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Öğe Effect of Continuous and Pulsed Currents on Microstructural Evolution of Stainless Steel Joined by TIG Welding(Carl Hanser Verlag, 2015) Durgutlu, A.; Findik, T.; Gulenc, B.; Cevik, B.; Kaya, Y.; Kahraman, N.In this study, AISI 316L series austenitic stainless steel sheets were joined by tungsten inert gas welding method in continuous and pulsed currents. Regarding microstructural investigation and hardness values of weld metal, samples were welded to investigate the effect of current type on grain structures of weld metal. Results showed that samples welded by using pulsed current had considerable different properties compared to the samples welded by using continuous current. While the weld metals of joinings obtained by using continuous current displayed a coarse-grained and columnar structure, weld metals obtained by using pulsed current had a finer-grained structure. It was also found that hardness values of samples, which were welded with continuous and pulsed current, were quite different.Öğe An investigation into the effect of welding current on the plasma arc welding of pure titanium(Redakcia Kovove Materialy, 2010) Kahraman, N.; Taskin, M.; Gulenc, B.; Durgutlu, A.In the present study, plasma arc welding method was applied to commercial purity titanium using various welding current values. In order to determine the strength of the resulting joints, tensile tests, impact tests and hardness tests were applied. Additionally, optical microscopy examinations were carried out to determine the interface properties of the joints. The work showed that the highest interface strength was obtained for the specimens joined at 65 A. For all the welding parameters, the hardness test results showed that weld metal gave a higher hardness value than heat affected zone and base metal. The microstructure in welded joint consisted of acicular alpha and twins.Öğe An investigation into the effect of welding current on the plasma arc welding of pure titanium(2010) Kahraman, N.; Taskin, M.; Gülenç, B.; Durgutlu, A.In the present study, plasma arc welding method was applied to commercial purity titanium using various welding current values. In order to determine the strength of the resulting joints, tensile tests, impact tests and hardness tests were applied. Additionally, optical microscopy examinations were carried out to determine the interface properties of the joints. The work showed that the highest interface strength was obtained for the specimens joined at 65 A. For all the welding parameters, the hardness test results showed that weld metal gave a higher hardness value than heat affected zone and base metal. The microstructure in welded joint consisted of acicular alpha and twins.Öğe Joining of copper and steel plates by shielded metal arc and tig welding methods and investigation of their interface properties(2005) Durgutlu, A.; Kahraman, N.; Gülenç, B.In this study, low carbon steel and copper plates were welded to each other by shielded metal arc and tungsten arc welding processes. Mechanical and microstructural properties of the joints were investigated. Tensile, bending and hardness tests of the welded specimens were conducted. Optical microscopy and SEM studies were carried out, in order to make the microstructural evaluation. During the tensile tests of the welded specimens, fracture occurred in the copper side apart from the weld region. Macro examination of the bended specimens showed no crack and tears. The results showed that hardnesses of the shielded metal arc welded specimens were higher than those of tungsten arc welded samples. However, hardness values of the weld metal were found to be lower than those of the low carbon steel but it was found to be higher than those of the copper side. From the results of metallographic examination, a uniform transition from parent metal to weld metal was observed in the weld region and more grain growth was observed in TIG welding specimens due to higher heat input when compared to the shielded metal arc welded samples.Öğe A novel approach to diffusion bonding of copper to stainless steel(Sage Publications Ltd, 2012) Kaya, Y.; Kahraman, N.; Durgutlu, A.; Gulenc, B.In this study, austenitic stainless steel and copper materials were bonded through the diffusion welding method, one of the solid-state welding processes. The welding process was carried out at 875 degrees C temperature for 30 minutes under 3MPa pressure. Two different methods were employed in the welding process. In the first method, the conventional diffusion welding procedure was followed. In the second one, an external electrical current was applied to the parts to be joined with the help of a system that was added to the conventional system. By doing so, the aim was to determine the diffusion amount and length for the specimens obtained with and without current. The weld quality of the diffusion welded specimens was examined using the tensile and hardness test. In addition, microstructural analyses were done using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The highest hardness value was obtained in regions next to the interface and it was decreased gradually as the distance from the interface increased on both sides of the interface. The results indicated that the highest interface strength was obtained for the specimens joined when the external current was applied. According to the EDS and EDS line element analyses results, it can be seen that the specimens joined by applying the external current had a higher amount of diffusion and length than the specimens joined by the conventional technique.Öğe Production of wire reinforced composite materials through explosive welding(Elsevier Urban & Partner Sp Z O O, 2016) Gulenc, B.; Kaya, Y.; Durgutlu, A.; Gulenc, I. T.; Yildirim, M. S.; Kahraman, N.Explosive welding is a solid state welding process, which uses a controlled explosive detonation to force two metals together at high pressure. The process has been fully developed with large-scale applications in the manufacturing industry. The explosive bonding technique has an ability to bond a variety of similar and dissimilar materials, and has been applied to fabricate the clad materials and some composites such as multilayered and wire-reinforced materials. In this study, aluminum plates were explosively welded by placing a steel wire mesh between them in order to produce wire mesh reinforced composite materials. The steel wire meshes were placed at two different orientations (45 degrees and 90 degrees). The wire mesh was used to improve the mechanical properties of the explosively welded aluminum plates. Hardness, tensile strength, toughness, bending and microstructure of the explosively welded composite materials were evaluated. The tensile and toughness tests results showed that the 45 wire mesh reinforced composites exhibited higher strength than unreinforced explosively bonded Al plates. No separation was observed in the interface of the welded composite materials after three-point bending. The highest hardness value was measured for the area near the joining interface. (C) 2015 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved.Öğe Wear behaviour of crankshaft journals filled by submerged arc welding(Palladin Institute of Biochemistry of the NASU, 2014) Öztürk, A.A.; Gülenç, B.; Durgutlu, A.; Kahraman, N.In this study, wear behaviour of crankshaft journals filled by a submerged arc welding with different welding wires and powders is investigated. Hardness and microstructure variations in the submerged arc welding are examined. In addition, the amount of weight loss in abrasion samples of filling dry and lubrication ambience is measured under 40 N loads. It is observed that the amount of abrasion decreased with the increase of hardness at a certain point. Thin wire structure is provided for better abrasion resistance, and abrasion decreases with lubrication.
