Issue 43

M. Tocci et alii, Frattura ed Integrità Strutturale, 43 (2018) 218-230; DOI: 10.3221/IGF-ESIS.43.17 218 Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases Marialaura Tocci, Annalisa Pola, Lorenzo Montesano , G. Marina La Vecchia Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123, Brescia, Italy m.tocci@unibs.it , http://orcid.org/0000-0002-7515-0615 annalisa.pola@unibs.it , http://orcid.org/0000-0002-0722-6518 lorenzo.montasano@unibs.it , http://orcid.org/0000-0001-5465-6265 marina.lavecchia@unibs.it, http://orcid.org/0000-0001-5919-0396 A BSTRACT . In the present paper, the influence of eutectic and intermetallic phases on cavitation resistance of Al-Si alloys was studied. In fact, Al-Si alloys are commonly used for the production of components, such as cylinders, pistons, pumps, valves and combustion chambers, which in service may incur in cavitation phenomenon. Samples of AlSi3, AlSi9 and AlSi9CuFe were characterized from the microstructural point of view. Hardness measurements were also performed. Subsequently, cavitation tests were carried out according to ASTM G32 standard and the erosion mechanism was examined by scanning electron microscope. It was found the both eutectic and intermetallic phases enhance cavitation resistance, expressed in terms of mass loss. Particularly, intermetallic particles with complex morphologies provide a positive contribution, exceeding that of other microstructural features, as grain size. The effect of T6 heat treatment was also evaluated. It was confirmed that the precipitation of fine strengthening particles in the Al matrix successfully hinders the movement of dislocations, resulting in a longer incubation stage and a lower mass loss for heat-treated samples in comparison with as-cast ones. Finally, the relationship between cavitation resistance and material hardness was investigated. K EYWORDS . Cavitation erosion; Scanning Electron Microscopy; Al-Si alloys; Brinell hardness; Intermetallics. Citation: Tocci, M., Pola, A., Montesano, L., La Vecchia, G. M., Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases, Frattura ed Integrità Strutturale, 43 (2018) 218-230. Received: 15.11.2017 Accepted: 06.12.2017 Published: 01.01.2018 Copyright: © 2018 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION avitation erosion is a mechanical damage that occurs when a component is in contact with a liquid in particular pressure conditions [1] since gas or vapor bubbles can nucleate and subsequently collapse due to pressure fluctuations in the fluid. The energy associated to this bubbles collapse is significant and it can cause remarkable stress on the surface of the metallic component located in the surrounding areas [2]. In fact, these violent collapses produce C