Hardening Peculiarities of Metallic Materials During Wear Under Ultrasonic Cavitation

Abstract

An attempt was made to determine the mechanism of energy transfer (by microjets or shock waves) from the cavitation zone to the metal surface, which is based on the analysis of metal hardening during cavitation wear. The research was carried out using technical copper and silumine AK12pch. Two batches of cylindrical samples were made from each material. Frontal surfaces of the samples from the first batch were ground, polished, and subjected to cavitation exposure. It was carried out on an ultrasonic magnetostrictive vibrator in fresh water at a frequency and amplitude of oscillations of the concentrator face equal to 22 kHz and 28 μm, respectively. During the incubation wear period, the microhardness of copper and silumin was measured and the maximum achievable microhardness, corresponding to the end of the hardening period, was determined. Samples of the second batch were plastically deformed under uniaxial compression to various degrees of deformation. Then, the deformed samples were cut into two halves along their axis, the plane of the obtained section was ground and polished, and after that the microhardness was measured in the center of the section. According to the measurement results, the correlation between the microhardness and the intensity of plastic deformation was determined for each material. Using the dependence of microhardness on the deformation intensity, an assessment was made for the strain, which corresponds to the onset of fracture of a metal surface under cavitation. It turned out that the plastic deformation value obtained in this way corresponds to the stress state of the surface layers.