Browsing by Publisher "Centro Nacional de Investigaciones Metalurgicas"

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    Ultra High Frequency Induction Welding of Powder Metal compacts
    (Centro Nacional de Investigaciones Metalurgicas, 2014) Çavdar U.; Gülşahin I.
    The application of the iron based Powder Metal (PM) compacts in Ultra High Frequency Induction Welding (UHFIW) were reviewed. These PM compacts are used to produce cogs. This study investigates the methods of joining PM materials enforceability with UHFIW in the industry application. Maximum stress and maximum strain of welded PM compacts were determined by three point bending and strength tests. Microhardness and microstructure of induction welded compacts were determined. Copyright: © 2014 CSIC.
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    The evaluation of different environments in ultra-high frequency induction sintered powder metal compacts
    (Centro Nacional de Investigaciones Metalurgicas, 2015) C¸avdar P.S.; C¸avdar U.
    The application of the iron based Powder Metal (PM) compacts in Ultra-High Frequency Induction Sintering (UHFIS) was reviewed for different environments. The three different environments: atmosphere, argon and vacuum were applied to the PM compacts. Iron based PM compacts were sintered at 1120°C for a total of 550 seconds by using induction sintering machines with 2.8 kW power and 900 kHz frequency. Micro structural properties, densities, roughness and micro hardness values were obtained for all environments. The results were compared with each other. © 2015 CSIC.
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    Comparative energy consumption analyses of an ultra high frequency induction heating system for material processing applications
    (Centro Nacional de Investigaciones Metalurgicas, 2015) Taštan M.; Gökozan H.; Taškin S.; Çavdar U.
    This study compares an energy consumption results of the TI-6Al-4V based material processing under the 900 kHz induction heating for different cases. By this means, total power consumption and energy consumptions per sample and amount have been analyzed. Experiments have been conducted with 900 kHz, 2.8 kW ultra-high frequency induction system. Two cases are considered in the study. In the first case, TI-6Al-4V samples have been heated up to 900 °C with classical heating method, which is used in industrial applications, and then they have been cooled down by water. Afterwards, the samples have been heated up to 600 °C, 650 °C and 700 °C respectively and stress relieving process has been applied through natural cooling. During these processes, energy consumptions for each defined process have been measured. In the second case, unlike the first study, can be used five different samples have been heated up to the various temperatures between 600 °C and 1120 °C and energy consumptions have been measured for these processes. Thereby, the effect of temperature increase on each sample on energy cost has been analyzed. It has been seen that as a result of heating the titanium bulk materials, which have been used in the experiment, with ultra high frequency induction, temperature increase also increases the energy consumption. But it has been revealed that the increase rate in the energy consumption is more than the increase rate of the temperature. Copyright: © 2015 CSIC.
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    Effect of Ekabor 2 powder on the mechanical properties of pure iron powder metal compacts
    (Centro Nacional de Investigaciones Metalurgicas, 2016) Altintaş A.; Sarigün Y.; Çavdar U.
    Ekabor 2 powder of different weights, used by V type powder mixture was mixed with pure iron powder. Specimens were created by dry pressing into die followed by cold isostatic press at a pressure of 100 bar for purpose of resizing. The conventional sintering process at 900 °C and 950 °C was carried out for 4 h using conventional furnaces. Specimens were gradually cooled by air. The sintered pellets were examined in terms of density, wear abrasion, surface roughness and hardness at 900 °C and 950 °C. Microstructure of pellets was observed with optic microscope. The results show that the hardness gradually increased with additions of 0 wt. % to 10 wt. % of Ekabor 2 however, after 10 wt. %, this hardness tended to decrease. Copyright: © 2016 CSIC.
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    Consideration of cold metal transfer welding of AA5754 to galvanized steel from mechanical and microstructural aspects
    (Centro Nacional de Investigaciones Metalurgicas, 2018) Çömez N.; Durmuş H.
    In this study, overlap welding of AA5754 and galvanized steel sheets was carried out by cold metal transfer (CMT) method using ER4043 (AlSi5) filler wire. The effect of heat input on the formation of intermetallic compound (IMC) layer between steel and aluminum was investigated. Mechanical properties of the joints were determined by tensile and hardness tests and also applying nano indentation test to intermetallic layer. Chemical compositions of IMC were analyzed by EDX and the formation of Al7.2Fe1.8Si and Fe2Al5 phases was detected. Formation of Fe2Al5 phase was found detrimental for reliability of joint, although it’s superior mechanical strength. © 2018 CSIC.