Considerations on the Behaviour and Resistance of Aluminium Alloys to Cavitation Erosion

Aluminum alloys are known for their wide application in the automotive, river and marine boat constructions, but also in hydraulic systems (radiators/oil coolers). Their use is made by manufacturing parts directly from the semi-finished state, with or without certain volumetric heat treatments and surface hardening, depending on the functional role and the physical-mechanical characteristics pursued. Some of these parts work in hydrodynamic conditions, where cavitation manifests itself through erosion, such as: propellers of boats and barges, pump rotors in water cooling systems of automobiles. Visual analyzes performed on sailboat and powerboat propellers, after identical durations and operating conditions, showed cavitation erosion damage, different depending on the type of aluminum alloy. As a result, the paper presents and analyzes the behavior and resistance to erosion by vibratory cavitation of 4 types of aluminum alloys in the state of rolled semi-finished products. To highlight the differences in the destruction of structures under the cyclic stresses of cavitational microjets, macro and microscopic images of the eroded structure are used, as well as the curves with the values of the parameters specific to cavitation, recommended by the ASTM G32 -2016 norms and used in the research laboratory's custom. The analysis of the results shows that the resistance of the structure to cavitation erosion is dependent on the type of alloy, the degree of brittle intermetallic compounds and the mechanical properties specific to toughness.