Browsing by Author "Meriç, C"

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    Investigation of fracture toughness of SAE 1020 welded using rutile covered electrodes, and determination of mismatch factor
    Meriç, C; Okur, A
    The aim of the present work is to examine the yield strength mismatch between the weld metal and the base metal, which affects the deformation and fracture behaviour of welded joints. Specimens prepared from SAE 1020 steel plates were welded using three rutile covered electrodes having different tensile strengths. Fracture toughness of the welded zones was investigated based on the behaviour of cracks caused by fatigue. The mechanical properties of the weld metal and heat affected zone (HAZ) were examined, and graphs were obtained to compare crack progress values Deltaa (mm) and welding material toughness J (N mm(-1)), which is a fracture mechanics parameter. Microhardness investigation was carried out on the weld metal, base metal, and HAZ transitions via measurements along lines on four different zones of the specimen. Micrographs of the specimens were also taken.
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    Effect of material nonlinearity on symmetric aluminum metal-matrix laminated composite beams under a bending moment
    Sayman, O; Çallioglu, H; Meriç, C; Can, N
    In this study, an elastic-plastic stress analysis is carried out on symmetric laminated composite beams subjected to a bending moment. The composite beam is to be strain hardening. The Tsai-Hill theory is used as a yield criterion in the solution. The Bernoulli and Euler hypotheses are assumed to be valid. The beam lay-up sequences are chosen as [90degrees/0degrees](s), [30degrees/-30degrees](s), [45degrees/-45degrees](s), and [60degrees/-60degrees](s). The bending moment starting plastic yielding is found to be highest for [30degrees/-30degrees](s) orientation. sigma(x) residual stress component is found to be highest at the upper and lower surfaces. However sigma(x), residual stress component becomes the highest at the elastic and plastic boundary for further expansion of the plastic region. The transverse displacement is obtained at the free end, numerically.
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    Understanding the thermite welding process
    Meriç, C; Engez, T
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    Elasto-plastic stress analysis of aluminum metal-matrix composite laminated plates under in-plane loading
    Sayman, O; Akbulut, H; Meriç, C
    The study presents an elasto-plastic stress analysis of symmetric and antisymmetric cross-ply, angle-ply laminated metal-matrix composite plates. Long stainless steel fiber reinforced aluminum metal-matrix composite layer is manufactured by using moulds under the action of 30 MPa pressure and heating up to 600 degrees C. A laminated plate consists of four metal-matrix layers bonded symmetrically or antisymmetrically. The first-order shear deformation theory and nine-node Lagrangian finite element is used. The in-plane load is increased gradually. (C) 2000 Elsevier Science Ltd. All rights reserved.
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    Determination of tribological properties at CuSn10 alloy journal bearings by experimental and means of artificial neural networks method
    Ünlü, BS; Durmus, H; Meriç, C
    Purpose - It is important to know the friction coefficient and wear loss for determination of tribological conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. The purpose of this paper is to determine friction coefficient and wear loss at CuSn10 alloy radial bearings by a new approach. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities. Design/methodology/approach - In this study, friction coefficient and wear losses of journal and bearing have been determined by a new approach with a radial journal bearing test rig and artificial neural networks (ANNs) method. The ANN typifies a learning technique that enables the hidden input-output relationship to be mapped accurately. Bronze-based materials have been used as bearing material. Effects of friction coefficient and wear losses have been examined at same load and velocity and at dry and lubricated conditions. Findings - The results obtained in ANN application are close to friction test results for dry and lubricated conditions. Therefore, by using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. Experimental studies will be increased and research with ANN will be continued. Originality/value - By using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. The training finished on 30 min whereas experimental study had continued day after day.
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    Weldability of AL99-SiC Composites by CO2 Laser Welding
    Durmus, H; Meriç, C
    In this study, Al99-SiC composites were produced using PM method. In the composites produced, the reinforcement rates of SiC were 0, 5, 10, and 20 (%wt). The matrix Al 99 powders were mechanically mixed with SiC particulates. These powders were compacted at room temperature at 500 MPa for 5 x 10 x 60 mm specimens and followed by sintering at 600 and 620 degrees C for 1 h. Composite specimens were joined by CO2 laser welding method. Rofin-Sinar SM2000 machine was used for the welding process. The microstructure of melted region was investigated by optical, scanning, and X-ray microchemical analysis techniques. The hardness test, tensile test, and three-point bend test results were presented. The effect to CO2 laser welding method at different reinforcement rates and different sintering temperatures in Al 99 powder was investigated. Because of the lower thermal conductivity of Al99-SiC composites, melting zone is wide. It was observed that 0.5 m/min laser welding velocity was suitable for composites with low SiC rate (0% and 5% SiC), and with increasing SiC (10 and 20%), laser welding velocity of 0.3 m/min was suitable.
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    Experimental microhardness for AA 1030, Cu, CuSn7, CuZn30 and 6114 alloys and a correlation with the Hall-Petch relation
    Meriç, C; Atik, E; Engez, T
    In this experimental study, the strip-formed specimens made from aluminum alloy 1030, pure Cu, CuSn7, CuZn30, and low-carbon steel 6114 were cold worked to different ratios. To determine the microhardness values of the materials, microhardness tests were applied. The grain sizes of the materials were determined by the Heyn method, using a metal microscope. The hardness of materials, H, is dependent on the grain diameter, d, in a way similar to the yield stress in the Hall-Fetch relation H = H-0 + K(H)d(-1/2), where H-0 and K-H are constants. The microhardness of the materials was found, with reasonable accuracy, to vary with grain size according to the Hall-Fetch equation. (C) 2000 Elsevier Science Ltd.
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    Investigation of the effect on boride layer of powder particle size used in boronizing with solid boron-yielding substances
    Meriç, C; Sahin, S; Yilmaz, SS
    In this study, the effect of particle size of powder used in the boronizing process with solid boron-yielding substances on the boride layer was investigated. Hot-shaped AISI 1020, AISI 1030, AISI 1040, and AISI 1050 structural steels were used as the base materials. EKabor HM powder was used as the boronizing agent, and was classified into four groups according to particle size. The boronizing process was carried out with each group at 900 degreesC for 2, 3, 4, and 5 h. The microstructure, microhardness, and layer thickness of the boronized materials were investigated. (C) 2001 Elsevier Science Ltd. All rights reserved.
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    Effect of aging on the abrasive wear properties of AlMgSil alloy
    Meriç, C; Atík, E; Kaçar, H
    In this paper, the wear performance of the aged AlMgSil 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 mu m. 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. (C) 2005 Elsevier Ltd. All rights reserved.
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    The use of neural networks for the prediction of wear loss and surface roughness of AA 6351 aluminium alloy
    Durmus, HK; 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. (c) 2004 Elsevier Ltd. All rights reserved.
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    Age-hardening behavior of powder metallurgy AA2014 alloy
    Durmus, HK; Meriç, C
    The aim of this paper is to investigate age hardening behavior of PM AA2014 alloy. The specimens were made by powder metallurgy (PM) method. During the PM the product was made from powder basic materials by pressing (at 600 MPa) and sintering (600 +/- 5 degrees C, 610 +/- 5 degrees C, 620 +/- 5 degrees C). There were three steps that occur in age-hardening; solution treatment (510 +/- 5 degrees C), quenching (water) and aging (20 degrees C, 150 +/- 5 degrees C, 200 +/- 5 degrees C). Metal microscopy and micro Vickers hardness test were carried out to characterize the structure properties resulting from different aging temperature. The hardness test results showed that the sintering temperature. suitable solution treatment and aging operations has great influence on hardness characteristics of the PM alloys. (c) 2005 Elsevier Ltd. All rights reserved.
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    Effect of aging on abrasive wear of deformable aluminum alloy AA6351
    Meriç, C; Atik, E; Kaça, 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.
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    Effect of loading capacity (pressure-velocity) to tribological properties of CuSn10 bearings
    Ünlüe, BS; Atik, E; Meriç, C
    Bronze is widely used as a journal bearing material for copper-based alloys. These alloys ensure that journal bearings possess the expected properties. These materials that possess tribological properties give good results at journal bearings. In this study, friction and wear properties of journal bearings manufactured by CuSn10 bronze and the effect of p.v. (pressure-velocity) parameter have been examined and compared. SAE 1050 steel shaft has been used as counter abrader. Experiments have been carried out for p. v. values of 0.0125, 0.025 and 0.05 (N/mm s) and for every half an hour totalling to 2.5 h by using radial journal bearing wear test rig. As a result, depending on p.v. values, high friction coefficient and weight loss have been obtained under dry condition more than those obtained under lubricated condition. (c) 2006 Elsevier Ltd. All rights reserved.
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    INVESTIGATION OF TRIBOLOGICAL PROPERTIES CuSn10 BEARING MATERIAL
    Ünlü, BS; Köksal, NS; Atik, E; Meriç, C
    Bronzes which copper based alloys is widely used because of properties physical, thermal and tribological as journal bearing material. This material that has tribological performance good conclusions gives at journal bearings. In this study, CuSn10 bronze that were manufactured journal bearings friction and wear properties has been examined and compared. SAE 1050 steel shaft has been used as counter abrader. Experiments have been carried out 10 N and 20 N loads, 750 and 1500 rpm, dry and lubricated conditions by using radial journal bearing wear test rig. As a results, high friction coefficient and weigh loss have been obtained at dry condition more than lubricated condition.
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    Physical and mechanical properties of cast under vacuum aluminum alloy 2024 containing lithium additions
    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 degreesC, 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 degreesC in 24 h, at 160 degreesC in 16 h, at 190 degreesC in 12 h, and 200 degreesC in 2 h. By increasing the lithium percent, the specific elastic modulus (E/rho) of the alloy increased rapidly but the specific strength (sigma/rho) remained constant. Thus, aluminum lithium alloys that are difficult to manufacture by known methods can be manufactured safely by the vacuum metallurgy method. (C) 2000 Elsevier Science Ltd. All rights reserved.
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    The effects of conventional heat treatment and boronizing on abrasive wear and corrosion of SAE 1010, SAE 1040, D2 and 304 steels
    Atik, E; Yunker, U; Meriç, C
    The effects of conventional heat treatment and boronizing on SAE 1010 and SAE 1040 structural steels, D2 tool steel, and 304 stainless steel were investigated. During this investigation, layer thicknesses, corrosion and wear strength were examined by applying carburisation, nitriding, transformation hardening and boronizing to the specimens. Abrasive wear tests were carried out in a wear cup model device. Sand of 1 mm diameter was used and the test duration was 40 hours with a velocity 0.157 m/s. Corrosion tests were undertaken in a 10% H2SO4 solution at a temperature of 56degreesC. Through metallographic analyses, hard layer thicknesses and Vickers hardness values were determined for each hardening treatment. (C) 2002 Published by Elsevier Science Ltd.
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    Mechanical and metallurgical properties of welding zone in rail welded via thermite process
    Meriç, C; Atik, E; Sahin, S
    The quality of railway construction is an important factor in providing safe and comfortable rail transportation. Thermite welding, which is a long established technique, prevents rail failure and derailing of trains. This technique assists in provding a smooth ride and long service life for rails and railway carriages. In the present study type S49 SAE/AISI 1050 steel rails have been welded via a short preheating thermite process. The hardness distributions of the upper surface and inside sections of the welding zone hare been obtained and its microstructure has heen examined. In addition specimens taken from the upper side (head), web, and base of the welding zone were subjected to tensile and Charpy V notch impact tests. In the hardness profiles for these specimens maximum hardness values were observed at the edges of the weld metal. The hardness values were 109 HB at the interface between the metling zone and the heat affected zone, 108 HB in the melting zone, and 104 HB in the unwelded rail region. Examination of the microstructure revealed proeutectoid ferrite and pearlite, but not martensite.