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Öğe Analysis of spur gear forms with tapered tooth profile(Elsevier Sci Ltd, 2008) Can, Yimaz; Misirli, CenkThis paper presents an analysis of the lateral extrusion of spur gear forms and a comparative evaluation of the methods of lateral extrusion and closed die forging of spur gear forms in terms of mechanical properties of the product. An upper bound solution for lateral extrusion of spur gear forms with tapered tooth profile has been developed. A kinematically admissible velocity field has been proposed. From the proposed velocity field the upper bound solution on relative punch pressure and extrusion load are determined with respect to chosen process parameters. The obtained results are compared with experimental results in order to illustrate the validity of the proposed velocity fields. This indicates that the analysis presented here renders better upper bound solution before corner filling occurs. In addition, gear forms of the same dimension have been produced by both lateral extrusion and closed die forging. The fatigue and hardness tests were applied to gear teeth produced by both processes. The fatigue tests were applied in a manner of three point bending tests. The effect of forming method on the fatigue behavior at the roots of gear teeth and hardness distribution along the radial direction of the tooth are investigated. (c) 2007 Elsevier Ltd. All rights reserved.Öğe Characteristic properties of AlTiN and TiN coated HSS materials(Emerald Group Publishing Ltd, 2015) Sahin, Mumin; Misirli, Cenk; Ozkan, DervisPurpose - The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail. Design/methodology/approach - In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500 degrees C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components. Findings - It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-coated HSS parts have the most valuable fatigue results. However, surface roughness of fatigue samples may cause notch effect. For this reason, surface roughness of coated HSS parts is compared with that of uncoated ones. While the average surface roughness (Ra) of the uncoated samples was in the range of 0.40 mu m, that of the AlTiN- and TiN-coated samples was in the range of 0.60 and 0.80 mu m respectively. Research limitations/implications - It would be interesting to search different coatings for cutting tools. It could be the good idea for future work to concentrate on wear properties of tool materials. Practical implications - The detailed mechanical and metallurgical results can be used to assess the AlTiN and TiN coating applications in HSS materials. Originality/value - This paper provides information on mechanical and metallurgical behaviour of AlTiN- and TiN-coated HSS materials and offers practical help for researchers and scientists working in the coating area.Öğe Characterization of Properties in Friction Welded Stainless Steel and Copper Materials(Springer, 2013) Sahin, Mumin; Cil, Ender; Misirli, CenkThe aim of this study is to investigate the metallurgical and mechanical properties of friction welded stainless steel-copper joints. One of the manufacturing methods used to produce parts made from different materials is the friction welding method. Application of classical welding techniques to such materials is difficult because of they have different thermal properties. Stainless steel-copper joints are inevitable for certain applications due to unique performances such as higher electric conductivity, heat conductivity, corrosion resistance, and mechanical properties. In the present study, austenitic stainless steel and copper parts were joined by friction welding. Tensile, fatigue, and notch-impact tests were applied to friction welded specimens, and the results were compared with those for the original materials. Microstructure, energy dispersive x-ray, and x-ray diffraction (XRD) analysis and hardness variations were conducted on the joints. Results showed that various intermetallic phases such as FeCu4 and Cu2NiZn occurred at the interface. It was found from the microstructure and XRD analysis that intermetallic phases formed in the interface which further caused a decrease in the strength of the joints. However, hardness of the copper increased slightly, whereas the hardness of steel decreases slightly on the horizontal distance from the center.Öğe A COMPARATIVE STUDY FOR OPEN DIE FORGING-EXTRUSION PROCESS OF CLOVER-SHAPED AND RECTANGULAR-SHAPED ALUMINUM ALLOY(Univ Tech Gheorghe Asachi Iasi, 2010) Misirli, Cenk; Can, YilmazThis paper overviews the metal forming process which is called forging-extrusion process. The aim of this process is manufactured of near net shape of many produce. In this study, two different shaped upper dies were used. A199.7 aluminum alloy was used for experiments. Aluminum billets which having same initial heights have been extruded with the same strokes. The forging loads were measured different deformation rate. Some of aluminum billets were lubricated and formed. Lubricated specimens were compared with the other specimens. The effect of metal forming process on the hardness distribution along the radial direction was investigated both of different geometries and lubricated conditions. In addition, the microstructures were investigated for clover shaped samples and rectangular shaped samples using transmission electron microscopy (TEM). It was found that both clover shaped samples and rectangular shaped samples have similar mechanical properties. The corresponding microstructure consisted of a mixture of elongated subgrains with dimensions similar to those observed in the initial billet. It is suggested that there is no considerable differences between two different geometries in terms of microstructure and lubrication.Öğe Determination of the Change in Electrical Conductivity of Single, Bimetallic and Trimetallic Cylindrical Billets with Plastic Deformation Induced by Upsetting Process(Univ Osijek, Tech Fac, 2022) Cetintav, Isik; Misirli, Cenk; Can, YilmazIn this study, measurement of the effect of singular, bimetallic and multimetallic materials exposed to cold plastic deformation on electrical conductivity properties was investigated. The main subject of this research is plastic deformation occurring in the upsetting process and changing the conductivity properties of the parts. In the experiments, steel, aluminium, copper, brass, bimetallic and multimetallic materials designed with different combinations of these materials were used as test materials. Experimental upsetting tests were performed as a height reduction ratio 10%, 20% and 30%. The electrical conductivity measurement results of the deformed samples were obtained with a conductivity measuring device. The results obtained from the experiments are presented in graphs with electrical conductivity axis that change due to deformation. As a result of the experiments and measurements, it was concluded that the electrical conductivity of the deformed materials generally decreased slightly due to the plastic deformation of the deformed materials, and the bimetallic and multimetallic materials were similar to the properties of the majority material.Öğe Effect of high temperatures on dry sliding friction and wear behaviour of CuCrZr copper alloy(Walter De Gruyter Gmbh, 2023) Misirli, Cenk; Ceviz, Mehmet; Cetintav, Isik; Kilic, HalilDry friction and wear behavior at high temperatures was investigated against an Al2O3 ball in order to characterize the wear rate, coefficient of friction (COF), hardness and thermal friction behavior at different temperatures in the wear-treated zones of the CuCrZr copper alloy. Experiments were fulfilled using a pin-on-disk wear device with the aid of a temperature modulated wear device at room temperature, 100, 200 and 300 ?. The loads applied during wear are given as 3N, 5N and 7N, respectively. In order to examine the morphological structure of the worn surfaces, appropriate samples were prepared and SEM (scanning electron microscopy) device was used. Similarly, EDS (energy dispersive x-ray spectrometry) was applied to worn surfaces to examine the abrasive-material interaction. Against the hardness of the material at 25 ?, the hardness value in measurements at 300 ? showed a small increase. The COF value increased at 100 ? and then decreased, while the wear rate increased significantly as the temperature increased. The temperature increase starting from RT up to 300 ? weakened the internal structure of the CuCrZr alloy and caused an increase in the wear rate. XRD test was used to show the phases that may occur in CuCrZr alloy due to temperature and heat treatment.Öğe The Effect of Temperature on Wear Performance of High-Velocity Oxy-Fuel Sprayed WC-10Co-4Cr Coating on AA7075-T6 Substrate(Springer, 2022) Ceviz, Mehmet; Misirli, Cenk; Karabeyoglu, Sencer SureyyaIn this study, the friction wear performance of a High-velocity oxy-fuel (HVOF) sprayed WC-10Co-4Cr coated AA7075-T6 substrate was investigated against a WC-4Co ball at different temperatures using a pin-on-disk tribometer. WC-10Co-4Cr coating was deposited with a commercial HVOF-K2 spray (GTV MF-HVOF-K 1000 compact), O-2 and kerosene as fuel gases with flow rates of 900 L/min and 26 L/h, respectively. Spraying was carried out with a rotation speed of 200 rpm, a particle feed rate of 1.8 rpm at a distance of 380 mm and a scanning distance of 5 mm. As HVOF spray, a commercial WC-10Co-4Cr powder (GTV 80.76.1.G) with a particle density of 4.63 g/cm(3) was utilized. The diffusion of coating to the substrate was investigated by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX). The hardness of the as-sprayed coating was measured using a micro Vickers hardness tester. The friction and wear tests were performed at a sliding speed of 100 mm/s for 1800 s under a fixed load of 3 N at 25, 100, 200 and 300 degrees C. The wear rate increased five times at 300 degrees C testing compared to room temperature (RT), but the average coefficient of friction (COF) value increased from 0.30 to 0.48 for 200 degrees C testing and then decreased to 0.36 for 300 degrees C. The powder and coating microstructures were analyzed using x-ray diffractometer (XRD) analysis. Morphological characterizations were accomplished by SEM and a wide field confocal microscope (WCM/profilometer), and wear mechanisms were examined. The wear mechanism was abrasive until 100 degrees C, but a temperature increase allowed for adhesive wear, plastic deformation and oxidation fatigue. Oxide layers and crack propagation took place in accordance with applied load and thermal expansion of the AA7075-T6 substrate. Oxide layers on the worn surface enabled the coefficient of friction to decrease after 200 degrees C. Oxide delamination and pile-ups were observed at 300 degrees C.Öğe Investigation of the friction behavior of plasma spray Mo/NiCrBSi coated brake discs(Walter De Gruyter Gmbh, 2021) Kilic, Halil; Misirli, Cenk; Mutlu, IbrahimThis paper presents the findings of comparative research conducted to find out the braking performance of a Mo/NiCrBSi coated automobile brake disc. The friction and wear behavior of the Mo/NiCrBSi coating (CD) used for the disc material was evaluated using a laboratory scale disc-pad dynamometer and compared with a reference disc (RD). The coating was deposited by means of the atmospheric plasma spray process on a grey cast iron substrate. Braking tests were performed according to the SAE-J2430 test standard. Disc microstructures were characterized by SEM and XRD. It was found that the bonding strength was good with an infinite rating between the accumulated coating layer and the substrate. The results show that the coated brake disc has a comparable coefficient of friction and that the amount of wear is lower than that of the reference disc. The addition of ductile phases to the disc coating was beneficial in reducing the coefficient of friction to an acceptable degree and also effectively improving wear resistance.Öğe AN INVESTIGATION OF UPSETTING OF BIMETALLIC METALS(Modtech Publishing House, 2011) Misirli, Cenk; Can, YilmazUpsetting is simplest but primary metal forming operation. Upsetting of single materials such as aluminum, steel, copper and porous materials has been investigated many researchers in terms of friction, barreling effect and contact pressure distributions due to its relevance in metal forming. Also different shapes such as elliptical and polygonal shapes have been studied. In this paper, upsetting of composite or in other words bimetallic metals were studied experimentally. Cylindrical specimens consisting of two different materials were used in the experiments. Specimens were prepared as aluminum sleeve and copper core and upset at different reduction. This metal combination present a material model of which chemical composition is different.Öğe An Investigation on Thermal Dry Sliding Wear Performance of Wrought AA 7075-T6(Springer India, 2022) Ceviz, Mehmet; Misirli, Cenk; Karabeyoglu, Sencer SureyyaThe thermal frictional behavior of AA 7075-T6 against a WC-6Co ball for different temperatures was investigated to characterize the worn surface in terms of wear rate, coefficient of friction (COF) and hardness using a high temperature pin-on-disk tribometer. Microstructural composition was depicted after etching to show the precipitates. The hardness of the sample tested at room temperature (RT) was measured as HV 158.0, which dropped by similar to 56% in the 300 degrees C test. The wear rate and COF values increased over 10X in accordance with test temperature. The temperature increase loosened the structure, and the wear rate was negatively affected. A detailed tribological characterization was carried out using SEM and EDX, and wear track profiles were observed by cutting the samples with EDM and then comparing with the cross-sectional profile images (WCM). At RT and 100 degrees C, a partial abrasive wear mechanism was present; however, the temperature increase improved plastic deformation and adhesive wear. Oxide layer formation allowed oxidation cracks, and temperature increase proportionally improved wear rate. Possible phases were investigated using XRD to show the heat treatment effect of test temperatures.Öğe Mechanical and metallurgical properties of AlTiN-coated HSS materials(Emerald Group Publishing Limited, 2013) Sahin, Mumin; Dinc, Murat; Misirli, CenkPurpose - The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN coating HSS materials in detail. Design/methodology/approach - In this study, high-speed steel (HSS) parts were processed by the way of machining and were coated with AlTiN on physical vapour deposition (PVD) workbench at approximately 650 degrees C for 4 h. Tensile strength, fatigue strength and hardness tests for AlTiN coated HSS samples were performed. Samples were also analyzed by energy dispersive X-ray analysis (EDS), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results were compared with uncoated HSS components. Findings - It was found that an amorphous aluminium-oxide layer emerges on surface of parts by AlTiN coating. This layer prevents further oxide formations. The coating thickness of AlTiN-coated sample is between 1,530 and 1,558 mu m. Compared to uncoated HSS, AlTiN coated HSS gives higher performance. Research limitations/implications It would be interesting to search different coatings for cutting tools. It could be the good idea for future work concentrated wear properties on tool materials using different coatings. Originality/value - This paper provides information on mechanical and metallurgical behaviour of AlTiN coated HSS materials and offers practical help for the researchers and scientists working in the coating area.Öğe Mechanical and tribological properties of a WC-based HVOF spray coated brake disc(Walter De Gruyter Gmbh, 2022) Kilic, Halil; Misirli, Cenk; Mutlu, Ibrahim; Timur, MustafaThermally sprayed WC-based coating systems are generally used to increase engineering components' wear resistance. This research presents the results of a comparative study conducted to examine the tribological characteristics of a new brake disc created with thermal sprayed WC-10Co4Cr coating. This study implemented braking tests on the WC-10Co4Cr coated brake disc against commercial friction material on a laboratory scale disc-pad tester and compared the findings with the reference disc. The coating system was created with a high velocity oxygen-fuel spraying on a cast iron disc. The braking tests followed the sections of the SAE-J2430 test procedure. The microstructure, phase composition and properties of the coating were characterized by SEM/EDS, XRD and Vickers microstructure. The effect of carbide coating on the friction and wear behaviour of the tribological system was examined. The WC-10Co4Cr coating has increased the hardness by 3 times with a thickness of 300 mu m compared to the cast iron surface. The amount of wear in the coated disc (CD) was reduced by about 85% compared to the reference disc (BD). The coefficient of frictions of BD and CD was found to be in the range of 0.43-0.61 and 0.47-0.62, respectively. The inclusion of hard phases (WC and W2C) in the disc coating played an important role in improving the sliding wear resistance by maintaining the coefficient of friction of the brake disc at an acceptable level. In brief, carbide coating could be claimed to be promising for challenging braking implementations.Öğe On materials flow using different lubricants in upsetting process(Emerald Group Publishing Limited, 2014) Misirli, CenkPurpose - The purpose of this paper is to apply the upsetting process to cylindrical specimens using flat end dies in which three types of lubricants were used. In many industrial processes, friction and lubrication have major advantages and are key during the metal forming process. Upset forging is a process which increases the diameter of the work-piece by compressing its length. Design/methodology/approach - The materials flow for various materials using different lubricants in upsetting was investigated in this study. AISI 304 austenitic-stainless steel and commercially pure aluminium (Al99.7) were used as the test materials. The upsetting process was applied to the cylindrical specimens using flat end dies. Three types of lubricants, namely, grease, graphite and SAE 40 oil, were used in this study. Experiments were performed using a hydraulic press, which has 5 mm/s ram speed, with a capacity of 150 metric tons. On the other hand, finite element methods (FEMs) have been carried out to analyse the forming performance for displacement prediction in the barrelling process. Findings - The results showed that the measured radius of the curvature of the barrel seemed to confirm the calculation values used before the initiation of the experimental process. It has been observed that the surface roughness had no considerable effect on the barrelling contour changes on the free surfaces, as it showed an increasing deformation ratio for all materials and lubricant types. However, minimum friction at the interface seems to occur with the grease lubricant. The present analyses show that FEMs, which can be used in the rapid prediction of required barrelling process displacements, are more suitable for use in a pressure distribution analysis for the development of the barrelling radius. Research limitations/implications - It would be interesting to search the material flow for more different materials and lubricants. It could be a good idea if future work could be concentrated on the material flow on upsetting by using different lubricants. Practical implications - Open-die forging, which is also known as the upsetting process, is one of the simplest forging operations used in bulk deformation processes. This operation can be explained as a solid work-piece which is positioned between two flat dies, and then with the aid of compression, the height of the work-piece is reduced under controlled working parameters during the upsetting process, in which friction and surface roughness are the major parameters playing an important role on the material flow. In a cold upsetting process, one of the undesirable conditions is that barrelling occurs as a consequence of friction between the work-piece and the die surfaces. The existence of this frictional constraint directly affects the plastic deformation of the work-piece, as friction causes barrelling in upsetting processes. However, it has been observed that the use of lubricants reduces the degree of bulging. Social implications - This paper will be useful for industrial applications. Originality/value - The main value of this paper is to contribute and fulfil in detail the material flow of various materials using different lubricants that are being studied so far in the literature.Öğe On properties at interfaces of friction welded near-nanostructured Al 5083 alloys(Springer London Ltd, 2012) Sahin, Mumin; Balasubramanian, N.; Misirli, Cenk; Akata, H. Erol; Can, Yilmaz; Ozel, KaanEqual-channel angular pressing is a material processing method that allows very high strains to be imposed, which leads to extreme work hardening and micro-structural refinement, with minimal change of external sample dimensions. It offers possibilities of good mechanical properties, such as high strength and ductility, while allowing flexibility of choice of alloy composition for better corrosion behavior, lower materials costs, and so on. This study characterizes for the first time the microstructure and properties of aluminum friction welded after severe plastic deformation via the equal-channel angular pressing method. In this study, 5,083 aluminum alloys, which were exposed to severe plastic deformation using square cross-sectional equal-channel angular pressing die, were joined with friction welding method. It was found that tensile and fatigue strengths of severe plastic deformed and welded specimens were higher than those of the purchased specimens. Hardness values were also consistent with the strength results. However, the refining of grain size as shown from microstructures results in a significant increase in hardness and mechanical properties.Öğe OPTIMIZATION OF THE PROCESS PARAMETERS OF FRICTION-WELDED St-Al JOINTS(Inst Za Kovinske Materiale I In Tehnologie, 2019) Sahin, Mumin; Misirli, Cenk; Selvi, SelcukFriction welding is a solid-state welding process. applicable to similar and dissimilar ferrous and non-ferrous metals. Combining aluminium and steel parts is one of the most suitable methods for obtaining cheaper and lightweight products. Due to their different properties, compositions of these materials provide multiple advantages. In the present study, stainless-steel and aluminium (St-Al) parts were friction welded with an aim to optimize the process parameters. The joints obtained with various process-parameter combinations were subjected to tensile tests. Empirical relationships were developed to predict the strength of the joints using the RSM (the response surface methodology) and the coherency of the model was tested. The tensile properties. microhardness variations, scanning-electron-microscopy (SEM) examinations, energy-dispersive-spectroscopy (EDS) and X-ray diffraction (XRD) analyses of the welded specimens were evaluated. Additionally, the tensile-strength test results were analyzed using analysis of variance (ANOVA) with a confidence level of 95 % to find a statistically significant difference. The ANOVA analysis revealed that the friction pressure/friction time ratio had a greater influence on the tensile strength of the joints than the upset pressure/upset time ratio. However, it was found that some of the stainless-steel/aluminium welds had a poor strength due to the accumulation of the alloying elements at the joint interface.Öğe Properties of Al/SiC metal matrix composites(Carl Hanser Verlag, 2018) Sahin, Mumin; Guler, Can; Misirli, Cenk; Cetinarslan, Cem S.; Eisazadeh, HamidMetal matrix composites have higher resistance compared to ceramic and polymer matrix composites. In this study, an aluminum 5754 alloy was fortified using 10 % SiC to obtain a metal matrix composite with properties superior to the original alloy. An improvement of mechanical properties was obtained by reinforcement with aluminum matrix composites which can be produced with various techniques. Mechanical properties of the composite material (Al/SiCp) were initially investigated, and then, the metallurgical properties were determined using an optical metal microscope and SEM. Furthermore, the percent of elongation, tensile strength and Vickers hardness are the input parameters for the mechanical properties. The tensile strength as an output response parameter of Al/SiCp materials was analyzed using experimental Taguchi technique design as an orthogonal array. In the present investigation, experiments were carried out to compare experimental results with predicted optimal values. ANOVA analysis revealed that the percent elongation-PE (%) was the input parameter having the highest statistical influence on tensile strength. It could be shown that the composite material was resistant against both static and dynamic loads. It was also shown that silicon carbide mixed homogenously with aluminum.Öğe Properties of Cold Pressure Welded Aluminium and Copper Sheets(Trans Tech Publications Ltd, 2012) Sahin, Mumin; Misirli, CenkCold pressure welding has been used as an industrial process with an increasing rate for several years. In this study, cold pressure welding has been applied to aluminum and copper alloy sheets having commercial purity. Hydraulic press having 150 metric-ton capacities has been used for welding process. As the surface roughness and the weld deformation ratios of aluminum sheets increased, tensile strength of the joints also increased. Purchased specimens with original roughness had the lowest weld deformation as-is and it was not possible to join these sheets at 30% weld deformations. Hardness increases due to local hardening at the interface as a result of cold deformation. Results showed that the cold pressure welding technique in lap form resulted in strong Al-Al joints and the intermetallic layer formed in Al-Cu joints did not affect the joint strength to a great extent.Öğe RESEARCH ON TRIBOLOGICAL BEHAVIOR OF Cr3C2-25NiCr-COATED BRAKE DISC(World Scientific Publ Co Pte Ltd, 2021) Kilic, Halil; Misirli, CenkThis research presents the results of a comparative study to determine the friction and wear behavior of the high-velocity oxygen fuel (HVOF)-sprayed Cr3C2-25NiCr-coated brake disc. The friction and wear behavior of Cr3C2-25NiCr-coated brake disc (CD) and the sliding against the commercial brake pad were examined on a laboratory-scale disc-pad dynamometer and the findings were compared with those of reference brake disc (UCD). The coating was deposited by means of the HVOF process on a grey cast iron (GCI) substrate. Braking tests were performed according to the SAE-J2430 test standard. The as-sprayed coating was characterized for their microstructure and phase constitution by SEM/EDS and XRD. The results reveal that the coefficient of friction (COF) of CD and UCD varies between 0.42-0.57 and 0.44-0.62, respectively. The Cr3C2-25NiCr-coated brake disc was found to have exhibited a comparable COF and lower wear loss to the reference brake disc. The addition of a ceramic phase to the brake disc coating played an important role in reducing the COF to an acceptable range and improving the sliding wear resistance of the brake pair.Öğe Temperature Determination of St-Al Joints During Friction Welding(Trans Tech Publications Ltd, 2012) Misirli, Cenk; Sahin, Mumin; Kuscu, HilmiThe joining of dissimilar materials is of great importance in industry. Especially, if it is used as the lightest part of the machine parts, materials such as aluminum and magnesium can be joined with steels. Friction welding is one of the methods getting higher share among the other welding methods. In the process, heat is generated by conversion of mechanical energy into thermal energy at the interface of the work pieces during rotation under pressure. Some of the advantages of friction welding are high material save, low production time and being possible of welding of parts which are made by different metals or alloys. Friction welding can also be used in order to join the components that have circular or non circular cross sections. In this study, stainless-steel and aluminum materials which is the example material was used in the friction welding experiments. The temperature distributions are experimentally obtained in the interface of joints that is formed during friction welding of joints having same geometry. This study was made using thermocouples at different locations of joint-interface.
