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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 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.
