Papers by Author: Ahmet Güral

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Authors: Ahmet Güral, Süleyman Tekeli, Dursun Özyürek, Metin Gürü
Abstract: The effect of repeated quenching heat treatment on microstructure and dry sliding wear behavior of low carbon PM steel was investigated. For this purpose, atomized iron powder was mixed with 0.3 % graphite and 1 % Ni powders. The mixed powders were cold pressed and sintered at 1200°C for 30 min under pure Ar gas atmosphere. Some of the sintered specimens were intercritically annealed at 760°C and quenched in water (single quenching). The other sintered specimens were first fully austenized at 890°C and water quenched. These specimens were then intercritically annealed at 760°C and re-quenched in water. The martensite volume fraction in the double quenched specimens was higher than that of the single quenched specimen. Wear tests were carried out on the single and double quenched specimens under dry sliding wear condition using a pin-on-disk type machine at constant load and speed. The experimental results showed that the wear coefficient effectively decreased in the double quenched specimen.
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Authors: Süleyman Tekeli, Ahmet Güral, Metin Gürü
Abstract: The effect of tempering temperature and microstructure on dry sliding wear behavior of quenched and tempered PM steels was investigated. For this purpose, atomized iron powder was mixed with 0.3 % graphite and 1-2 % Ni powders. The mixed powders were cold pressed and sintered at 1200°C. The sintered specimens were quenched from 890°C and then tempered at 200°C and 600°C for 1 hr. Wear tests were carried out on the quenched+tempered specimens under dry sliding wear conditions using a pin-on-disk type machine at constant load and speed. The experimental results showed that the wear coefficient effectively increased with increasing tempering temperature. With increasing Ni content, the wear coefficient slightly decreased at all tempering temperatures due to the high amount of Ni-rich austenitic areas.
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Authors: Metin Gürü, M. Korçak, Süleyman Tekeli, Ahmet Güral
Abstract: The properties of ceramic-metal (Cermet) composites as tensile strength, hardness and resistance to corrosion and high temperature are superior than ceramics and metals. Because of the enhanced characteristics of cermets, they are commonly used in various applications and industries. The main objective of this study is to produce a cheap, easy produced, strong and high corrosion resistant composite material. For these purposes, zinc is used for its natural capacity against corrosion, low density, low melting point and softness. Magnesium aluminates spinel oxide (MgAl2O4) is chosen because of its high melting point and low density. Fly ash is a waste from coal power plant having puzzolanic properties. In this study, the effect of various amounts of zinc and fly ash addition on density and hardness behaviour of zinc-based MgAl2O4 composites was investigated. The experimental results showed that zinc and fly ash addition improved the hardness behavior of zincbased MgAl2O4 composite.
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