Observation of microstructural deformation behavior in metals caused by cavitation impact

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.