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Öğe Characterization and Reduction Behavior of Cold-Bonded Composite Pellets for Direct Reduction Using an Organic Binder(Springer, 2013) Cevik, E.; Ahlatci, H.; Sun, Y.The purpose of this study was to investigate the reduction behavior of cold-bonded composite pellets produced from low-grade hematite iron ore using molasses solution at various concentrations, as well as their physical and chemical properties. Direct-Reduction Iron (DRI) technology makes it possible to assess low-grade iron ores and convert them into scrap at facilities that have electric arc furnaces. The reductant used was coke with fixed carbon of 86.04%. The alkalinity rate was adjusted to 0.7 by adding calcium carbonate. In the composite pellets produced, the 300 N/pellet compression strength recommended in the literature was achieved with a Fe-tot/C-fix ratio of 2.5 and 3 using a 50% concentrated molasses solution. Composite pellets prepared with a Fe-tot/C-fix ratio of 3.5 using a 40% concentrated molasses solution reached a compression strength of 496 N/pellet. The porosity is inversely proportional to the increase in compression strength and binder concentration. Reduction experiments were conducted by applying different temperatures and durations to samples possessing optimum conditions for each Fe-tot/C-fix ratio: the best result was achieved with a 88% reduction rate in composite pellets with a Fe-tot/C-fix ratio of 3.5 at the end of 1 h. Pig iron nuggets were characterized using an optical microscopy (LOM) and a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).Öğe Development of Aluminum Alloy AA5754 Production with a Different Magnesium Content by a Twin-Roll Casting Process(Springer, 2015) Turbalioglu, K.; Sun, Y.; Turen, Y.The effect of magnesium content and different thermomechanical treatment regimes on structure formation for sheet aluminum alloy AA5754 produced by twin-roll casting technology is evaluated. Cast sheets of alloy AA5754 containing 2.8, 3.0, and 3.2 wt.% magnesium 6 mm thick are cold rolled to a thickness of 1 mm. Three thermomechanical treatment regimes and annealing for alloy AA5754 are studied. Specimens obtained by this technology are strength tested. Grain size and distribution within the structure of finished sheet workpieces are determined by a standard procedure. With an increase in magnesium content in specimen grain diameter is considerably reduced. All specimens, prepared by a supplementary production scheme using homogenizing heat treatment in the final annealing stage, have maximum ductility, and also higher values of ultimate and yield strength than for specimens prepared using other production schemes and changed magnesium content.Öğe Dry sliding wear behaviour of Fe-0.4C-25Cr-XNi cast steels(Elsevier Science Sa, 2006) Sun, Y.; Ahlatci, H.; Ozdogru, E.; Cimenoglu, H.The effect of composition and heat treatment (solutionizing at 1200 degrees C and aging at 750 degrees C) on the room temperature mechanical properties (hardness and impact toughness) and dry sliding wear resistance of Fe-0.4C-25Cr-XNi steels (where nominal Ni contents were 4, 12 and 20 wt.%) have been investigated. The steel containing 4 wt.% Ni had ferritic and others (12 and 20 wt.% Ni) had austenitic matrixes along with M23C6 type chromium carbides. The applied heat treatment resulted in precipitation of sigma phase in austenitic matrix, which was accompanied by an improvement in hardness and a decrease in impact toughness. Ferritic matrix steel exhibited higher hardness and lower impact toughness than austenitic matrix steels. The results of the wear tests conducted on an unlubricated M2 quality tool steel disc revealed that at test pressures lower than 2.2 N/mm(2), the dominant wear mechanism was mild wear. However, at high test pressures (> 2.2 N/mm(2)) severe wear mechanism was operative. Increase of hardness and decrease of toughness resulted in a decrease in wear resistance under mild wear conditions. However, these mechanical properties were not effective on wear resistance under severe wear testing conditions. (c) 2005 Elsevier B.V. All rights reserved.Öğe Effect of copper addition on wear and corrosion behaviours of Mg2Si particle reinforced composites(Elsevier Sci Ltd, 2012) Palta, A.; Sun, Y.; Ahlatci, H.The purpose of this study is to investigate the effect adding Cu has on the wear and corrosion properties of in situ'' Mg2Si particle reinforced Al-12Si-20Mg matrix composites, produced with help of the nucleation and growth of the reinforcement from the source matrix, in order to overcome the disadvantages of composites produced by externally reinforcing ceramic particles. Composites known as Al-12Si-20Mg-XCu were produced by adding Cu, at the rate of 1%, 2%, and 4%, to the Al-12Si-20Mg alloy in order to achieve this purpose. The microstructural characterisation, hardness, wear and corrosion properties of composites, produced using the casting method, were analysed. Dry environment wear experiments for investigated alloys were conducted using a pin-on-disc type wear device under different loads and at different sliding distances. The change in weight loss of the solution containing 30 g/l NaCl + 10 ml/l HCl, and the tafel extrapolation method were used to analyse corrosion behaviour. Results of microstructural characterisation concluded that as the amount of Cu added to the Al-12Si-20Mg alloy increased, the size and volume of the Mg2Si particle, formed within the matrix, decreased, and CuAl2 intermetallics formed within the matrix. Results of wear experiments concluded that adding Cu developed wear resistance under small loads; however, reduced wear resistance under high loads. According to results of corrosion experiment, corrosion resistance increased with the addition of Cu. (C) 2011 Elsevier Ltd. All rights reserved.Öğe Effect of indium addition on microstructure and mechanical properties of AS-CAST and hot-rolled AM60 magnesium alloy(TANGER Ltd., 2017) Zengin, H.; Turen, Y.; Ahlatci, H.; Sun, Y.In this study, effect of indium (In) addition on microstructure and mechanical properties of AM60 magnesium alloys was investigated. In additions were made by 0.2, 0.5 and 1 wt.%. Alloys were produced by conventional gravity casting in a steel mould. A homogenization treatment at 350 °C for 24 h was performed after casting processes. Homogenized samples were 1 pass hot-rolled by 40 % thickness reduction at 350 °C. The results showed that the average grain size of as-cast and hot-rolled AM60 alloys decreased with In addition. SEM analysis revealed that In addition led to formation of tiny Mg-In binary second phases at triple junctions. Tensile strength of as-cast AM60 alloy increased with increasing amount of In up to 0.5 wt.% above which it decreased. However, after hot-rolling process, AM60 alloy containing 0.2 wt.% In showed the best tensile properties. These improvements were attributed to the refinement of microstructure and dispersion strengthening by Mg- In intermetallic phases. © 2017 TANGER Ltd., Ostrava.Öğe Effect of Lanthanum on the Microstructure and Mechanical Properties of Hot-Rolled Magnesium Alloy AZ31(Springer, 2019) Kara, I. H.; Ahlatci, H.; Turen, Y.; Sun, Y.The effect of lanthanum additions (0.2 - 1.0%) on the microstructure and mechanical properties of magnesium alloy AZ31 is studied after hot rolling with deformation of 15 and 30%. The microstructure is analyzed by the methods of x-ray diffractometry, optical microscopy and scanning electron microscopy. The mean values of the ultimate strength, elongation and contraction are determined in tensile tests.Öğe Effect of Magnesium Additions on Composites with Al and Al-12% Si Matrices Strengthened with B4C and Prepared by Infiltration Under Pressure(Springer, 2016) Cevik, E.; Sun, Y.; Ahlatci, H.; Turen, Y.Metallographic and x-ray phase analyses are used for metal-matrix composites Al - B4C and (Al - 12% Si) - B4C with a volume fraction of 60% boron carbide prepared by infiltrating a pressed workpiece with metal under pressure. It is shown that with introduction of 1 to 4% Mg into a metal matrix composite porosity is reduced from 7 to 1%.Öğe EFFECT OF PEAK-AGED HEAT TREATMENT ON CORROSION BEHAVIOR OF THE AA6063 ALLOY CONTAINING Al3Ti(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2012) Cevik, E.; Sun, Y.; Ahlatci, H.The purpose of this study is to analyse the microstructure and corrosion properties of homogenised and aged AA 6063 aluminium alloys, containing up to 2% Ti, after the conventional casting technique. The microstructure of the homogenised and aged alloys was examined using an optic microscope, and scanning electron microscope. The micro-hardness test was used for the hardness measurements of the investigated alloys. Corrosion tests were performed by suspending samples of certain sizes into 30 gr/l NaCl + 10 ml/l HCl solutions, measuring the mass loss; potentiodynamic polarisation measurements were carried out in the same solution. The microstructure characterization of the investigated alloys shows the Al (matrix), non-shaped dark globular grey-coloured phase and rod-shaped phases formed at the grain boundaries. The non-shaped dark grey-coloured phase is Mg2Si. The rod-shaped phase, formed in the microstructure of the Ti-added AA 6063 alloys, is Al3Ti. The Ti content of the alloy increases, the Al3Ti phase tends to elongate and become plated. The results of the corrosion tests proved that the corrosion rate decreased in alloys containing less than 1% Ti, and the rate of corrosion increased in alloys containing more than 1% Ti, regardless of whether the alloys were homogenised and aged. Another observation was that aging heat treatment improved corrosion resistance.Öğe Effect of sn addition on corrosion properties of As-Cast and Hot-Rolled AZ31 magnesium alloys(Trans Tech Publications Ltd, 2017) Turen, Y.; Guzel, D.; Zengin, H.; Sun, Y.; Ahlatci, H.In this study, the effect of Sn addition on corrosion resistance of as-cast and hot rolled AZ31 magnesium alloy was investigated. Sn additions were made by 0.2 wt%, 0.5 wt% and 1 wt%. An electric resistance furnace was used to produce alloys. Hot rolling process was performed at 350 °C by 40% thickness reduction at one rolling pass. Microstructure characterizations were performed by optical (OM) and scanning electron microscope (SEM). Immersion tests and electrochemical analyses were performed to investigate the corrosion resistance of the alloys. A 3.5% NaCl working solution at room temperature was used in both corrosion tests. The results showed that Sn addition decreased the primary dentrite size and restricted the growth of secondary dentritic arm. The as-cast structures transformed to dynamically recrystallized grain structures after hot-rolling process in all the alloys. Corrosion resistance of AZ31 magnesium alloy tended to decrease with Sn addition. This decrease was more clear in homogenized and hot-rolled states while there were some flactuations in as-cast states. © 2017 Trans Tech Publications, Switzerland.Öğe Effect of Ti addition on corrosion properties of As-Cast and Hot-rolled AM60 magnesium alloys(Trans Tech Publications Ltd, 2017) Sun, Y.; Aydin, N.U.; Turen, Y.; Ahlatci, H.; Zengin, H.This study investigates the effect of Ti addition (0.2, 0.5, 1wt%) on corrosion resistance of as-cast and hot rolled AM60 magnesium alloy. The results showed that Ti addition resulted in an alteration of the microstructure of as-cast AM60 magnesium alloy by decreasing the amount of-Mg17Al12 eutectic phase. Homogenization treatment resulted in the dissolution of the most of the-Mg17Al12 phases. Corrosion behaviors were investigated by immersion tests and electrochemical analysis. Homogenized samples exhibited the lowest corrosion rate in immersion test while the best corrosion resistance was found for hot-rolled samples in electrochemical test. In hot-rolled state, Ti addition led to a slight change in the corrosion behaviour of AM60 magnesium alloy. © 2017 Trans Tech Publications, Switzerland.Öğe Effects of bismuth (bi) additions on microstructure and mechanical properties of AZ91 alloy(TANGER Ltd., 2015) Elen, L.; Zengin, H.; Turen, Y.; Turan, M.E.; Sun, Y.; Ahlatci, H.In this study, the effects of bismuth additions of 0.2, 0.5 and 1 wt% on microstructure and mechanical properties of AZ91 alloy were examined. A permanent mold casting procedure was carried out to produce the alloy billets under a mixed gas atmosphere of SF6 and CO2. Microstructural investigations showed that Mg3Bi2 intermetallic phases were formed in all the samples and it coarsened with increasing amount of Bi in AZ91 alloy. Furthermore, a finer dispersion of Mg17Al12 intermetallic phases was observed in the structures as the amount of Bi in AZ91 increased. It was also showed that increasing Bi addition increased the hardness of AZ91 alloy. However, the highest hardness value was found for the alloy having 0.5wt% Bi addition that means high amount of Bi can decrease the hardness of AZ91 alloy. On the other, there were no considerable changes in the tensile strengths and yield strengths of the alloys as the amount of Bi increased although a slight increase in both strengths were observed with increasing amount of Bi. Percent elongation at break showed a decrease as Bi addition increased.Öğe EVALUATION OF PRODUCT SINTER QUALITY IN BLENDS PREPARED WITH DOMESTIC AND IMPORTED FINE ORES AT KARDEMIR(Baski, 2022) Timur, T.; Cantürk, C.; Esin, F.; Acur, O.; Sevim, M.; Sun, Y.In Integrated Iron and Steel Plants, fine ores of a size that cannot be charged directly to the blast furnaces are combined by subjecting to surface melting under the melting temperature. As a result of sintering, it becomes usable in blast furnaces. Sinter is the most economical ferrous material input of blast furnaces. Blast furnaces production speed, efficiency, quality and economy of the product obtained depend on the raw materials used. In this study, the quality of the product sinter obtained by blending domestic and imported fine ores in different proportions was evaluated. Physical (sieve analysis) and chemical (XRF) properties of the blend were determined by taking samples from the blend area to represent each blend. Blends has been categorized and sintered as domestic and imported fine ore, calibrated ore, pellet dust and other (waste dusts of some plant). Physical (sieve analysis, drum test), chemical (XRF) and metallurgical analysis (RUL, RDI) of the obtained sinters were made. When all analysis results were examined, it was concluded that the most suitable mixture for sinter used in blast furnaces would be provided using at least 30% imported ore. © IMCET 2022. All rights reserved.Öğe Functionally Graded Material Production and Characterization using the Vertical Separator Molding Technique and the Powder Metallurgy Method(Dr D. Pylarinos, 2022) Kayabasi, I.; Sur, G.; Gokkaya, H.; Sun, Y.Functionally Graded Materials (FGMs) are advanced customized engineering materials that gradually and continuously change their composition. The current study investigated the production feasibility and some post-production mechanical/physical properties of B4 C particle-reinforced (avg. 40µm) AA7075 matrix (avg. 60µm) FGM composites with the vertical separator molding technique using the high-temperature isostatic pressing powder metallurgy method. FGMs produced consist of three (0 – 30 – 60 wt. % B4 C) and four (0 – 20 – 40 – 60 wt. % B4 C) layers. The powders were mixed in a power blender mixer for 2h and were placed in the mold sections with a vertical separator. The lid was closed, and a pre-pressure of 10Mpa was applied. The FGM green sheet was transferred from the vertical separator mold to the hot work tool steel with a press. In this mold, FGMs were sintered at 560°C for 30 min under a pressure of 325MPa. Microstructural examinations did not reveal any separation or crack formation in the layer transition regions of the FGMs. In addition, a relatively homogeneous B4 C reinforcing distribution was observed in the layers with a low reinforcement ratio (wt. 20% and 30%) compared to the other layers. The highest hardness was 170 HBN in one layer of the four-layer FGM containing 40% by weight B4 C reinforcement. The highest transverse rupture strength was measured in the test performed from the region with the most reinforcement of the four-layer FGM at 482MPa. © 2022, Dr D. Pylarinos. All rights reserved.Öğe Functionally Graded Material Production and Characterization using the Vertical Separator Molding Technique and the Powder Metallurgy Method(Eos Assoc, 2022) Kayabasi, I.; Sur, G.; Gokkaya, H.; Sun, Y.Functionally Graded Materials (FGMs) are advanced customized engineering materials that gradually and continuously change their composition. The current study investigated the production feasibility and some post-production mechanical/physical properties of B4C particle-reinforced (avg. 40 mu m) AA7075 matrix (avg. 60 mu m) FGM composites with the vertical separator molding technique using the high-temperature isostatic pressing powder metallurgy method. FGMs produced consist of three (0 - 30 - 60 wt. % B4C) and four (0 - 20 - 40 - 60 wt. % B4C) layers. The powders were mixed in a power blender mixer for 2h and were placed in the mold sections with a vertical separator. The lid was closed, and a pre-pressure of 10Mpa was applied. The FGM green sheet was transferred from the vertical separator mold to the hot work tool steel with a press. In this mold, FGMs were sintered at 560 degrees C for 30 min under a pressure of 325MPa. Microstructural examinations did not reveal any separation or crack formation in the layer transition regions of the FGMs. In addition, a relatively homogeneous B4C reinforcing distribution was observed in the layers with a low reinforcement ratio (wt. 20% and 30%) compared to the other layers. The highest hardness was 170 HBN in one layer of the four-layer FGM containing 40% by weight B4C reinforcement. The highest transverse rupture strength was measured in the test performed from the region with the most reinforcement of the four-layer FGM at 482MPa.Öğe The improvement of the mechanical properties of AA 6063 aluminum alloys produced by changing the continuous casting parameters(2011) Turbalioglu, K.; Sun, Y.This study aims to improve manufacturing parameters of the AA 6063 aluminum alloy produced with the vertical continuous casting method. For this purpose, the billets were manufactured at different metal temperatures and different casting speeds, using the vertical continuous casting method. Billet specimens were prepared at two different conditions: casting and homogenization heat treatment. The homogenization heat treatment was applied at 580°C for 4 h. Specimens at each group were exposed to microstructure analyses and hardness and tensile tests in order to determine their mechanical properties. As a result of the applied experiments, it was determined that the mechanical properties varied depending on metal temperature and casting speed; and the optimum casting parameters were 690°C metal temperature and 100 to 110 mm/min casting speed. ©2011 Academic Journals.Öğe Investigation of microstructure, mechanical and wear behaviour of B4C particulate reinforced AZ91 matrix composites by powder metallurgy(National Institute of Science Communication and Information Resources (NISCAIR), 2019) Aydin, F.; Sun, Y.; Emre, Turan, M.In this study, AZ91 and AZ91 matrix composites reinforced with three weight fractions (10, 20 and 30 wt. %) of B4C particulates have been produced by powder metallurgy using hot pressing. Microstructure, hardness, density and mechanical properties of the samples are investigated. Microstructure characterization revealed the uniform distribution of particulatesin matrix. The presence of Mg, Mg17Al12 and B4C are verified by SEM and XRD. Wear tests are performed under loads of 5, 10, 20 and 30 N. Wear tests show that wear performance of the composites is improved with increasing particulate content. Observed wear mechanisms are oxidative and abrasive. The addition of B4C particulates led to significant increase in hardness, 0.2% compressive yield strength, ultimate compressive strength and failure strain. © 2019, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.Öğe MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF B4C REINFORCED AlSi12-XMg MATRIX COMPOSITES(Scibulcom Ltd, 2015) Cevik, E.; Sun, Y.In this study, mechanical and tribological behaviours of composites produced by using pressure infiltration method were investigated. Preforms were prepared by using B4C particles with an average grain size of 45 mu m and a volume rate of 60%. Four different matrixes produced by adding different proportions (0, 1, 2 and 4 wt.%) of Mg to AlSi12 aluminium alloy were melted at 800 degrees C and infiltrated to the preform with a pressure of 8 bars. Results whose microstructure characterisation was conducted by using light optical (LOM) and scanning electron (SEM) microscope were supported with X-ray diffraction (XRD) analyses. With the increasing addition of Mg, hardness values and compressive strength increased. This improvement in mechanical properties improved the wear resistance. While the lowest weight loss was achieved with the addition of 4% Mg in low loads as a result of wear tests, the best wear resistance in high loads was observed in composites produced with the addition of 1% Mg.Öğe Mechanical and tribological behaviour of B4C reinforced AlSi12-XMg matrix composites(Scibulcom Ltd., 2015) Cevik, E.; Sun, Y.In this study, mechanical and tribological behaviours of composites produced by using pressure infiltration method were investigated. Preforms were prepared by using B4C particles with an average grain size of 45 mm and a volume rate of 60%. Four different matrixes produced by adding different proportions (0, 1, 2 and 4 wt.%) of Mg to AlSi12 aluminium alloy were melted at 800°C and infiltrated to the preform with a pressure of 8 bars. Results whose microstructure characterisation was conducted by using light optical (LOM) and scanning electron (SEM) microscope were supported with X-ray diffraction (XRD) analyses. With the increasing addition of Mg, hardness values and compressive strength increased. This improvement in mechanical properties improved the wear resistance. While the lowest weight loss was achieved with the addition of 4% Mg in low loads as a result of wear tests, the best wear resistance in high loads was observed in composites produced with the addition of 1% Mg.Öğe Microstructure and corrosion properties of homogenized AZ31 and AZ31+1%La magnesium alloys(Trans Tech Publications Ltd, 2017) Ahlatci, H.; Kara, I.H.; Turen, Y.; Sun, Y.; Zengin, H.Energy efficiency and decreasing emission of greenhouse gasses emerge that the importance of Mg alloys. Mg alloys can begin to supersede the steel and aluminum for structural applications, thanks to the developing of mechanical properties or corrosion resistance of these alloys. Rare earth metals such as Gd, Ce, Y and Nd have been utilized at AZ31 Mg alloys for this purpose in recent years. In this study, the effects of La addition and homogenization heat treatment on microstructure, hardness properties and corrosion resistance of AZ31 and modified AZ31 Mg alloys produced by low pressure die casting method were investigated. © 2017 Trans Tech Publications, Switzerland.Öğe Microstructure and corrosion properties of homogenized Mg-4Zn-1La magnesium alloy(Trans Tech Publications Ltd, 2017) Zengin, H.; Turen, Y.; Ahlatci, H.; Sun, Y.; Kara, I.H.In this study, microstructure and corrosion behaviour of homogenized Mg-4Zn-1La magnesium alloy was investigated. Mg-4Zn-1La alloy was produced by low-pressure die casting method. Homogenization treatments were performed at 350 °C and 400 °C for 12, 18, 24 and 48 hours, followed by rapid cooling in water at room temperature. Microstructure characterizations showed that La addition led to a formation of semi-continuous network structure and islands of second phases which identified as T-phase (Mg7Zn3RE). A significant amount of second phase dissolution and an increase in-Mg grain size with increasing both homogenization time and temperature was observed. Homogenization treatment led to an improvement in corrosion resistance of Mg-4Zn-1La alloy. Homogenization at 400 °C resulted in better corrosion resistance than homogenization at 350 °C for all homogenization duration. © 2017 Trans Tech Publications, Switzerland.
