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Öğe EFFECT OF WIRE ELECTRICAL DISCHARGE MACHINING ON THE SURFACE OF EBM-ADDITIVE MANUFACTURED NITI ALLOYS(2021) Peduk, Gozde Sultan Altug; Dilibal, Savaş; Gürol, UğurNickel-titanium (NiTi) shape memory alloys are used in varied engineering products, such as biomedical device and mechatronic actuator applications. The conventional machining technology are utilized in the limited fields due to their effects on the hardness and brittleness of the machined alloys. However, the wire electrical discharge machining (WEDM) technology is one of the most preferred post-processing tool to obtain a surface with high quality. The electrical current and voltage values with pulse on and pulse off time are the crucial parameters for WEDM. These parameters should be optimized before wire electrical discharge machining process. Electron beam melting (EBM)-based additive manufacturing of the nickel-titanium powders provides obtaining bulk NiTi shape memory alloys using high energy electron beams. In this study, the application of WEDM which is used as a post-processing tool is evaluated for the EBM-based additive manufactured NiTi samples. Additionally, the scanning electron microscopy results of the wire electrical discharge machined NiTi samples are carefully investigated.Öğe HEAT INPUT EFFECT OF THE FCAW PROCESS ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF STRUCTURAL STEEL JOINTS(2022) Gürol, UğurFlux-cored wires are commonly used in structural and pipeline welding, shipbuilding, offshore constructions, and petrochemical and power generation industries. The higher heat inputs in the multipass welding result in shorter production time while considerably changing the properties of the welded joint. In this study, robotic flux cored arc welding with varying heat inputs (between 0.56-2.52 kJ/mm) was performed to determine the effect of heat input on weld microstructure, hardness, tensile properties, and impact toughness in the structural steel joints. Results exhibited that decrease in heat input from 2.52 to 0.56 kJ/mm changed the majority of the microstructure from polygonal ferrite to acicular ferrite. Furthermore, this increased by 56%, 37%, and 47% in yield strength, tensile strength, and hardness values, respectively, while decreasing by 30% and 15% in elongation and Charpy impact test results, respectively. Moreover, all welded joints displayed a satisfying toughness value higher than the requested value of 47 J, even at the test temperature of -50 °C. Finally, it can be concluded that the optimum results were obtained with a heat input of 1.26 kJ/mm, considering the minimum requirements of the AWS A5.20 standard and the expectations in applications.Öğe MANUFACTURING AND CHARACTERIZATION OF WAAM-BASED BIMETALLIC CUTTING EQUIPMENT(2022) Gürol, Uğur; Dilibal, Savaş; Turgut, Batuhan; Baykal, Hakan; Kümek, Hülya; Koçak, MustafaWire-arc additive manufacturing (WAAM) is a promising method to produce many functional components in different industries. In this method, the welding wires from the feedstock are melted by arc discharge and deposited layer by layer. Other welding wires having different chemical compositions can also be added to the top of the previously deposited layer by replacing the feed wire from the stock to produce bimetallic components. This study investigated the feasibility of using robotic wire arc additive manufacturing technology to produce a bimetallic cutting tool. The bimetallic cutting tool was produced by depositing MSG 6 GZ-60 hard-facing welding wire on top of the austenitic stainless-steel wall produced with ER 316LSi solid wire. The cutting-based equipment requires an increased abrasion resistance with the combination of ductility to provide adequate tool life and performance. Thus, detailed microstructural analysis and hardness tests were conducted to understand the general microstructural characteristic of the manufactured cutting tool, including interfaces between two different materials.Öğe Microstructural and mechanical characterizations of weld metal of S960QL ultra high strength steel joints obtained with different multi-pass laying techniques using GMAW(Institute of Physics, 2024) Mert, Tolga; Gürol, Uğur; Tümer, Mustafa15 mm thick ultra-high strength steel plates with 960 MPa yield strength were welded using different multi-pass laying techniques (i.e., stringer and weaving beads) with torch manipulation. Weld metals obtained were compared using different mechanical (i.e., micro tensile tests and Vickers hardness maps) and microstructural (i.e., optical microscope, scanning electron microscope, x-ray diffraction, electron backscatter diffraction) characterization techniques. Coarser grains and acicular ferrite were observed in weld metal obtained with the weaving pass procedure. There were hardness differences in the face and root passes of both weld metals. Yet, hardness values were 19% and 11% higher for the face and root regions of the joint obtained by stringer pass procedure, respectively. Fractographs of micro tensile test specimens revealed dimples depicting ductile network structure for both joints.Öğe Sualtında Birleştirilen AH36 Gemi Sacının Mikro Yapı ve Mekanik Özelliklerinin İncelenmesi(2023) Yıldız, Nur Benuşe; Gürol, Uğur; Baykal, Hakan; Koçak, MustafaBu çalışmada, örtülü elektrot ark kaynağı yöntemi ile yerli E6013 rutil elektrotlar (GeKaTec UW E6013) kullanılarak gemi imalat sektöründe; gemilerin gövdesinde ve tankların yapımında yaygın olarak kullanılan AH36 çelik plakaları su altında alın alına birleştirilmiştir. Kaynak işlemleri gerçek deniz ortamında 4 metrelik bir derinlikte uzman sanayi dalgıçları tarafından gerçekleştirilmiştir. Plakalar ilk olarak AWS D3.6 standardının gerekliliklerine uygun olarak tahribatsız muayene testlerine tabi tutulmuştur. Daha sonra su altında birleştirilen kaynaklı plakaların mekanik özelliklerini belirlemek amacıyla sertlik, çentik darbe, eğme ve çekme testleri uygulanmış olup, sonuçlar kaynak bölgesinde meydana gelen mikro yapısal dönüşümlerle birlikte yorumlanmıştır.Öğe YÜKSEK MUKAVEMETLİ BALİSTİK ZIRH ÇELİKLERİNİN KAYNAKLANABİLİRLİĞİ(2023) Çelik, Ceren; Göçmen, Müesser; Çoban, Ozan; Baykal, Hakan; Gürol, Uğur; Koçak, MustafaSavunma sanayisinin zırhlı araçları için geliştirilen düşük alaşımlı yüksek mukavemetli zırh çeliklerinin ark kaynak teknolojisi uygulamaları metalurjik bilgi ve deneyim isteyen zor uygulamalardır. Bu çeliklerin yüksek karbon eşdeğeri ve yüksek mukavemeti sağlayan martenzitik mikroyapıları nedeniyle kaynak proseslerinde güçlüklerle karşılaşılmaktadır. Seçilecek kaynak telinin yüksek süneklilik kapasitesi olan östenitik ya da yüksek mukavemetli olan ferritik yapıda olması kaynak metalinin sahip olacağı mekanik özellikleri ve kaynaklı bağlantının balistik özelliklerini belirlemektedir. Bu seçimler, doğası gereği kaynak parametrelerini ve proses adımlarını da farklılaştırmaktadır. Bu çalışmada; zırh çeliklerinin sınıflandırılması ile kaynak yönteminin, kaynak konfigürasyonun, kaynak metalinin, ısı girdisinin, ısıl işlem uygulamalarının ve gerçekleşen ısıl çevrimlerden dolayı elde edilen mikroyapısal değişimlerin mekanik ve balistik özelliklere etkileri tartışılmıştır.