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Öğe Investigation of wear behaviours of Al matrix composites reinforced with different B4C rate produced by powder metallurgy method(Elsevier, 2017-09) Çelik, Yahya Hışman; Seçilmiş, KübraIn this study, the effects of wear behaviours of Al matrix composites reinforced with different B4C rate produced by powder metallurgy method were investigated. Al and B4C powders with purity of 99.9% and sizes of 25–44 µm were prepared as pure Al, 4% B4C/Al, 8% B4C/Al, 12% B4C/Al and 16% B4C/Al. After these prepared mixtures were pressed under 350 MPa, they were sintered for 90 min at 580 °C in atmospheric environment. Microhardness and wear tests of the produced samples were carried out. Wear experiments of these composites were performed with specially manufactured test equipment at different application loads (5 N, 10 N and 15 N), different sliding distances (250 m, 500 m, 750 m and 1000 m) and a constant speed of 0.46 m/s. In addition, optical microscope, SEM, EDS analyses were used to determine the microstructural changes in the worn and unworn surface of the manufactured composite materials. The results of experimental studies show that the increasing the B4C reinforced rate in composites with Al matrix has led to increase of the hardness and to reduce of the wear loss.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 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.
