Influence of Flux Composition on Melt Cleanliness and Fluidity in Secondary AlSi7Mg0.3 Alloys

This study presents an experimental and exploratory evaluation of the influence of flux composition on the melt quality and casting fluidity of secondary AlSi7Mg0.3 aluminum alloys. Four distinct melt conditions were investigated, including a flux-free reference and three flux compositions based on MgCl2-KCl with varying NaF-KF additions. Melt quality was assessed through Density Index (DI) and K-mold inclusion tests, while casting behavior was evaluated using both a spiral and a four-strip sectioned (2-8 mm) fluidity molds. The results showed that optimized flux composition led to a significant reduction in DI-6.31-1.21% and in K-values-2.6 to 0.4-indicating effective hydrogen degassing and oxide removal. These improvements translated into a spiral fluidity increase from 58 to 177 mm (approximate to 205%), and a 400% enhancement in 2 mm strip flow length, demonstrating a direct link between melt cleanliness and casting fill performance. A multivariate regression model relating DI and K-values to spiral fluidity yielded a determination coefficient of R2 approximate to 0.85 with a mean absolute percentage error (MAPE) of 12.49%, supporting the potential for integrated quality prediction even with a limited dataset. Although exploratory in nature, the findings emphasize the critical role of flux composition in improving both internal melt integrity and functional casting outcomes. The study also highlights the diagnostic potential of four-strip sectioned mold, rarely addressed in the literature, as a sensitive indicator of melt behavior in geometrically constrained conditions. The integrated approach presented here offers a practical framework for optimizing flux selection and evaluating melt quality in secondary aluminum casting processes.

Dergi

INTERNATIONAL JOURNAL OF METALCASTING

Yıl

2026

ISSN

1939-5981

eISSN

2163-3193

DOI

10.1007/s40962-026-01918-2

WoS UID

WOS:001719069700001