation, resulting in submicron-level grain refinement on the eroded surface [9,10]. Liu et al [11] found that ultrasonic cavitation is suitable for processing the surface microstructure of workpieces to improve processing for enhanced bonding strength.…”