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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 Effect of temperature, force, and vibration on fatigue strength of friction stir-welded AA7075 aluminum alloy joints(SpringerLink, 2021-01-04) Çelik, Yahya Hışman; Kılıçkap, Erol; Çetkin, EdipIn this study, the AA7075 alloy pairs were welded by friction stir welding method by using conical- and triangular-type stirrer pins. Welding forces and moments, vibration, and temperature values have been measured during the jointing depending on the welding parameters. Finally, microstructures were examined and mechanical tests were carried out. Results obtained from the experiments revealed that at low spindle speed and welding feed rates, the temperatures formed on the surface of the alloy pair were high, the vibrations were low, and the welding force and moments were partially high. When the microstructures of the welded areas are examined, it was determined that the conical mixing pin has a better microstructure than the triangular mixing pin. In addition, it was determined that the mechanical properties of welded joints having a good microstructure were quite good. As a result, it was observed that forces during welding, temperature of welding, and vibration values have an effect on microstructure and mechanical properties.
