Cavitation Damage on Surface of Pure Copper by Cavitating Water Jet Erosion

Cavitating water jet erosion was carried out on pure copper for different times by a self-made cavitating water jet device. The microstructure, damage morphology, surface roughness and cross section hardness of the specimens after erosion were studied and the cavitation damage process and mechanism were also analyzed. The results show that the bending deformation of grains occurred in the direct water jet zone while the cross section microstructure in the mixed water jet zone remained unchanged. After water jet erosion for 5 min, some cavitation pits and needle-like cavitation pits appeared in the direct water jet zone. With the increase of erosion time, the amounts of cavitation pits and needle-like cavitation pits increased and the grain morphology appeared gradually. Meanwhile a large amount of deformation slip bands and metal spalling phenomena were also observed. In the mixed water jet zone, cavitation pits were large and shallow and grain morphology emerged entirely with time increasing. The needle-like cavitation pits around gathered and led to a small number of metal spalling, which was the reason why the cavitation pit became larger and larger. With the increase of erosion time, the surface roughness of the two zones increased gradually, and the surface roughness of the mixed water jet zone was larger than that of the direct water jet zone, so were the hardening layer thickness and near surface hardness.