The cavitation erosion of ductile cast iron with ferrite-pearlite microstructure was analyzed based on ultrasonic experiments performed according to ASTM G32-2010 and the resistance was compared to the C45 steel with similar hardness. The microstructural observation of the surface for different exposure times to the ultrasonic cavitation reveals the fact that the process initiates at the nodular graphite-ferrite interface and is controlled by micro-galvanic activities and mechanical factors. The cavitation erosion resistance was evaluated based on the evolution of the mean depth erosion and the mean depth erosion rate as a function of the cavitation time. The cavitation erosion rate of the cast iron is up to 1.32 times higher than the one of the C 45 steel with similar hardness. This is explained by the occurrence of stress concentrators due to the expulsion of the graphite from the metallic matrix.

Ultrasonic cavitation erosion experiments were performed on Ti-6Al-4V alloys samples in annealed, nitrided and nitrided and subsequently heat treated state. The protective oxide layer formed as a result of annealing and heat treatment after nitriding is eliminated after less than 30 min cavitation time, while the nitride layer lasts up to 90 min cavitation time. Once the protective layer is removed, the cavitation process develops by grain boundary erosion, leading to the expulsion of grains from the surface. The gas nitrided Ti-6Al-4V alloy, forming a TixN surface layer, proved to be a better solution to improve the cavitation erosion resistance, compared to the annealed and nitrided and heat treated state, respectively. The analysis of the mean depth of erosion rate at 165 min cavitation time showed an improvement of the cavitation erosion resistance of the nitrided samples of up to 77% higher compared to the one of the annealed samples.

The aluminum alloy type 5083, which has high corrosion resistance, excellent weldability, and good strength, is widely used in shipbuilding, automotive, aerospace, and industrial construction. The present paper has the aim of establishing a possible correlation between mechanical properties, structural characteristics, and cavitation erosion properties of the 5083 alloy after applying different heat treatments. Different homogenization heat treatments (350 °C, 450 °C) were applied, each followed by cooling in air and artificial aging at different temperature (140 °C and 180 °C) with three maintenance periods, 1 h, 12 h, and 24 h. The experiments concerning cavitation resistance of the experimental samples were completed in accordance with ASTM G32-2016. The cavitation erosion resistance were determined either by analytical diagrams MDER (or MDE) vs. cavity attack duration, or by measuring the maximum erosion attack by stereomicroscopy and scanning electron microscopy. Finally, the best combination of heat treatments applied to cast aluminum products type 5083 is homogenization at 350 °C followed by artificial aging at 180 °C, at which the highest mechanical characteristics are obtained, a resilience of 25 J/cm², a grain size of 140–180 μm, and a maximum depth of the erosion MDEmax around 14–17 µm.

Paper present a new relation describing the curve MDER(t) which mediates the experimentally obtained values of the mean depth erosion rates. These curves are used to characterize the cavitation erosion behavioor of materials tested in the Cavitation Laboratory of Timisoara Polytechnic University. Practically the new relation is an improvement of the analytical model established in 2004 by Bordeasu and coworkers, by introducing a supplementary element, which take into consideration the shape of the zone in where the cavitation erosion rate became stable and has linear variation. These addition allow increasing the approximation of the experimental values and also putting into evidence the tiny differences between different materials (various types of stainless steels, highly alloyed bronzes etc.) which till now were considered with similar resistance. Thus, the supplementary term allow a better differentiation resulting from the chemical composition, the structure and the mechanical properties.