Yazar "Ayhan, Ismail Irfan" seçeneğine göre listele

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    A comparative assessment of artificial neural network and regression models to predict mechanical properties of continuously cooled low carbon steels: an external data analysis approach
    (2024) Alan, Emre; Ayhan, Ismail Irfan; Ogel, Bilgehan; Uzunsoy, Deniz
    In this study, mechanical properties of continuously cooled low carbon steels were predicted via Artificial Neural Network (ANN) and Multiple Linear Regression (MLR) models. Unlike the previous studies, laboratory scaled self-generated data that consists of chemical compositions and cooling rates were used as input while yield strength (YS), ultimate tensile strength (UTS) and total elongation (TE) were served as target data. The prediction performances of the models were compared by applying new data set extracted from external sources like previously studied research papers, thesis or dissertations. A better agreement between predicted and actual data was achieved with ANN model. Additionally, the response of ANN model to new external data resulted in lower prediction errors even the data has one or more input value that is not included in the range of training data set. Unlike ANN model, MLR model shows a significant decrease in prediction accuracy when input data has non-uniform distribution or target data takes place in relatively narrow range. In general, it was shown that ANN model trained with self-generated data can be used as an efficient tool to estimate mechanical properties of continuously cooled low carbon steels that are produced with various conditions, even for the phenomena between input and output is complex and data distribution is non-uniform.
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    Effect of Double Austenitization and Pre-Annealing Heat Treatment on the Microstructural and Mechanical Properties of QT 41Cr4 Steel
    (Springer India, 2023) Celtik, Cansu; Ayhan, Ismail Irfan; Yurekturk, Yakup
    In this study, the effect of double austenitization and pre-annealing heat treatment on the final microstructure concerning changes in hardness, strength, impact toughness and hardenability characteristics of 41Cr4 steel has been examined in comparison with conventional quenching-tempering treatment. The microstructural changes were characterized by an optical microscope (OM) and scanning electron microscope (SEM), and also the variations in austenite grain sizes and carbide sizes were estimated with the Image J program. The results indicated that precursor microstructures formed with quenching and also subcritical annealing tailored the prior austenite grains and carbides in a manner of improving the strength and toughness without loss in hardness and ductility. 776 MPa yield strength and 30 J Charpy impact energy were obtained in conventional quench-tempering settings, and the corresponding values for double austenitization treatment were 886 MPa and 71 J, and 830 MPa and 34 J for pre-annealing treatment, respectively. Grain size reduction and modification of carbides in tempered martensite microstructure with the applied pre-heat treatments resulted in advanced Charpy impact energies including cryogenic test circumstances and room temperature strength values.