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Öğe The Effect of Ageing Temperature in T6 Heat Treatment on Mechanical Properties of AA7075(Polish Acad Sciences Inst Physics, 2019) Simsek, I.; Simsek, D.; Tuncay, T.; Ozyurek, D.In this study, the effect of ageing temperatures in T6 heat treatment on the microstructural changing and mechanical properties of AA7075 were investigated. The samples were quenched after solution treatment at 485 degrees C for 2 h. The natural ageing was applied for 1 h, and then artificial ageing was carried out at five different temperatures (100-140 degrees C) for 24 h. Hardness measurements, microstructure, X-ray diffraction examinations, and tensile tests of aged samples were carried out. As a result of the study, the hardness values and ultimate tensile stress values were increased by increasing ageing temperatures up to 120 degrees C. Then it was decreased by increasing ageing temperature. Ultimate tensile stress values were compatible with hardness values and maximum ultimate tensile stress values were obtained in aged samples at 120 degrees C.Öğe The effect of the aging time on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment(G.V. Kurdyumov Institute for Metal Physics of N.A.S. of Ukraine, 2019) Simsek, I.; Simsek, D.; Ozyurek, D.; Tekeli, S.In this study, the effect of the aging time on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment is investigated. The AA7075 alloys are quenched after solid solution treatment at 485°C for 2 hours and artificially aged at 120°C using five different aging times. Hardness measurements, microstructure examinations (SEM + EDS, XRD), and tensile tests are performed for the aged alloys. Fractured surfaces are also examined using SEM images after the tensile testing. The results of the studies conducted show that the hardness value of the alloys can be increased by increasing aging time, and the maximum hardness value of 192 HV is obtained for the alloy aged for 25 hours. Tensile tests also show that the tensile strength of the alloy can be increased by increasing aging time, and the maximum tensile strength value of 580 MPa is obtained for the alloy aged for 25 hours. Fractured surface examinations revealed that the ductile fracture mechanism is mostly dominant, while the planar fracture mechanism is observed as well. © 2019 G. V. Kurdyumov Institute for Metal Physics, National Academy of Sciences of Ukraine.Öğe Investigation of the Effect of Ni Amount on the Wear Performance of A356 Cast Aluminum Alloys(Springer, 2020) Simsek, I.; Simsek, D.; Ozyurek, D.This study investigates the effect of artificial aging treatment on wear performance of A356 alloy containing different amounts of Ni. Within the scope of the study, A356/Ni alloys were produced using the sand mold casting method and then the artificial aging treatment was applied. Alloys were naturally aged at room temperature for 24 hours and artificially aged at 170 degrees C for 10 hours after keeping in solid solution for 8 hours at 540 degrees C and rapidly cooling. The alloys produced were characterized with hardness and density measurements, microstructure examinations, and X-ray diffraction. Wear tests were performed using a pin-on-disc type testing device under three different loads and at four different sliding distances. It was found that alloy density increases with increasing Ni amount. The highest hardness value was obtained for 1% Ni added alloy, and an increase in hardness was observed with the addition of Ni. The lowest weight loss was obtained for 1% Ni added alloy, which also had the highest hardness, and it was observed that the addition of Ni led to an increase in weight loss.Öğe Optimizing of Wear Performance on Elevated Temperature of ZrO2 Reinforced AMCs Using Weighted Superposition Attraction Algorithm(National Institute of Science Communication and Policy Research, 2022) Simsek, D.; Ozyurek, D.; Ileri, E.; Akpinar, S.; Karaoglan, A.D.In the current study, the zirconium oxide (ZrO2) reinforced Aluminium Matrix Composites (AMCs) was designed as a brake lining and produced by mechanical alloying (MA) method. Wear tests of AMCs were performed according to ASTM G-99 at different sliding distance, operating temperatures and load in the range of 53 to 94 m, 20 to 340? and 10 to 30 N respectively. Optimum wear performance parameters were determined using the Weighted Superposition Attraction (WSA) algorithm. Firstly, to formulize the problem as an optimization problem through the guidance of the regression modelling, an experimental design has been constructed, and the wear tests have been done at different reinforced rates, operating temperature and loads. Secondly, WSA algorithm has been adapted to tackle the formulated optimization problem. According to the results of WSA algorithm, the optimum rate of zirkonium oxide (ZrO2), load and operating temperature was determined as 12%, 206.33°C and 21.20 N respectively while keeping the friction coefficient between 0.15–0.24. © 2022 Scientific Publishers. All rights reserved.Öğe Relationship between Al2O3 Content and Wear Behavior of Al+2% Graphite Matrix Composites(De Gruyter Poland Sp Z O O, 2020) Simsek, D.; Simsek, I; Ozyurek, D.In this study, the microstructure and wear behaviours of aluminium composites, reinforced with different amounts of (3-12%) Al2O3 and 2% (% vol.) graphite were investigated. The Al2O3 and graphite were added to Al matrix and mechanically alloyed for 60 minutes. Subsequently, the mechanically alloyed powders were pressed under 700 MPa pressure and sintered at 600 degrees C for 120 minutes. The produced aluminium composites were characterized by microstructure, scanning electron microscope (SEM), X-ray diffraction (XRD), density and hardness measurements. Afterwards, wear tests were carried out on a block on-ring type wear testing device, under three different loads and four different sliding distances. As a result, the hardness and density of composites were observed to increase due to the increase in the amount of reinforcement in aluminium composites. The highest hardness and density values were obtained in composite material containing 12% Al2O3. The wear tests, the lowest weight loss was also obtained in composite containing 12% Al2O3.
