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    A basic study on artificial aging in Mg-10Al(12)Si+1Pb alloy
    (Iop Publishing Ltd, 2020) Cicek, Bunyamin; Aydogmus, Tuna; Sun, Yavuz
    In this study, research has been made on the aging of metal matrix composite materials produced by the in situ casting system. Mg matrix composite material was produced by the in situ casting system. In this study, 90%Mg + 10% Al12Si (wt) ingot casting was performed for alloy formation and 1% Pb was added as an alloying element to the melted structure. This study aims to examine the effect of the artificial aging (AA) process on hardness and microstructure after alloying and composite of Mg metal. The in situ casting system was used in the casting of Mg alloy under the Ar gas atmosphere. The material after required casting homogenization process; for the AA process, they were embedded in a powder graphite filled vessel and kept at 350 degrees C for 1 h and then quenched (with 25 degrees C water). Later; after quenching, the materials were kept at 150 degrees C for 2, 4, 12, 16 and 24 h and aged samples were obtained. Microstructure images were obtained from the samples by scanning electron microscope (SEM) and light optical microscope (LOM) and then the hardness values of the micro hardness device were measured. Grain structure because of AA heat treatment; showed changes according to un-aging material. The hardness value is directly proportional to the increasing aging time of the materials applied to the AA process; it was found that the levels increased approximately to 45% (86HV to 125HV) compared to the un-aging material and passed to the fixing phase.
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    Applicability of different powder and polymer recipes in a new design powder injection molding system
    (Walter De Gruyter Gmbh, 2021) Çiçek, Bünyamin; Sun, Yavuz; Türen, Yunus; Ahlatcı, Hayrettin
    Production methods are changing day by day with the developing technology. Based on this idea, a new production logic and machine have been developed owing to polymer-supported powder injection molding (PIM). The ability of this newly designed machine (newPIM) to mold metal or ceramic powders supported by polymer binders is discussed in this study. By taking advantage of the polymer properties such as fluidity and sticking, powders are molded with a specially developed machine with high gas pressure in certain sizes. In this study, in which many parameters are processed from feedstock (FS) production to molding; metals Mg/316L and ceramics SiC/SiO2 powders have been used in different powder sizes and structures. In the newPIM process, polymers were included in four different recipes. Paraffin wax (PW), polyethylene glycol (PEG), polypropylene (PP), ethylene-vinyl acetate (EVA), poly-methyl methacrylate (PMMA) and low-density polyethylene (LDPE) have been employed in the FS with different combinations. From FS production to the molding stage; pressure, microstructure examination, weight loss, and density change features were investigated. The result indicated that the best FS and molding was obtained by the PEG+PMMA polymer composition formed with a spherical powder with a diameter below 40 mu m. The compression force of the FS in this composition was observed at approximately 3.4k N values.
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    Effects of alloying element and cooling rate on properties of AM60 Mg alloy
    (Iop Publishing Ltd, 2019) Elen, Levent; Çiçek, Bünyamin; Koç, Erkan; Türen, Yunus; Sun, Yavuz; Ahlatcı, Hayrettin
    Magnesium and its alloys have become important structural materials in the last couple of decades due to their exceptional and mechanical properties. In this study, the effects of the introduction Cd, Bi, and Sn alloying elements were introduced into AM60 alloys produced from Mg-Al-Mn triple junction in order to improve the microstructural and mechanical properties. The weight percent of the alloying elements was chosen as 0.5% wt besides the introduction of the additional alloying elements, the effect of cooling rate on microstructural and mechanical properties of the alloys have been investigated. The results showed that the alloying elements introduced to AM60 resulted in an improvement in the mechanical properties of the alloys, which is attributed to the changes in the microstructure. The higher cooling rate led to the formation of the finer a-Mg master matrix which in turn enhanced the mechanical properties of the alloys. It was observed that the intermetallic phase of beta-Mg17Al12 at the grain boundaries became thinner due to the rapid cooling rate and the introduction of the alloying elements, and the continuity decreased and the intergranular distance shortened. The addition of the alloying element increased the tensile strength of the AM60 alloy from 140 MPa to 210 MPa and the elongation values increased from 5% to 22%. The effects of the alloying elements and the cooling rate on the hardness and yields properties of the samples were also studied.
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    Invetigations of mechanical properties after dissimilar steels post-weld of Q345B steel
    (2020) Çiçek, Bünyamin; Aydoğmuş, Tuna; İş, Emine Gündoğdu; Sun, Yavuz
    In this study, it has been reported that Q345B steel combine with different steels using electric arc welding method and the mechanical properties were investigated. Produced by hot rolling processes, Q345B steel is a low-alloyed medium tensile strength and highly usable steel. The steel used contain less than 0.2% carbon and less than 0.55% silicon, chromium and nickel. In this study, Q345B steel generally used at low-pressure/temperature zones in thermal power plant (boiler wall etc.) is combined with 16Mo3 and P265GH steels. The Q345B steel is welded to make the mechanical properties easy to compare. After joining, specimens were collected from the welded areas and used in the preparation of mechanical and metallographic processes. In this process, all joints were subject to tensile, charpy, hardness and bending tests. In addition, the collection of macro images from welding were used in observation of transition zones which were operated. Electrodes with a basic character cover were used (E7018) as filler metal in the joining processes. All mechanical tests met the requirements of the relevant standards and all welds were identified as valid weld.
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    Material Production and the Effect of the System on Biocompatibility in the Modified Metal Injection Method
    (POLSKA AKAD NAUK, POLISH ACAD SCIENCES, INST METALL & MATER SCI PAS, 2023) Çiçek, Bünyamin; Sun, Yavuz
    In this study, the bio state of the alloy produced in the modified metal injection system was monitored after sintering. A new system operating with high gas pressure, far from the traditional injection model, has been established for material production. In this system, 316L stainless steel powders were molded using a PEG/PMMA/SA polymer recipe. During molding, approximately 60% 316L and 40% binder by volume were used. The samples obtained were sintered at different temperatures (1100-1300°C) after de-binding. Density measurement (Archimedes) and hardness tests (HV1) of the samples were measured as 6.74 g/cm3 and ~285 HV1, respectively. A potentiodynamic corrosion test was applied to monitor the effect of the amount of oxide in the structure of the 316L stainless steel produced. Corrosion tests were carried out in artificial body solutions. The corrosion rate was measured at the level of 17.08×10–3 mm/y. In terms of biocompatibility, a cytotoxicity test was applied to the samples and the life course of the bacteria was monitored. For the 316L alloys produced, the % vitality reached approximately 103%.