Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 2Citation - Scopus: 2Microstructural Evolution and Mechanical Performance of Dual-Phase Steels Under Fiber Laser Welding: Effects of Heat Input and Weld Penetration(Springer, 2025) Tuncel, Oguz; Davut, Kemal; Aydin, HakanThis study investigates the effects of fiber laser welding (FLW) parameters on the microstructural evolution and mechanical properties of DP800, DP1000, and DP1200 dual-phase steels, focusing on the role of heat input. Welding was performed using laser powers ranging from 1500 to 3000 W and welding speeds between 20 and 100 mm/s, resulting in heat inputs from 18 to 120 J/mm. Optimal welding conditions were identified as 55 J/mm for DP800, 120 J/mm for DP1000, and 53 J/mm for DP1200, which ensured full penetration and minimized HAZ softening. Detailed microstructural analysis using SEM and EBSD revealed significant transformations in the heat-affected zone (HAZ), including martensite degradation, grain coarsening, and tempered martensite formation, particularly in DP1200 steel, where hardness reductions reached up to 29%. Tensile tests demonstrated that while DP800 and DP1000 joints primarily failed within the base material (BM) with ductile fracture characteristics, DP1200 joints fractured within the HAZ due to a combination of brittle cleavage and ductile dimples caused by martensite breakdown and carbide precipitation. The findings underscore the necessity of optimizing welding parameters to control HAZ softening and preserve mechanical performance. By systematically analyzing the interplay between heat input, microstructure, and mechanical properties across different DP steel grades, this research provides a comprehensive understanding of how FLW conditions influence joint integrity, offering valuable guidance for designing robust welding strategies in advanced engineering applications.Article Citation - WoS: 5Citation - Scopus: 4Influence of Partitioning Treatment on Microstructure and Mechanical Properties of an Alloyed Ductile Iron Austempered at Different Temperatures(Walter de Gruyter GmbH, 2023) Neite, Maximilian; Münstermann, Sebastian; Nalçacı, Burak; Davut, Kemal; Erdoğan, MehmetThe present study was conducted to uncover effects of partitioning treatment on Cu-Ni-Mo alloyed ductile iron (DI) austempered at different temperatures. For this purpose, the DI samples, produced via sand casting, were austenitized at 900 °C for 60 min, followed by austempering at the temperatures of 275-325-375 °C for 120 min and afterwards a partitioning treatment was applied at 200 °C for 15 min. In the characterization studies, dilatometer, image analysis, JMat-Pro, mechanical tests, XRD, optical microscope, and scanning electron microscope (SEM) equipped with EBSD detector were utilized. Characterization studies showed that the effects of partitioning treatment were directly correlated with austempering temperature and high carbon austenite volume fraction changed in the range of 19.48-35.45%. That redistribution of carbon (C) between bainitic ferrite and high carbon austenite occurred, in turn, the carbon content of high carbon austenite increased with the partitioning treatment irrespective of austempering temperature were uncovered. Furthermore, the partitioning treatment considerably changed the grain morphologies of both high carbon austenite and banitic ferrite. As a consequence of these microstructural differences, the highest tensile strength of 1489.2 MPa was established in the sample austempered at 275 °C and partitioned at 200 °C, whereas the highest ductility of 5.61% acquired at the austempering temperature of 375 °C. © 2023 Walter de Gruyter GmbH, Berlin/Boston.Article Citation - WoS: 3Citation - Scopus: 3Nondestructive Microstructural Characterization of Austempered Ductile Iron(Walter de Gruyter GmbH, 2023) Tüzün, Mert Yağız; Yalçın, Mustafa Alp; Davut, Kemal; Kılıçlı, VolkanAustempered ductile iron (ADI) has been preferred in a wide range of applications due its unique combination of high strength, good ductility, wear resistance and fracture toughness together with lower cost and lower density compared to steels. Magnetic Barkhausen noise (MBN) measurement offers a better alternative to traditional characterization techniques by being fast and non-destructive. A simple linear regression using only one single independent variable cannot correlate the MBN with the microstructure of ADI, since its microstructure is multi component. Multiple linear regression analysis (MLRA) was used to build a model that uses the characteristic features of microstructural constituents as input parameters to predict the MBN. For that purpose, Cu-Ni-Mo alloyed ductile iron samples austempered between 325 and 400 degrees C and for 45-180 min duration were used. The results show that MBN is most sensitive to the size and shape of acicular ferrite and retained austenite. Moreover, MBN is almost insensitive to the size, morphology and volume fraction of graphite particles. This indicates that retained austenite pins the domain walls more effectively than the graphite particles. Considering the results MLRA, MBN technique can be used to characterize the ausferritic microstructure of ADI.Article Citation - WoS: 6Citation - Scopus: 6Texture Evolution of Friction Stir-Processed Dual-Phase Steel(Springer, 2022) Aktarer, Semih Mahmut; Küçükömeroğlu, Tevfik; Davut, KemalEvolution of crystallographic texture and local strains in different zones of a dual-phase steel subjected to severe plastic deformation by friction stir process was examined by electron backscatter diffraction technique. Misorientations, which were expressed by the values of grain orientation spread and kernel average misorientation (KAM), increased from the thermomechanical affected zone (TMAZ) to pin-affected stir zone (PE-SZ). KAM maps showed that the highest local strain appeared in the PE-SZ. Misorientation distributions were found to be consistent with microhardness distributions in the processed region. The crystallographic texture of base metal, heat-affected zone, and TMAZ was similar. Recrystallization and deformation texture components were observed at stir zones, and recrystallization texture components decreased drastically at PE-SZ. Rotated cube, goss and rotated goss texture components were detected at PE-SZ. Rotated cube texture component indicates partial recrystallization after plastic deformation. Shear texture components were determined using shear direction (SD) as reference. Different shear texture components (111), (112), and (101)