Yazar "Tekeli, Suleyman" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    THE EFFECT OF DIFFUSER AND NON-DIFFUSER RUNNER SYSTEMS ON THE MECHANICAL PROPERTIES OF A356 ALLOY
    (Gazi Univ, Fac Engineering Architecture, 2013) Tuncay, Tansel; Tekeli, Suleyman; Ozyurek, Dursun
    In this study, runner systems which have equal cross-sectional area and different forms of cross-sectional diffuser and non-diffuser runner system's effects on mechanical properties of A356 aluminium alloy, depending on the movement of the liquid metal, were investigated. The aim of the study is to reduce casting defects due to inclusion caused by runner systems such as gas or shrinkage porosity. Therefore, the horizontal runners have been extended by using diffusers having cross-sectional area equivalent with a different cross-sectional shape (square, rectangular and circular outlet). Tensile test specimens were prepared from the plates of casting A356 alloy and tensile tests were performed. Obtained results were examined Weibull statistical analysis. As a result, one hand, it is observed that the turbulence effect on liquid metal has been decreased the highest tensile results and Weibull modulus has been appeared on the samples which have horizontal runners produced by using a square section diffuser in designed horizontal diffuser. On the other hand, according to Scanning Electron Microscope (SEM) analysis on fracture surfaces, fracture has been observed in the area of intermetallic secondary phases (oxides etc.) and in area with gas or shrinkage porosity.
  • Küçük Resim Yok
    Öğe
    The Effects of Cr and Zr Additives on the Microstructure and Mechanical Properties of A356 Alloy
    (Springer India, 2020) Tuncay, Tansel; Ozyurek, Dursun; Dispinar, Derya; Tekeli, Suleyman
    This study has investigated the effect of different amounts of Cr and Zr additions on the microstructure and mechanical properties of A356 alloy modified with strontium. The microstructure and phase examination were performed using an optical microscope, scanning electron microscope and XRD analysis, whereas mechanical properties were investigated via tensile testing and hardness measurements. Two-dimensional Weibull distribution was used to determine the effect of Cr and Zr additions on mechanical properties of A356 alloy. It was found that the most significant effect of Cr and Zr added was over the morphology of Al-Si-Fe intermetallics. The addition of Cr and Zr led to the formation of Cr/Zr-based intermetallics in precipitates and fish-bone-like morphologies. It was observed that increasing the amount of Cr and Zr had resulted in an increase in ductility of A356.
  • Küçük Resim Yok
    Öğe
    Effects of Different Solid Solution Temperatures on Microstructure and Mechanical Properties of the AA7075 Alloy After T6 Heat Treatment
    (Walter De Gruyter Gmbh, 2019) Tekeli, Suleyman; Simsek, Ijlal; Simsek, Dogan; Ozyurek, Dursun
    In this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120 degrees C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.
  • Küçük Resim Yok
    Öğe
    Microstructure-bifilm interaction and its relation with mechanical properties in A356
    (Taylor & Francis Ltd, 2017) Tuncay, Tansel; Tekeli, Suleyman; Ozyurek, Dursun; Dispinar, Derya
    Cooling conditions and inclusions are of the most important factors that affect mechanical properties of cast aluminium alloys. This study investigated the effect of secondary dendrite arm spacing (SDAS) on the shape of pores (i. e. bifilm unravelling) and the mechanical properties of cast A356 alloy. Different cooling conditions were established by electrolytic copper chill, H13 steel chill and insulated ceramic that was placed in the mould cavity. SDAS and shape of pores were investigated by optical microscopy. The fracture surfaces of tensile test samples were analysed by SEM and EDX. Weibull two-parameter statistical method was used to assess the tensile properties. Results show that mechanical properties were dominantly affected by pore morphology that was formed by bifilms. Increasing the cooling rate (i. e. decreasing SDAS), the unravelling of bifilms delayed which decreased porosity formation significantly.
  • Küçük Resim Yok
    Öğe
    Wear Properties of Titanium and Ti6Al4V Titanium Alloy by Mechanical Milling
    (Walter De Gruyter & Co, 2011) Ozyurek, Dursun; Tekeli, Suleyman
    In this study, wear characteristics of titanium and titanium alloyed materials produced with mechanical alloying/milling (MA/MM) method were studied. In production of titanium and titanium alloyed materials, sponge titanium, gas atomised titanium powder and pre-alloyed Ti6Al4V alloy powder were used. The produced materials were characterised by scanning electron microscope, optical microscope, X-rays diffractometer (XRD) and EDS. The wear tests were carried out on a pin-on-disc type wear device under three different loads (15-30-45 N), four different sliding distances (500-1000-1500-2000 m) and a sliding speed of 1 ms(-1). The results showed that no porosity was found on the gas atomised titanium and the Ti6Al4V alloy while very low amounts of micro porosity were formed on the sponge titanium samples. EDS analysis, on the other hand, revealed some Fe contamination on the materials, arising from the milling environment. It was seen that the hardness values of the samples produced from the gas atomised titanium powder were higher either than the samples produced from the sponge titanium, or the samples produced from the Ti6Al4V alloy. The fact that the wear losses obtained for the samples produced from the TiAl4V and gas atomised titanium powders were lower when compared to the sponge titanium. This was considered as the result of porous structure of sponge titanium.