MCBÜ Açıkerişim Sistemi :: Browsing by Subject "Aluminum alloys"

Browsing by Subject "Aluminum alloys"

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Mechanical properties and wear strengths in aluminiumalumina composites
(RILEM Publications, 1998) Atïk E.
In this study, after producing metal matrix composite materials reinforced with ceramic particles by adding hard Al2O3 particles into a selected ageable aluminum alloy, the wear strengths were investigated. Composites of aluminum alloys containing 2 to 10 wt of Al2O3 particles in the size range of 23.4 to 108 μm were prepared by adding alumina particles to a partially-solid vigorouslyagitated matrix alloy. For a given tribologic system, the sizes and ratios of optimum particles were determined from the point of the wear strengths of these materials, of which the wear strengths greatly increased according to the matrix materials. Alumina particles were subjected to preheating at 500°C for 8 hours. Particles were added into the alumina alloy heated up to semi-solid/ semi-liquid phase interval in an argon medium by using a mixer. Then furnace temperature was raised up to 800°C step by step. Later the composite materials were die cast and solidified and aged. The behavior of the composites was studied by using a pin-on-disk type machine. The largest wear strengths were obtained at an average particle size of 76.5 μm and percentage of 4% wt Al2O3. Increase in the wear strength of the composites was obtained as 3.85 times the wear strength of the matrix material.
Investigation on the elastic modulus and density of vacuum casted aluminum alloy 2024 containing lithium additions
(ASM International, 2000) Meric C.
The elastic modulus and density of (2024+LiX) alloys are investigated. To the alloy of 2024, the weight percentages of lithium added are 2, 3, and 4. Melting is carried out in an induction furnace under argon gas protection; casting is done under vacuum. To obtain the maximum strength and hardness, the specimens are solution heat treated under 495 °C and quenched in water at room temperature. Then, they are aged naturally and artificially. For the purposes of comparing, some of the specimens are melted under argon gas, but casting is done without vacuum. All the specimens are subjected to tension tests. As a result of this work, the alloys of aluminum that are difficult to manufacture by the known methods are manufactured safely by the vacuum casting method. For 1% of lithium added to the alloy, an increase of 6% in the elastic modulus and 3% decrease in the density are obtained. The specific elastic modulus, E/ρ, ratio increases by about 10% for each 1% addition of lithium.
Physical and mechanical properties of cast under vacuum aluminum alloy 2024 containing lithium additions
(Elsevier Science Ltd, 2000) Meriç C.
Physical and mechanical properties of aluminum alloy 2024 containing lithium additions were investigated. Lithim (2, 3, and 4 wt%) was added to the alloy of 2024. Melting was carried out in an induction furnace under argon gas protection; casting was performed under vacuum. The cast material was hot extruded to produce tension test rods. To obtain the maximum strength and hardness, the specimens were solution heat treated at 495 °C, then quenched in water at room temperature. They were then aged. For the purposes of comparison, some of the specimens were melted under argon gases, but casting was done without vacuum. All the specimens were subjected to tension and hardness tests. In this study, an increase of 6% in the modulus of elasticity and 3% decrease in the density were obtained for 1% lithium added to the alloy. The mechanical properties of the alloys cast under vacuum were found to be better than those cast without vacuum. Whatever the lithium percent in the alloys, all the mechanical properties reached their maximum level in 1 week of natural aging; for artificial aging, maximum levels were reached at 120 °C in 24 h, at 160 °C in 16 h, at 190 °C in 12 h, and 200 °C in 2 h. By increasing the lithium percent, the specific elastic modulus (E/ρ) of the alloy increased rapidly but the specific strength (σ/ρ) remained constant. Thus, aluminum lithium alloys that are difficult to manufacture by known methods can be manufactured safely by the vacuum metallurgy method.
The effect of precipitation-hardening conditions on wear behaviours at 2024 aluminium wrought alloy
(2003) Kaçar H.U.; Atik E.; Meriç C.
In this study, wear behaviours of 2024 aluminium wrought alloy were investigated in different tribological conditions based on its ageing conditions. For this purpose, the alloy aged in five different temperatures and periods (at room temperature for 1 week, at 120°C for 24h, at 150°C for 18h, at 160°C for 16h, at 200°C for 2h) was worn in pin-on disc model wear test apparatus using different abrasive grit size (5, 11, 18 and 30μm SiC papers). Furthermore, the effects of different sliding speeds (0.078, 0.156, 0.208 and 0.338ms-1) and loads (6.45, 9, 9.3 and 11N) on wear resistance were also examined. It was measured amounts of mass loss and examined worn surfaces. The mass loss of the specimens increased with load and the abrasive grit size. © 2003 Published by Elsevier B.V.
Determination of hardness of pre-aged AA 6063 aluminum alloy by means of artificial neural networks method
(Association for Scientific Research, 2004) Durmuş H.; Ünlü B.S.; Meriç C.
A lot of experiments must be conducted in order to find an appropriate technology for the calculation of strength of the materials, which wastes both man power and money. For this reason artificial neural networks (ANNs) have been used to search the optimum technology proper for pre-aged AA 6063 aluminum alloy. In this study, ANNs were used to compare experimental results and test data were used for teaching of the ANNs. This paper examines the changes in the hardness of AA 6063 alloys when heat treated at different pre-aging treatments. The alloy was solution treated for 1 hour at 525±3 °C and quenched in water. After quenching, samples were subjected to five different pre-aging times, 2 hours, 1 day, 3 days, 7 days. On the other hand, some specimens were not pre-aged. Artificial age temperatures were selected as 160 °C and 180 °C. The hardness values of these under-aged alloys were measured. When the pre-aging time was 7 days, the hardness values of the specimens increased. An excellent correlation was found between experimental hardness results and ANNs hardness results.
Mechanical properties and microstructural evaluation of AA5013 aluminum alloy treated in the semi-solid state by SIMA process
(2004) Saklakoglu N.; Saklakoglu I.E.; Tanoglu M.; Oztas O.; Cubukcuoglu O.
The microstructure and mechanical properties of AA5013 aluminum alloys prepared by strain-induced melt activation (SIMA) process were studied to investigate the effects of cold working and heat treatment conditions. The specimens subjected to deformation ratios of 30 and 50% and various heat treatment time and temperature regimes were characterized in the present study. The results revealed that for the desired microstructure of the alloy, the optimum heat treatment temperature and time were 650°C and 60min, respectively, for both deformation ratios. However, the specimens with 50% cold working exhibited more brittle behavior while they contain finer grains with uniform distribution along the cross-sections as compared to 30% cold working. © 2004 Elsevier B.V. All rights reserved.
Effect of aging on abrasive wear of deformable aluminum alloy AA6351
(2004) Meriç C.; Atik E.; Kaçar H.
Special features of abrasive wear of deformable aluminum alloy AA6351 are studied as a function of aging conditions and modes of friction tests. After aging in different modes the specimens are tested for wear in a special installation by the method of "brad against disk" with the use of abrasives with different grain sizes. The effects of different speeds of sliding and loads on the wear resistance and surface roughness are studied. © 2004 Plenum Publishing Corporation.
Determination of hardness of AA 2004 aluminium alloy under ageing conditions by means of artificial neural networks method
(2004) Atik E.; Meric C.; Karlik B.
As known, 2XXX and 7XXX Aluminium wrought alloys can have high strength values by means of precipitation hardening heat treatment. Determination of the precipitation hardening conditions, which can give the most suitable strength values of an alloy, requires numerous tests. But the results of this process which require long time and high cost can be obtained in a shorter time and at a lower cost with less data by means of Artificial Neural Networks method. Since this method is used, less number of experiments and therefore less data are needed. Then other values are found by means of Artificial Neural Networks (ANN) method. This paper, presents the feed forward ANN to determine hardness of alloy for different temperatures. For this purpose, a classic Back-Propagation Algorithm was used that is structure as 1:2:4.
Effects of various parameters on dynamic characteristics in adhesively bonded joints
(2004) Kaya A.; Tekelioǧlu M.S.; Findik F.
Adhesively bonded lap joints are used extensively in various industries. Some disadvantages like holes, thermal effects occurring in the bolted, welded, riveted, and soldered joints are not in question in adhesively bonded joints. Strong adhesive materials used in bonding have been greatly developed in recent years, and then the properties of lightness, sealing, corrosion resistance, heat and sound isolation, damping, and quickly mounting facility have been highly improved. In this work, effects of various dynamic characteristics in the adhesively bonded joints subjected to dynamic forces are investigated using the finite element method. The investigation is conducted on a three-dimensional model. The finite element model of the joint is obtained using isoparametric three-dimensional elements having eight nodes with three degrees of freedom each. Mesh generation is accomplished automatically in a computer. The joint is modeled as a thin plate clamped from the left side. The in-plane vibration analysis is constructed. First, the natural frequencies and mode shapes are obtained, and then point and transfer receptances are extracted, employing structural damping. It is observed that the damping greatly decreased the resonance amplitudes. © 2004 Elsevier B.V. All rights reserved.
The use of neural networks for the prediction of wear loss and surface roughness of AA 6351 aluminium alloy
(Elsevier Ltd, 2006) Durmuş H.K.; Özkaya E.; Meriç C.
Artificial neural networks (ANNs) are a new type of information processing system based on modeling the neural system of human brain. Effects of ageing conditions at various temperatures, load, sliding speed, abrasive grit diameter in 6351 aluminum alloy have been investigated by using artificial neural networks. The experimental results were trained in an ANNs program and the results were compared with experimental values. It is observed that the experimental results coincided with ANNs results. © 2004 Elsevier Ltd. All rights reserved.
Effect of aging on the abrasive wear properties of AlMgSi1 alloy
(Elsevier Ltd, 2006) Meriç C.; Atík E.; Kaçar H.
In this paper, the wear performance of the aged AlMgSi1 alloy was investigated. Great improvements in mechanical properties of Al alloys can be achieved by suitable solution treatment and aging operations. A pin-on-disk wear machine was designed and developed for abrasive wear tests. The wear resistance was evaluated using a pin-on-disk wear testing method with a SiC abrasive paper counterface. The variation of wear volume is presented as a function of applied normal load, abrasive grit size and sliding distance for running speed. Mass losses were measured within a load range of 6.45-11 N, a sliding velocity range of 0.078-0.338 m/s and abrasive grit size of 5-30 μm. The effects of different sliding speeds and loads on wear resistance and surface roughness were also examined. It was measured amounts of mass loss and examined worn surfaces. Metal microscope was used to study the microstructures of the wear scars. Natural aged specimen observed maximum wear resistance. © 2005 Elsevier Ltd. All rights reserved.
Microstructural evolution of ETIAL 160 aluminium alloy feedstock produced by cooling slope casting
(Trans Tech Publications Ltd, 2008) Saklakoglu N.; Birol Y.; Kasman Š.
Owing to its superior flow and mould-filling capability, a fully globular structure is essential for semisolid processing technologies. The present work was undertaken to identify the cooling slope casting process parameters that, upon heating to the semisolid state, gives the required globular structure for the ETIAL 160 alloy. Of the two pouring temperatures investigated, 605 °C and 615 °C, the lower pouring temperature was found to provide more globular grains surrounded by liquid phases.
Tribological and mechanical properties of Al alloyed bearings
(2009) Ünlü B.S.; Durmuş H.; Akgün S.
Aluminum based alloys are widely used as journal bearing materials in tribological applications. Duralumines, AlMgSi are widely used as journal bearing materials for aluminum based alloys. These alloys provide properties expected from journal bearings. In this study, tribological and mechanical properties of these journal bearings manufactured from aluminum alloys were investigated. SAE 1050 steel shaft was used as counter abrader. Experiments were carried out in every 30 min for the total of 150 min by using radial journal bearing wear test rig. Wear resistance of Al alloyed bearings increased about 2-3 times and journal wear resistance increased about 2-8 times. The highest bearing wear rate occurred in pure Al bearings while the lowest bearing wear rate occurred in AlMgSi bearing. © 2009 Elsevier B.V. All rights reserved.
Semisolid microstructure evolution during cooling slope casting under vibration of A380 aluminum alloy
(2010) Gencalp S.; Saklakoglu N.
This study is concerned with the influence of the vibration at a specific frequency to the inclined plate during cooling slope casting. A380 aluminum alloy was employed in the present work. The alloy was poured from the inclined plate with an angle of 60and a length of 500mm at a pouring temperature of 630C. The pouring was carried out on an inclined plate with and without vibration. Microstructures of specimens obtained from both conditions were examined. Grain size analysis of specimens was carried out. Experimental results showed that the application of vibration affected the microstructure. Hence, it was determined that the application of vibration increased the nucleation and led to more breaking of dendrite arms. In this study, the convection of melt by vibration played an important role on formation of non-dendritic primary Al-particles. Copyright © Taylor & Francis Group, LLC.
Pin-on-disc characterization of 2xxx and 6xxx aluminium alloys aged by precipitation age hardening
(2010) Meyveci A.; Karacan I.; Çaligülü U.; Durmuş H.
In this study, wear behaviors of aged aluminium AA 2024 and AA 6063 alloys were investigated. AA 2024 and AA 6063 aluminium alloys were solution treated at two different temperatures of 490 and 520 °C. Then all samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140 °C, 180 °C and 220 °C) for five different periods of time (2, 4, 6, 8, 10). The microstructures of the aged samples were examined by optical microscope, SEM-EDS and X-ray analysis. The hardness values of the aged samples were measured by microhardness tests. Wear tests were carried out on the pin-on-disc model wear test apparatus under sliding velocity at 2 m s-1 speed, 400, 800, 1200 and 1600 m sliding distances for 10, 20 and 30 N variable loads. The mass-loss values of the aged samples were tested by wear tests. As a result of this study, the hardness of the second phase precipitated samples was found to be higher than that of the as-cast samples and it increased with increasing the solution temperature and aging periods. The study also revealed that the wear rate and friction coefficient can be decreased with increasing the solution temperatures and aging periods. Crown Copyright © 2009.
A study of wear of aged aluminum alloys 2XXX and 6XXX within the manova statistical analysis
(2011) Meyveci A.; Karacan Í.; FIrat E.H.; ÇalIgülü U.; Durmuş H.
Statistically processed data on the microstructure and wear of aged aluminum alloys AA2024 and AA6063 are presented. Results of wear tests are analyzed using multidimensional analysis of variance (MANOVA) with 95% confidence interval for statistically significant deviations. It is shown that the temperature and the duration of the aging are statistically significant factors affecting wear of aluminum alloys 2XXX and 6XXX. © 2011 Springer Science+Business Media, Inc.
The effects of cooling slope casting and isothermal treatment on wear behavior of A380 Alloy
(2011) Saklakoglu N.; Gencalp S.; Kasman S.
In this study, A380 aluminum alloy feedstock produced with cooling slope casting was exposed to isothermal treatment to obtain a globular microstructure which is a key feature for semisolid forming. The dendritic primary phase in the conventionally cast A380 alloy has readily transformed into a non-dendritic one in ingots cast over a cooling plate from pouring temperatures between 615, 630 and 650 °C. After the casting process, isothermal treatment was carried out at 565 °C in induction unit. Isothermal treatment yields a globular microstructure. To determine the tribological properties of this alloy, a pin-on-disc tribometer was used to carry out tribological tests under dry sliding conditions. The results showed that both cooling slope casting and isothermal treatment has an effect on tribological properties. © (2011) Trans Tech Publications, Switzerland.
Formation of globular microstructure in A380 aluminum alloy by cooling slope casting
(2011) Saklakoglu N.; Gencalp S.; Kasman S.; Saklakoglu I.E.
Thixoforming and related semi-solid processing (SSP) methods require thixotropic materials. One of the many SSP techniques is the cooling slope (CS) casting process, which is simple and has minimal equipment requirements, and which is able to produce feedstock materials for semisolid processing. When the feedstock is reheated to the semisolid temperature range, nondendritic, spheroidal solid particles in a liquid matrix suitable for thixoforming are obtained. In this study, equipment for the CS technique was first established, and then the effects of the pouring temperature and inclined slope angle on the microstructures of A380 aluminum alloy (ISOAlSi8Cu3Fe) were studied. Optimum parameters for thixoforming experiments were selected, and it was found that the microstructure produced by the inclined plate depended on its angle and the pouring temperature. © (2011) Trans Tech Publications, Switzerland.
Investigation of the influence of the pre-aging process on the hardness of 6082 and 7075 aluminum alloys
(Carl Hanser Verlag, 2012) Şahin S.; Durmu H.; Yüksel N.; Manisa M.
In this study, the effect of pre-aging time and temperature on mechanical properties of aluminium alloys 6082 and 7075 has been investigated. Pre-aging has been applied at 50, 60, 70 and 80 °C for 24, 72, 144 hours after solution treatment process at 560 °C for 1 hour. Then these samples have been subjected to an aging process at 180 °C and 125 °C. The hardness of samples has been measured during aging process regularly. Eventually, it was determined that if pre-aging process is performed at low temperature, an increase of hardness occurs and hardness decreases with increasing temperature during aging. © Carl Hanser Verlag, München.
The effect of the retrogression process on the wear behaviour of a 7075 aluminium alloy
(Carl Hanser Verlag, 2012) Durmus H.; Uzun R.O.; Şahin S.; Yüksel N.
Retrogression and re-aging (RRA) process are applied in an attempt to enhance mechanical properties and corrosion resistance of 7075 aluminium alloys. In this study, retrogression and re-aging process have been applied to a 7075 aluminium alloy at 170 °C for 5, 40, 80 min and wear resistance of RRA applied samples have been investigated by ball-on-disc wear test apparatus. Sliding distance has been chosen as 300 meters. Re-aging procedure has been carried out at 125 °C for 10, 20 and 30 hours. Minimum wear loss has been obtained by retrogression for 40 min and aging for 30 hours. © Carl Hanser Veriag, München.

Browsing by Subject "Aluminum alloys"

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