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    Investigation of Fe and Mn Effects on the Fluidity Behavior of A356 Aluminum Alloys
    (Polska Akademia Nauk, 2026) Çolak, M.; Alkan, N.; Kutsal, Ü.
    The fluidity behavior of Al–Si casting alloys is strongly influenced by impurity elements and intermetallic phase formation during solidification. In particular, iron (Fe) reduces melt fluidity by forming brittle Fe-rich intermetallics, whereas manganese (Mn) can mitigate this effect by modifying intermetallic morphology. In this study, secondary A356 aluminum alloys were produced with Fe contents of 0.10, 0.15, and 0.20 wt.% and nominal Mn additions of 0.05, 0.10, and 0.20 wt.% to investigate their combined effect on fluidity behavior. Melt quality was assessed using reduced pressure testing and density index measurements to ensure consistent casting conditions. Fluidity tests were conducted using spiral and eight-channel molds with section thicknesses ranging from 0.5 to 8 mm. To enable quantitative comparison across different section geometries, a Fluidity Index (FI) was defined based on section-normalized flow lengths. The results show that increasing Fe content generally reduces fluidity, while Mn additions significantly improve melt flow, with the most pronounced enhancement observed at 0.20 wt.% Mn. Thinner sections were found to be more sensitive to Fe-related flow restriction, whereas wider channels exhibited improved flow behavior. These findings demonstrate that appropriate Mn additions can effectively stabilize fluidity in secondary A356 alloys and provide practical guidelines for alloy control in recycled aluminum casting applications. © The Author(s) 2026. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)
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    Optimization of Rotary Degassing Parameters to Improve Melt Cleanliness and Mechanical Properties in A356 Aluminum Alloy
    (Polska Akademia Nauk, 2026) Kutsal, U.; Çolak, M.; Sağnak, Y.; Bardakci, S.; Ammas, G.; Sarper, G.
    Melt cleanliness is a critical factor that directly affects the quality of aluminum castings and becomes even more significant in recycling-oriented production, where high scrap utilization is inevitable. Increasing the proportion of scrap intensifies the risk of oxide films, inclusions, and gas porosity in the molten metal; therefore, efficient refining techniques are essential. In this study, the effects of rotary degassing parameters—including rotor speed, rotation time, and gas flow rate—on melt cleanliness of A356 aluminum alloy were systematically investigated. Experimental melts containing 20% primary and 80% scrap aluminum were treated under various degassing conditions using a commercial flux cleaning flux. Characterization was performed through the Reduced Pressure Test (RPT), bifilm index analysis, fluidity measurements, microstructural examinations, and mechanical testing (tensile test and Brinell hardness measurement). The results demonstrated that increasing the rotor speed from 200 rpm to 500 rpm significantly reduced both the density and bifilm indices, indicating a notable improvement in melt cleanliness. Furthermore, higher gas flow rate (10 L/min) and longer rotation time (10 min) provided additional but secondary improvements. Consequently, the optimization of rotary degassing parameters enhanced not only melt quality but also tensile strength and ductility. These findings offer practical insights for optimizing process control in recycling-based aluminum foundries. © The Author(s) 2026. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)