Ahmed Osman, Naser A. Alsaleh, Mahmoud Ahmadein, Mahmoud A. El-Sayed
A parametric study was performed to explore the effect of runner thickness, filtration, and hydrogen content on the mechanical properties and defect formation in Al-7%Si–0.3%Mg (2L99) sand castings. A two-level full factorial design of experiments was used to statistically evaluate these parameters and the tensile properties were characterized via Weibull distribution analysis. The findings reveal that decreasing the runner thickness from 25 mm to 10 mm and using 10 PPI ceramic filters improve mechanical properties by minimizing double oxide film entrainment as confirmed by electron microscopy examination. In addition, lowering hydrogen concentrations within the Al alloy from 0.24 cm3/100 g Al to 0.12 cm3/100 g Al is also shown to enhance casting integrity by suppressing bifilm inflation and subsequent pore formation. ANOVA results indicate that the hydrogen content is the most important factor, contributing 53% to the variability in mechanical properties, followed by filtration (25%) and runner thickness (17%). The optimized casting conditions including thin runners (10 mm thick), melt filtration, and a low hydrogen level (0.12 cm3/100 g Al), result in an approximately 474% increase in the shape factor and a 107% increase in the characteristic life of UTS, as well as an approximately 413% increase in the shape factor and a 149% increase in characteristic life of elongation. The outcomes suggest that controlled filling systems and melt treatment are critical for producing consistent, high integrity aluminum castings in industrial applications.