Browsing by Author "Gencalp S."

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    Semisolid microstructure evolution during cooling slope casting under vibration of A380 aluminum alloy
    (2010) Gencalp S.; Saklakoglu N.
    This study is concerned with the influence of the vibration at a specific frequency to the inclined plate during cooling slope casting. A380 aluminum alloy was employed in the present work. The alloy was poured from the inclined plate with an angle of 60and a length of 500mm at a pouring temperature of 630C. The pouring was carried out on an inclined plate with and without vibration. Microstructures of specimens obtained from both conditions were examined. Grain size analysis of specimens was carried out. Experimental results showed that the application of vibration affected the microstructure. Hence, it was determined that the application of vibration increased the nucleation and led to more breaking of dendrite arms. In this study, the convection of melt by vibration played an important role on formation of non-dendritic primary Al-particles. Copyright © Taylor & Francis Group, LLC.
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    Microstructural evolution and mechanical properties of cold-deformed al-5cu alloy samples after isothermal heat treatments
    (2010) Saklakoglu N.; Gencalp S.
    Abstract.In this paper, the microscopic morphology of a semi solid Al5Cu alloy by strain induced melt activated (SIMA) process were investigated, and the effects of predeformation, microstructural evolution, aging response and hardness changes were determined. The microstructural observation shows that while the grain boundaries started to appear after 620°C, globular grains surrounded wet boundaries needed for SSP were obtained at 650°C. The grain sizes exhibited ununiformity from the outer surface to the center of the sample because of ununiform predeformation. Although isothermal heat treatments reduced hardness, age hardening gave back the hardness loss. © 2010 American Institute of Physics.
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    Formation of globular microstructure in A380 aluminum alloy by cooling slope casting
    (2011) Saklakoglu N.; Gencalp S.; Kasman S.; Saklakoglu I.E.
    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, nondendritic, 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. © (2011) Trans Tech Publications, Switzerland.
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    The effects of cooling slope casting and isothermal treatment on wear behavior of A380 Alloy
    (2011) Saklakoglu N.; Gencalp S.; Kasman S.
    In this study, A380 aluminum alloy feedstock produced with cooling slope casting was exposed to isothermal treatment to obtain a globular microstructure which is a key feature for semisolid forming. The dendritic primary phase in the conventionally cast A380 alloy has readily transformed into a non-dendritic one in ingots cast over a cooling plate from pouring temperatures between 615, 630 and 650 °C. After the casting process, isothermal treatment was carried out at 565 °C in induction unit. Isothermal treatment yields a globular microstructure. To determine the tribological properties of this alloy, a pin-on-disc tribometer was used to carry out tribological tests under dry sliding conditions. The results showed that both cooling slope casting and isothermal treatment has an effect on tribological properties. © (2011) Trans Tech Publications, Switzerland.
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    Effects of Low-Frequency Mechanical Vibration and Casting Temperatures on Microstructure of Semisolid AlSi8Cu3Fe Alloy
    (Springer Verlag, 2012) Gencalp S.; Saklakoglu N.
    This paper is concerned with the influence of vibration on the cooling slope casting and gravity casting. Mechanical vibration during cooling slope casting is a new technique. Also isothermal holding period of hypoeutectic Al-Si alloy to prepare semisolid slurry has been studied. The convection caused by the vibration during solidification had remarkable effects on the formation of spherical α-Al particles. The main vibration effects include evolution and increase of nucleation and thus reducing as-cast grain size; globularization of particles and production of a more homogenous metal structure. In this work, mechanical mould vibration and mechanical-inclined plate vibration was applied to an AlSi8Cu3Fe alloy at fixed frequency. Metallographic examinations and grain analysis were done on specimens obtained with different pouring temperatures and casting methods. The α-Al particles were spherical in cooling slope casting under vibration, as compared with cooling slope casting without vibration and gravity casting with vibration. A grain analysis along with different casting techniques was performed in order to understand the vibration effect. A heat-transfer mechanism seems responsible for the vibration effect in grain formation. © 2012 King Fahd University of Petroleum and Minerals.