Browsing by Author "Saklakoglu, IE"

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    Mechanical properties and microstructural evaluation of AA5013 aluminum alloy treated in the semi-solid state by SIMA process
    Saklakoglu, N; Saklakoglu, IE; 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 degreesC and 60 min, 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. (C) 2004 Elsevier B.V. All rights reserved.
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    Characterization of austenitic stainless steel after plasma immersion nitrogen and carbon implantation
    Saklakoglu, IE; Saklakoglu, N; Short, KT; Collins, GA
    It has been shown in the literature that plasma immersion ion implantation (PIII) can increase the wear resistance of austenitic stainless steel without losing its corrosion resistance. In this work, the effect of PIII treatment with C ions introduced into the chamber during the process on the tribological properties of AISI 316 L stainless steel has been studied and the results compared. (c) 2006 Elsevier Ltd. All rights reserved.
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    Tribological behavior of PIII treated AISI 316 L austenitic stainless steel against UHMWPE counterface
    Saklakoglu, N; Saklakoglu, IE; Short, KT; Collins, GA
    The aim of this work was to study the tribological benefits of PIII treated austenitic stainless steel by nitrogen ions and/or C ions in a ringer solution, which simulates the environment of the human body. This was achieved by hardness, wear and friction testing, and atomic force microscopy and XRD studies. The results showed that the samples, both treated and untreated, exhibited virtually no wear from contact with the ultra high molecular weight polyethylene (UHMWPE) pins, however, the pins themselves exhibited wear. The amount of wear of the pins was found to decrease with increasing PIII treatment temperature, but addition of C to the chamber caused some increase the amount of wear on the pins. Although C ions reduced to improve the hardness, friction characteristic was improved by formation of carbon-expanded austenite. (c) 2005 Elsevier B.V. All rights reserved.
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    Tribological behaviour of plasma immersion ion implanted AISI 304 stainless steel against polymer and ceramic counterfaces
    Saklakoglu, N; Saklakoglu, IE; Ceyhun, V; Agaçhan, N; Short, KT; Collins, GA
    Type 304 austenitic stainless steel samples were implanted with nitrogen using plasma immersion ion implantation (PIII) at different temperatures between 350 and 500 degrees C. Treated and untreated samples have been studied by wear-friction testing, microhardness measurement and scanning electron microscopy ( SEM). The experimental results indicated that the hardness and wear resistance is improved by increasing the penetration depth of nitrogen, whereas the friction coefficient is significantly increased by PIII.
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    The life of WC-Co cutting tools treated by plasma immersion ion implantation
    Saklakoglu, IE; Saklakoglu, N; Ceyhun, V; Short, KT; Collins, G
    In this study, the tool life of plasma immersion nitrogen-implanted cutting inserts while machining AISI 4140 steel has been investigated. The implantation time was 5 h and the temperature was in the range 320-520 degrees C. Implantation dose was similar to 2 x 10(18) ions cm(-2) for all treatments. Surface topography of the implanted surfaces was obtained from atomic force microscopy. Results of the turning tests are discussed in terms of tool life (flank wear) and surface roughness of the workpieces. The results show that plasma immersion nitrogen implantation increased tool life by about 85%. (C) 2006 Elsevier Ltd. All rights reserved.
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    Formation of Globular Microstructure in A380 Aluminum Alloy by Cooling Slope Casting
    Saklakoglu, N; Gencalp, S; Kasman, S; Saklakoglu, IE
    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, non-dendritic, 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.
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    Sliding wear behaviour of Zr-ion-implanted D3 tool steel
    Saklakoglu, N; Saklakoglu, IE; Ceyhun, V; Monteiro, OR; Brown, IG
    The wear and friction characteristics of zirconium-ion-implanted AISI D3 tool steel have been investigated using pin-on-disc methods. Ion implantation was carried out using a vacuum-arc-based ion implanter to form multicharged zirconium ion beams at a mean ion energy of 130 keV, and the implantation doses investigated were approximately 3.6 x 10(16) 5 x 10(16) and 1 x 10(17) ions cm(-2). It was found that Zr implantation decreased both the wear and the coefficient of friction. The beneficial effects of Zr implantation in terms of associated Auger electron spectroscopy, Rutherford backscattering spectroscopy and scanning electron microscopy microprobe analyses are described. (c) 2006 Elsevier Ltd. All rights reserved.
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    Performance of Fe-based hardfacings on hot forging die: experimental, numerical and industrial studies
    Saklakoglu, N; Irizalp, SG; Dogan, S; Ildas, G; Saklakoglu, IE
    This paper is an investigation into the use of Fe-based alloys as part of wear resistant hardfacing materials in AISI 1.2714 tool steel. Four different weld hardfacing alloys were deposited on 1.2714 steel substrates using tungsten inert gas welding (TIG) process. Wear tests were carried out using a pin-on-disc wear tester at room temperature. Microhardness and micrographs of the weld overlays were obtained. High-temperature properties were estimated by numerical analysis. The phases of the hardfacings were obtained by XRD and also estimated by numerical analysis. The results from the laboratory tests were then compared with the results obtained from field studies. The results showed that some Fe-based alloys improved dies lifetime; others created poor surfaces. A Fe-based hardfacing alloy D which included high C with Cr, W, Mo had the best wear behavior among the weld overlays.