Inclusion Measurements in Al–Si Foundry Alloys Using Qualiflash and Prefil Filtration Techniques

Abstract

Qualiflash is a quick method of assessing the melt cleanliness of foundry Al–Si alloys over a wide range of Si contents up to 17 wt%. It has an immediate response in measuring the quantity of oxides and non-metallic inclusions. Improving the melt cleanliness moves the Quality Temperature Index line toward lower Q values. Prefil curves demonstrate very good sensitivities to the variations in the melt treatment conditions. The filtration rate is greatly affected by grain refiner addition. The highest curve is displayed by the alloy without grain refiner addition. The filtration rate progressively decreases with increasing amount of grain refiner. When the total amount of boron in the grain refiner added to the melt reaches 60 ppm, the filtration rate is approximately nil. The overall error on the Prefil curve is ± 9% at a level of confidence of 95% at any time during the filtration.