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Öğe Effect of welding parameters on microstructure and mechanical properties of AA7075/AA5182 alloys joined by TIG and MIG welding methods(SpringerLink, 2020) Çelik, Yahya Hışman; Temiz, Şemsettin; Çetkin, EdipIn this study, V and X welding grooves were opened to the forehead positions of the AA5182 and AA7075 aluminum alloy pairs and these alloy pairs were joined with tungsten inert gas (TIG) and metal inert gas (MIG) methods. Three diferent welding currents were used in joints. Gas fow rates of 12 and 17 l/min at the TIG welding and wire feed rates of 38 and 45 cm/min at MIG welding were selected. The efect of the welding grooves, welding current, gas fow rate and wire feed rate on microstructure and mechanical properties were investigated. Microstructures of welding zones were analyzed by an optical microscope and a scanning electron microscope (SEM). Vickers hardness of these zones was also measured. In addition, tensile and fatigue tests were carried out. Fracture mechanisms of failed specimens were conducted after the tensile tests were examined by using SEM. The highest hardness, tensile and fatigue strengths were obtained from the alloy pairs joined by opening X welding groove with TIG welding method. These values were 89 HV, 262.87 MPa, and 131.5 MPa, respectively. Similarly, the lowest tensile and fatigue strengths were obtained from the alloy pairs joined by opening V welding groove in the TIG welding method. These values were, respectively, 94.48 MPa and 19.1 MPa. However, the minimum hardness value was measured as 58 HV from the alloy pairs joined by opening V welding groove with MIG welding methods. In addition, it was observed on the fracture surfaces that the grain distributions and mechanisms difered depending on the welding methods, welding groove, and welding parameters.Öğe Repair of an aluminum plate with an elliptical hole using a composite patch(Carl Hanser Verlag, 2018-11-15) Ergün, Raşit Koray; Adin, Hamit; Şişman, Abdullah; Temiz, ŞemsettinIn this paper, the stress on axially loaded metal sheets with elliptical holes reinforced by a double-sided composite patch was analysed. The metal sheets with elliptical holes were subjected to axial loading, although no load was applied along the edges of the holes. The central elliptical holes on the metal plates had different diameters. The overlap distance of composite patches, which were adhesively bonded on each side, was of varied lengths. Elasto-plastic stress analyses were examined by means of the finite element method (FEM). The experimental results were compared with numerical results and a convergence rate of 92 % was achieved.Öğe A research on the fatigue strength of the single-lap joint joints bonded with nanoparticle-reinforced adhesive(Welding in the World, 2021-01) Adin, Hamit; Saraç, İsmail; Temiz, ŞemsettinNano-technological developments, which have made significant progress in recent years, have significant impact on the science of adhesives. Therefore, in our study, the static and fatigue strengths of single-lap joints (SLJs) incorporating nanoparticles were compared to those without nanoparticles. Steel plates were used in the adhesive joints. The results revealed that average damage load increased significantly in nanoparticle-reinforced adhesive joints. The highest damage load was obtained with 4 wt% nanoAl2O3 in epoxy adhesive. As the average damage load increased, the locus of damage changed from interfacial to the mixture of interfacial and cohesive. Also, fatigue strengths of the joints increased when the adhesive joint had nano-Al2O3 and nano-SiO2, and decreased when the adhesive joint had nano-TiO2.Öğe Microstructure and mechanical properties of AA7075/AA5182 jointed by FSW(Journals & Books, 2019-06) Çelik, Yahya Hışman; Çetkin, Edip; Temiz, ŞemsettinIn this study, AA7075 and AA5182 aluminium alloys were joined using different rotation speeds (980, 1325 and 1800 rpm), feed rates (108 and 233 mm/min) and stirred pins having two different geometries (conical helical and triangular). Microstructures of welding joints were examined by an optical microscope and a scanning electron microscope (SEM). Vickers hardness measurements were performed in the welding zone of samples removed from each welded plate. Tensile and fatigue tests were also applied to the test specimens taken from the welded plates. After the tensile tests, the surface fractures and possible welding defects were scanned via SEM. The best mechanical properties were obtained when conical helical shape stirrer pins were used. The values were 265 MPa for tensile test and 159 MPa for fatigue test. The hardness value was very close to each other and varied depending on the rotation speed. The highest hardness value was determined as 87 HV in the weld center at 1325-rpm rotation speed.Öğe Experimental and numerical strength analysis of double lap joints subjected to tensile loads(Materials Testing, 2014) Adin, Hamit; Temiz, ŞemsettinIn this paper the mechanical behaviour of double lap joints (DLJs) bonded with adhesive was analyzed. The stress-strain behaviour was investigated along the overlap length and adherend thickness in DLJs subjected to tensile loads. The stress analyses were performed by finite element method (FEM). The FEM calculations were performed using ANSYS (12.0.1). Experimental results were compared with the FEM results and were found to be quite reasonable. The results show that the failure loads are increased with an increase in adherend thickness. The stress-strain behaviour changes depending on adherend thickness and overlap length. Both FEM stress analyses and experimental results revealed that failure occurred around the edge zones of the overlap length due to the effect of shear stresses, while the failure at the edges of the adhesive layer originated from the peel stress in tensile.Öğe Investigation of the effect of use of Nano-Al2O3, Nano-TiO2 and Nano-SiO2 powders on strength of single lap joints bonded with epoxy adhesive(Elsevier, 2019-06) Adin, Hamit; Temiz, Şemsettin; Saraç, İsmailIn this study, single lap joints were formed by adding nano-Al2O3, nano-TiO2and nano-Al2O3powders in variousproportions to the epoxy adhesive and using the additive-free epoxy adhesive; and also the mechanical prop-erties of the connections were experimentally investigated at 20, 25, 30, 50 and 70 mm overlap lengths undershear load. In the experimental work, DP460 epoxy adhesive was used as adhesive and AISI 304 stainless steelplate as adherent material. When the results obtained from the experiments were examined, it was revealed thatthe average damage load in connection with the use of nanoparticle-added adhesives increased considerably ingeneral. As a result of the experiments, the most effective nanoparticle in increasing the failure strength of theadhesive joints with nano-Al2O3particles and the maximum failure strength increase rate was 20 mm in overlaplength and 97% in 4 wt% nano-Al2O3reinforced specimens. It was also found that the nanoparticle strain was animportant parameter in the tensile strength of the adhesive joints. In addition, it has been found that the additionof nanoparticles into the adhesive increases the elongation of the joints. When the adhesion surfaces of thesamples were examined as in the case of plain adhesives, damage was observed as adhesion separation whilenanoparticle reinforcement was observed as a mixture of adhesion and cohesion.Öğe Microstructure and mechanical properties of AA7075/AA5182 jointed byFSW(Elsevier, 2019-06) Çetkin, Edip; Çelik, Yahya Hışman; Temiz, ŞemsettinIn this study, AA7075 and AA5182 aluminium alloys were joined using different rotation speeds (980, 1325 and 1800 rpm), feed rates (108 and 233 mm/min) and stirred pins having two different geometries (conical helical and triangular). Microstructures of welding joints were examined by an optical microscope and a scanning electron microscope (SEM). Vickers hardness measurements were performed in the welding zone of samples removed from each welded plate. Tensile and fatigue tests were also applied to the test specimens taken from the welded plates. After the tensile tests, the surface fractures and possible welding defects were scanned via SEM. The best mechanical properties were obtained when conical helical shape stirrer pins were used. The values were 265 MPa for tensile test and 159 MPa for fatigue test. The hardness value was very close to each other and varied depending on the rotation speed. The highest hardness value was determined as 87 HV in the weld center at 1325-rpm rotation speed.
