Low pressure sand casting of ultrasonically degassed AlSi7Mg0.3 alloy: Modelling and experimental validation of mould filling

摘要

The effect of combining smooth mould cavity filling and ultrasonic degassing by using a low pressure sand casting process with US melt treatment on the microstructure and mechanical properties of AlSi7Mg0.3 alloy was investigated. Computational fluid dynamics (CFD) modelling and experimental validation was used to study the liquid metal flow behaviour and oxide film defect distribution for different filling rates, using two pressurization curves (p-t). The effect of ultrasonic degassing on the resultant microstructure (morphology and presence of porosities and inclusions) was studied for 650 and 700 ℃ melt degassing temperatures. Results show that ultrasonic degassing and mould filling velocities below 0.5 m/s improve the alloy microstructure and lead to high mechanical properties.