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    The effect of cooling plate, mechanical vibration, and grain refinement on the microstructure and hardness of A380 produced by sand mold
    (Taylor & Francis Ltd, 2024) Uslu, Emin; Tigli, Ahmet; Colak, Murat
    The mechanical properties of aluminium alloys can be increased by controlling the grain size and morphology of the alloy. In these studies, mechanical vibration, cooling slope plate (CSP), and grain refiner were applied on sand mould casting using A380 alloys. The hardness, and microstructure of the cast samples are investigated. These processes lead to the refinement of grain structures and a decrease in the tendency for dendritic structure formation. The Effect of the solidification time (modulus) on the microstructure is investigated. It was determined that the solidification time varies depending on the section thickness, which affects the SDAS values. It was observed that the lowest SDAS values were in CSP and the highest values were in grain refiners added casting. The lowest hardness value was recorded at CSP casting. Meanwhile, the grain refiner added vibration casting exhibits the highest hardness.
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    Importance of Melt Cleaning Parameters on Reliability of Tensile Properties in A356 Alloy
    (Springer Int Publ Ag, 2025) Tigli, Ahmet; Uslu, Emin; Colak, Murat; Dispinar, Derya
    This study examines how melt treatment and pouring temperature affect the microstructure and mechanical properties of A356 aluminum alloy. Samples were cast under degassed, non-degassed, and upgassed conditions at 725, 750, and 775 degrees C. Melt quality was assessed using the reduced pressure test (RPT) and the bifilm index (BI), while microstructural features were analyzed via SEM and EDS. Tensile testing and Weibull statistics were used to evaluate mechanical performance and variability. Results showed that by improper degassing the reproducibility of mechanical properties decreased regardless of hydrogen content of the melt. When bifilm index (BI) was high (> 50 mm), the ductility was lowered and caused greater variability in strength and elongation. SEM confirmed large oxide films in samples, linked to the brittle fracture. The work also highlighted the importance of melt cleaning parameters for the reliability of cast aluminum alloys regardless of the hydrogen content.
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    Investigation of the effect of solidification time and Nb addition on the microstructure of A356 aluminum alloy castings
    (Gumushane University, 2024) Yalçin, Önder; Tokatli, M.; Tigli, Ahmet; Colak, Murat
    Aluminum alloys are very important engineering materials due to their lightness, corrosion resistance, high electrical and thermal conductivity, high strength, and ductility. Therefore; It is widely used in many areas such as automotive, aviation, defense, space industry, machinery manufacturing, and food industry. The demand for high-quality aluminum products is also growing as their applications increase. This study aims to explore the influence of adding 0.03%, 0.06%, and 0.1% niobium to the A356 aluminum casting alloy on the resulting microstructure. The investigation focused on permanent step mold casting with different cross-sectional profiles. In the study, melting, liquid metal cleaning (lance degassing), permanent mold casting, metallographic sample preparation, microstructure examination, and image analysis techniques were used. It was observed that SDAS and SDAL of A356 increased with decreasing cooling rate. With the addition of 0.1% Nb, the dimensions of SDAS demonstrated a reduction when contrasted with the as-received A356 castings. © 2024, Gumushane University. All rights reserved.