Neset Akar

• Doctor of Engineering
• Gazi University

This study investigated the effect of cerium (Ce) addition (0.5 and 1 wt.-%) on the microstructure, mechanical properties, and dry sliding wear behavior of AM50 magnesium alloy produced by high-pressure die casting (HPDC). A tribometer was utilized to conduct a dry sliding wear test with different sliding speeds (0.5 m.s-1, 1 m.s-1, 1.5 m.s-1, and...

This study investigates the effect of the austempering temperatures on the microstructures and mechanical properties of austempered ductile iron with dual-matrix structure (DMS-ADI). An unalloyed ferritic ductile iron bar samples were intercritically austenitized at 810 °C for 60 min and austempered at different austempering temperatures (300 °C, 3...

This study investigates the influence of post-oxidation duration on the wear performance and microstructural features of AISI 4140 steel subjected to nitrocarburizing followed by post-oxidation. For this aim, the quenched and tempered AISI 4140 samples were nitrocarburized (NC) and post-oxidized (PO) at various times (45–180 min) under low vacuum....

This study investigates the effect of two-step solution treatments and aging times on the microstructure and mechanical properties of B357 Al–Si alloy, part of the most widely used cast aluminum alloy. Three sets of artificial aging heat treatments were conducted on the tensile samples prepared from B357 alloy produced by low-pressure die casting....

This study investigated the microstructure and mechanical properties of the recycled Ti6Al4V alloy produced using the waste chips vacuum arc melting (VAM) process. The waste chips were cleaned to remove machining residues before VAM and dried in the oven. The dried and compressed chip compacts are vacuum arc melted and hot rolled. Microstructural c...

In this study, the wear behavior of AA7075 alloy produced by thixocasting was investigated. The wear behavior of the AA7075 alloy is examined for three cases: extruded with T6 heat treatment, as-thixocast, and thixocast with T6 conditions. The dry sliding wear test was conducted with a tribometer according to ASTM G-99 standard. The microstructures...

In this study, three-dimensional (3D), biodegradable, porous magnesium (Mg) alloy scaffolds were fabricated using the rapid casting method. The casting models were welded onto a wax rod to produce a casting tree using a stereolithography (SLA) machine with castable wax. The model has a high surface area and porosity. The pore size, strut thickness,...

In this study, the effect of casting parameters on microstructure and mechanical properties of Co-Cr-Mo superalloy dental blocks produced by centrifugal investment casting method was investigated. In addition, the effects of atmosphere environment and carbon content were investigated during casting processes. After the casting process, metallograph...

Effects of melt stirring and holding time were studied with an Al-4.5 % of mass fractions of Cu (A206) alloy. The optimum level of a grain refiner was determined in conjunction with both continuously stirred and non-stirred melts during the holding time. Results showed that a mass fraction of a Ti addition of as low as 0.03 % was sufficient to obta...

Tensile fracture behaviors of thixocast, artificially aged thixocast (thixocast+T6) and as-extruded AA7075 alloys were investigated. The microstructural and fractographic observations were carried out using optical microscope (OM) and scanning electron microscope (SEM). Experimental studies showed that as-extruded and thixocast+T6 specimens exhibit...

In this study, the effects of injection velocity on tensile properties and hardness of A357 aluminum alloy produced by thixocasting process were investigated. For this purpose, feedstock produced by cooling slope process were first held at reheating temperature of 572 °C and then formed at injection velocities of 1, 1.5, 2 and 2.37 m x s-1, respect...

In this study, a wrought Al2024 aluminum alloy formed with thixocasting method which is one of the semi-solid metal forming processes and the effect of liquid fraction and aging heat treatment (T6) on microstructure an mechanical properties has been investigated. Billets produced by strain induced melt activation (SIMA) process were used in thixoca...

Bu çalışmada, T6 yapay yaşlandırma ısıl işleminin tikso dökümle şekillendirilmiş AA7075 alüminyum alaşımının mikroyapısı üzerine etkisi araştırılmıştır. Gerinimin neden olduğu sıvı aktivasyonu (SIMA) işlemi ile üretilen numuneler yüksek basınçlı döküm makinesi kullanılarak tikso dökümle şekillendirilmiştir. Numuneler daha sonra çözündürme işlemi so...

Bu çalışmada, Al-Zn esaslı dövme alüminyum alaşımında ekstrüze halden tiksotropik yapı üretimi araştırılmıştır. Bu amaçla, 40 mm çapında ve 40 mm yüksekliğindeki biyetler üç farklı sıvı oranına (%30, %40 ve %50) karşılık gelen sıcaklıklara indüksiyonla ısıtmanın ardından suda soğutularak mikroyapı değişimleri incelenmiştir. Deneysel çalışmalar, ar...

The heat transfer coefficient on the casting-mold interface is an important factor which determines the structural and mechanical properties of the casting, and controls the solidification rate of the casting. It is affected by many parameters such as surface roughness, mould material, type of alloy, direction of solidification, mould and casting t...

The microstructural features of casting defects in a thixocast AA7075 alloy were investigated in the present work. Microstructural examinations were conducted by using scanning electron microscope. It was observed that the presence of micro shrinkage at dendritic solidified region and microsegregation at grain boundaries. Hot tears were determined...

In this study, the production of required thixotropic microstructure for the semi-solid forming in a wrought aluminium alloy AA2024 was investigated by strain induced melt activated (SIMA) method. For this purpose, AA2024 alloy as extruded state were subjected to cold deformation at %20 rate, and then reheated to different semi-solid temperatures w...

In this study, thixotropic microstructure produced in a wrought AA2024 alloy for the semi-solid forming was investigated by strain induced melt activated (SIMA) method. For this purpose, AA2024 alloy as extruded state were subjected to cold deformation at different rates, following heated to a semi-solid region, and cooled in water at room temperat...

In this article, the interfacial heat transfer coefficient (IHTC) is investigated as a function of superheat temperatures (100°C, 150°C, and 200°C) and casting heights (100, 150, and 200 mm). The experiments were conducted for a liquid alloy (Al-Si 12.9%) on water-cooled copper chill during vertically upward solidification of a eutectic Al-Si alloy...

The objective of the present work was to investigate the effect of silicon content on the interfacial heat transfer coefficient (IHTC) for vertically upward unidirectional solidification of Al-Si casting on water cooled cupper chills during solidification. The interfacial heat transfer coefficient measured as a function of different silicon content...

In this study, the interfacial heat transfer coefficient (IHTC) for vertically upward unidirectional solidification of a eutectic Al–Si casting on water cooled copper and steel chills was measured during solidification. A finite difference method (FDM) was used for solution of the inverse heat conduction problem (IHCP). Six computer guided thermoco...

The interfacial heat transfer coefficient plays an important role in the rate of heat transfer from the metal to the mould. The macro and microstructures of castings are mainly related on the heat transfer rate. The objective of the present work was to investigate the effect of surface roughness of chill on the interfacial heat transfer coefficient...

In this study, physical properties of a commercial investment casting sprue wax (B97) have been improved by the addition of some additives so that it can be used as a pattern wax. For this purpose, some chemicals and soybeans of different varieties, which their positive effects on the properties of B97 had been observed in our previous studies, hav...

In this research, modifying effects of some soybeans on the properties of an investment casting sprue wax (B97) have been studied. For this purpose, soybeans of Wilken-3480, NS-6, RHS-6592 and SGI-3308 varieties have been used as the additives. The effects of these soybeans on the surface roughness, solidification shrinkage, viscosity, hardness, te...

In this research, the properties of a commercial investment casting sprue wax (B97) were modified to improve its properties so it can be used as a pattern wax in investment casting. For this purpose, some colloids (gum arabic, pectin, agar, polyvinylpyrrolidone-40, polyvinylpolypyrrolidone, alginic acid, cellulose, carboxymethyl cellulose, silicon,...

ZET Sıvı metalin temizlenmesi için bir çok yöntem kullanılmaktadır. KGDD'de kirliliklerin bulunması mekanik özellikleri ciddi şekilde azaltabilmektedir. KGDD'den filtrasyon yoluyla inklüzyonların giderilmesi gelişmiş mekanik özellikler sağlamaktadır. Filtrasyon için birçok farklı tip filtreler bulunmaktadır. Bu çalışmada filtrasyon işleminde serami...