Yazar "Colak, M." seçeneğine göre listele

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    Correlation Between K-value, Density Index and Bifilm Index in Determination of Liquid Al Cleanliness
    (Polska Akad Nauk, Polish Acad Sciences, 2023) Tigli, A.; Tokatli, M.; Uslu, E.; Colak, M.; Dispinar, D.
    Aluminum alloys are widely used in the industry thanks to its many advantages such as light weight and high strength. The use of this material in the market is increasing day by day with the developing technology. Due to the high energy inputs in the primary production, the use of secondary ingots by recycling from scrap material are more advantageous. However, the liquid metal quality is quite important in the use of secondary aluminum. It is believed that the quality of recycled aluminum is low, for this purpose, many liquid metal cleaning methods and test methods are used in the industry to assess the melt cleanliness level. In this study, it is aimed to examine the liquid metal quality in castings with varying temperature using K mold. A206 alloy was used, and the test parameters were selected as: (i) at 725 & DEG;C, 750 & DEG;C and 775 & DEG;C casting temperatures, (ii) different hydrogen levels. The hydrogen level was adjusted as low, medium and high with degassing, as-cast, and upgassing of the melt, respectively. The liquid metal quality of the cast samples was examined by the K mold technique. When the results were examined, it was determined that metal K values and the number of inclusions were high at the as-cast and up-gas liquid with increasing casting temperatures. It has been understood that the K mold technique is a practical method for the determination of liquid metal quality, if there is no reduced pressure test machine available at the foundry floor.
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    Investigation of the Effect of Solidification Time and Addition Amount of Inoculation on Microstructure and Hardness in Lamellar Graphite Cast Iron
    (Polska Akad Nauk, Polish Acad Sciences, 2022) Colak, M.; Uslu, E.; Teke, C.; Safak, F.; Erol, O.; Erol, Y.; Coban, Y.
    Material suppliers typically recommend different additive amounts and applications for foundry practices. Therefore, even in the production of the same standard materials, different results may be obtained from various production processes on different foundry floors. In this study, the liquid metal prepared with the addition of different proportions of a FeSi-based inoculation, which is most commonly used in foundries in the production of a cast iron material with EN-GJL-250 lamellar graphite cast iron, was cast into sand molds prepared with a model designed to provide different solidification times. In this way, the optimization of the inoculation amounts on the casting structure for different solidification times was investigated. In addition, hardness values were determined depending on solidification time in varying amounts of inoculation additions. SolidCast casting simulation software was used to determine the casting model geometry and solidification time. In the scope of the study, sand casting, modeling, microstructure analysis, image analysis, microstructure analysis, and hardness tests techniques were used. When the results are examined, the required amount
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    Modeling of the Impact of Initial Mold Temperature, Al5Ti1B and Al10Sr Additions on the Critical Fraction of Solid in Die Casting of Aluminum Alloys using Fuzzy Expert System
    (Polish Acad Sciences Inst Physics, 2019) Teke, C.; Colak, M.; Tas, M.; Ipek, M.
    In the casting of liquid metal, the feeding stops when the mushy zone is clogged and does not allow the transfer of feeding liquid. The growing resistance of the solid dendrites against the fluidity of the feeding liquid is defined as the critical fraction of solid (CFS). CFS value varies depending on many factors such as alloy solidification range, initial mold temperature, and the grain size. Therefore, in many casting simulation applications, it is quite common to get inconsistent results due to insufficient information about the CFS. In this study, a fuzzy expert system (FES) model has been developed in order to determine the value of the CFS in the die casting process, based on the parameters of the alloy type, the initial mold temperature, Al5Ti1B addition and Al10Sr addition. In order to create the rule base for the FES model, 54 die casting experiments have been carried out. The CFS values obtained using the FES model has revealed that the developed model of the FES predicts the CFS value in a high performance.
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    Prediction of critical fraction of solid in low-pressure die casting of aluminum alloys using artificial neural network
    (Sharif Univ Technology, 2019) Teke, C.; Colak, M.; Kiraz, A.; Ipek, M.
    Casting simulation programs are computer programs that digitally model the casting of an alloy in the sand, shell, or permanent mold and, then, the cooling and solidification processes. However, obtaining consistent results out of casting modeling depends on the incorporation of many accurate parameters and boundary conditions. Critical Fraction of Solid (CFS), which is one of the most important of these parameters, is defined as the point where solid dendrites do not allow any flow of the liquid metal in the mushy zone. Since the CFS value varies based on many factors, inconsistent results can be experienced in the modeling applications. In this study, the CFS value obtained during the solidification of various commercial aluminum alloys' casting process, carried out using low-pressure die casting method, is predicted by using Artificial Neural Network (ANN) method based on alloy type, grain refiner and modifier additions, initial mold temperature, and pressure level parameters. In the scope of the study, 162 experiments are conducted. The results obtained from the low-pressure die casting experiments using a special model designed for the study are validated by using SOLIDCast casting simulation. The CFS values are obtained in this validation range of 33% to 61%. These CFS values are used in the development of ANN models. Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Mean Square Error (MSE) are used to assess the prediction accuracy of the ANN models. Calculated values of MAE, MAPE, and MSE are 0.0188, 7.06%, and 0.0006, respectively. The results show that the proposed ANN model predicts a CFS value with high accuracy. (C) 2019 Sharif University of Technology. All rights reserved.
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    Role of Metal Quality and Porosity Formation in Low Pressure Die Casting of A356: Experimental Observations
    (Polska Akad Nauk, Polish Acad Sciences, 2021) Gursoy, O.; Nordmak, A.; Syvertsen, F.; Colak, M.; Tur, K.; Dispinar, D.
    Porosity is one of the major problems in casting operations and there are several discussions in the literature about the porosity formation in aluminum castings. Bifilms are the defects that are introduced into the melt by turbulence. They can be detected with reduced pressure test and presented numerically by measuring bifilm index. The measure of bifilm index is the sum of total oxide length given in millimeters from the cross-section of reduced pressure test sample solidified under 0.01 MPa. In this work, low pressure die casting (LPDC) unit was built in an attempt to enhance the producibility rate. The unit consists of a pump housing that was placed inside the melt in the melting furnace where the pressure was applied instead of the whole melt surface. It was observed that the melt quality of A356 alloy was deteriorated over time which had led to higher porosity. This was attributed to the increased oxide thickness of the bifilm by the consumption of air in between the folded oxides. A relationship was found between bifilm index and pore formation.