Browsing by Author "Meric, C"

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    Determination of hardness of AA 2024 aluminium alloy under ageing conditions by means of artificial neural networks method
    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.
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    An investigation of the weld region of the SAE 1020 joined with metal active gas and determination of the mismatch factor
    Meric, C; Tokdemir, M
    In this study, the joining process of SAE 1020 low carbon steel, generally used in the industry, has been completed using the metal active gas (MAG) weld method. The goal of this study was to examine the mismatch between base and weld metal. After the joining process, mechanical properties of the samples of the base metal (BM), the heat affected zone (HAZ), and the weld metal (WM) were investigated, and the crack tip opening displacement (CTOD) test was performed.
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    Investigation of the boronizing effect on the abrasive wear behavior in cast irons
    Meric, C; Sahin, S; Backir, B; Koksal, NS
    One of the methods used to improve the surface properties of iron and steel is boronizing. Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by pack-boronizing method. Commercial EKabor (R) 3 powder was used as the boronizing agent and the treatment was carried out at 900 degrees C for 2, 3, 4, 5 and 6 h. Thickness, microhardness and microstructure of the boride layer are investigated. Abrasive wear behavior of the boronized and unboronized cast irons were investigated. For this purpose, the specimens were tested on a pin-on disk test apparatus. SAE 1040 steel was used as the moving surface member. Abrasive wear tests were carried out at a fixed load and a fixed sliding speed. The weight loss was measured and worn surfaces were examined. (c) 2005 Elsevier Ltd. All rights reserved.
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    Investigation of the effect of boronizing on cast irons
    Sahin, S; Meric, C
    Gray iron, ductile iron and compacted graphite iron were boronized with solid boron-yielding substances by box-boronizing method. Commercial EKabor(R)3 powder is used as the boronizing agent and the treatments are carried out at 850, 900 and 950degreesC for 2, 3, 4, 5 and 6 h. Thickness and microhardness of the boride layer, and the microstructure of the boronized specimens are reported. (C) 2002 Elsevier Science Ltd. All rights reserved.
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    The Portevin Le Chatelier effect in Al-alloys with Cu, Mg and Li
    Meric, C
    Serrated yielding properties of aluminum alloys with copper, magnesium and lithium were investigated. 2024, 2014, 7075, AlCu4Ti and 2024 containing lithium additions aluminum alloys were used. Melting was carried out in an induction furnace under argon gas protection, the casting is done under vacuum. To obtain the maximum strength and hardness, the specimens were solution heat-treated fewer than 495 degrees C and quenched in water at room temperature. They were then aged naturally and artificially. The specimens were aged naturally at room temperature in one week or artificially at 120 degrees C in 24 hours. All the specimens were subjected to tension tests. The strain rates were 0.521, 1.042 and 5.208 respectively. For a strain rate of 1,042 10-3 s(-1), serrated yielding was observed.
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    The effect of precipitation-hardening conditions on wear behaviours at 2024 alurninium wrought alloy
    Kacar, H; Atik, E; Meric, 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 I week, at 120 degreesC for 24 h, at 150 degreesC for 18 h, at 160 degreesC for 16 It, at 200 degreesC for 2 h) was worn in pin-on disc model wear test apparatus using different abrasive grit size (5, 11, 18 and 30 mum SiC papers). Furthermore, the effects of different sliding speeds (0.078, 0.156, 0.208 and 0.338 in s(-1)) and loads (6.45, 9, 9.3 and I I N) 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. (C) 2003 Published by Elsevier B.V.
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    An investigation on the elastic modulus and density of vacuum casted aluminum alloy 2024 containing lithium additions
    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 merited 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/rho, ratio increases by about 10% for each 1% addition of lithium.
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    Investigation of effect of boronising on welding zone
    Meric, C; Sahin, S; Uzkut, M
    In the present studY, AISI 1040 and AISI 8620 steels are joined by arc welding and gas metal arc welding, and then subjected to a solid boronising process at 850, 900, 950, and 1000degreesC using EKabor Hill (trade-name) for 4 h. The microhardness and thickness of the boride layers produced on the surfaces of the air cooled specimens are measured and the microstructures are photographed using optical microscopy. The effect of boronising in and around the welding zone is investigate.
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    Production of ferroboron powders by solid boronizing method
    Sahin, S; Meric, C; Saritas, S
    Ferroboron is an iron-boron alloy containing 10-20% of boron by weight. Commercial ferroboron production is made by two main processes: carbothermic reaction and aluminothermic reaction. Ferroboron also occurs in steel surfaces due to boronizing, which is applied to increase surface hardness in steel. Boronizing is a thermo-chemical surface hardening treatment. The ferroboron phases like Fe(2)B, FeB form by diffusing of boron element into iron. These phases are very hard, wear strengths are high, and friction coefficients are low. In this study, ferroboron powder was obtained by boronizing ASC 100.29 iron powder that was used widely in powder metallurgy area. Solid boronizing method was preferred due to its advantages in applications and Ekabor-HM powder was used as the boronizing agent. The 80% ASC 100.29 and 20% Ekabor HM were mixed homogeneously and subjected to boronizing at 850-950 degrees C for 1-6 h. Formation and development of ferroboron phase on the samples was determined by metallographic studies depending on various treatment conditions. The X-ray diffraction analysis revealed that the Fe(2)B phase did form but FeB phase did not. Micro hardness distributions were measured on the powder grains. Eighteen GPa hardness was measured at Fe(2)B phase obtained by boronizing while hardness of non-boronized iron powders was 1.06 GPa. The thickness of ferroboron layer formed by boronizing changed with boronizing conditions. The thickness of ferroboron layer increased with boronizing temperature or boronizing time. Depending upon processing parameters, ferroboron layers was formed partially or throughout ferrous powder structure. Since boronizing can be applied to iron powders having any size or shape, ferroboron production with required shape and size is possible. Finally, a new method, namely solid boronizing method, was developed in ferroboron powder production. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.