Konca, Erkan
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Name Variants
Konca E.
K., Erkan
K.,Erkan
Konca, E.
Erkan, Konca
E., Konca
Konca, E
E.,Konca
Konca, Erkan
Konca,E.
K., Erkan
K.,Erkan
Konca, E.
Erkan, Konca
E., Konca
Konca, E
E.,Konca
Konca, Erkan
Konca,E.
Job Title
Doçent Doktor
Email Address
erkan.konca@atilim.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
13
Articles
8
Citation Count
92
Supervised Theses
3
13 results
Scholarly Output Search Results
Now showing 1 - 10 of 13
Article Citation Count: 0Production of 20 mm Thick API PSL 2 X60 and X70 Grade Plates from a Nb-Ti Microalloyed Steel(2020) Konca, Erkan; Metallurgical and Materials EngineeringThis study was undertaken to determine the controlled rolling and cooling conditions for the production of 20 mm thick American Petroleum Institute (API) X60 and X70 grade steel plates. Nb-Ti microalloyed steel slabs of 200 mm thickness were rolled at fourdifferent finish rolling temperatures (conventional, 950°C, 850°C and 800°C). In some trials, a water table was employed to provide accelerated cooling just after finish rolling. Mechanical tests (tensile, impact and drop weight tear-DWTT) and microstructural examinations were performed on the samples taken from the trial production plates. Fine grainedand essentially ferritic microstructures with strength values satisfying the minimum yieldstrength requirement of 415 MPa for the API X60 grade were easily obtained in all rollingconditions. However, the minimum yield strength requirement of 485 MPa for the APIX70 grade was reached only when accelerated cooling was applied after finish rolling. Theminimum 85% shear fracture required by the DWTT of the API PSL 2 specification couldbe met when the finish rolling temperature was lowered or when accelerated cooling wasapplied regardless of the finish rolling temperature.Article Citation Count: 22Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition(Taylor & Francis Ltd, 2014) Konca, Erkan; Karakaya, Ishak; Konca, Erkan; Metallurgical and Materials EngineeringInternal stress in plated deposits has been a common problem that may affect the functionality of coatings. Electrodeposition parameters and insoluble particles modify the characteristics and the level of internal stress of coatings. The influence of the electrocodeposition parameters and their interaction effects on the internal stress during the electrodeposition of Ni and Ni-MoS2 composite coatings were studied by fractional factorial design. The parameters studied and their ranges were: MoS2 particle concentration (0-10 g L-1), temperature (30-50 degrees C), pH (2-4), current density (1.2-4.8 A dm(-2)), and coating thickness (25-50 mu m). MoS2 addition into Watts bath resulted in the decrease in the tensile internal stress values or even changed the stress character from tensile to compressive. Moreover, low stress values were obtained when pH was 2 and coating thickness was 50 mu m.Article Citation Count: 23Effects of Alloying Elements (Mo, Ni, and Cu) on the Austemperability of GGG-60 Ductile Cast Iron(Mdpi, 2017) Konca, Erkan; Tur, Kazim; Tur, Kazım; Metallurgical and Materials Engineering; Department of Metallurgical and Materials EngineeringThe interest in austempered ductile irons (ADI) is continuously increasing due to their various advantageous properties over conventional ductile irons and some steels. This study aimed to determine the roles of alloying elements Ni, Cu, and Mo, on the austemperability of GGG-60 ductile cast iron. Two different sets of GGG-60 (EN-GJS-600-3) samples, one set alloyed with Ni and Cu and the other set alloyed with Mo, Ni, and Cu, were subjected to austempering treatments at 290 degrees C, 320 degrees C, and 350 degrees C. A custom design heat treatment setup, consisting of two units with the top unit (furnace) serving for austenitizing and the 200 L capacity bottom unit (stirred NaNO2-KNO3 salt bath) serving for isothermal treatment, was used for the experiments. It was found that austempering treatment at 290 degrees C increased the hardness of the Ni-Cu alloyed GGG-60 sample by about 44% without causing a loss in its ductility. In the case of the Mo-Ni-Cu alloyed sample, the increase in hardness due to austempering reached to almost 80% at the same temperature while some ductility was lost. Here, the microstructural investigation and mechanical testing results of the austempered samples are presented and the role of alloying elements (Mo, Ni, and Cu) on the austemperability of GGG-60 is discussed.Article Citation Count: 17Investigation of the tribological behaviour of electrocodeposited Ni-MoS2 composite coatings(Inderscience Publishers, 2017) Konca, Erkan; Konca,E.; Karakaya,I.; Metallurgical and Materials EngineeringComposite electroplating of solid lubricants in a metal matrix is an effective way to lower coefficient of friction (COF) and improve wear resistance of surfaces in sliding contact. In this work, Ni-MoS2 composite coatings were deposited on AISI 304 stainless steel substrates by electroplating from Watts bath containing suspended MoS2 particles and their tribological behaviour was studied. The effects of MoS2 particle concentration (5, 10 and 30 g/l), MoS2 particle size (1.440 and 5.156 μm), pH (2, 3 and 4), current density (3.8, 4.8 and 5.8 A/dm2) and the surfactant (sodium lignosulfonate, SLS) concentration (0.3 and 1 g/l) on the tribological behaviour were investigated using a ball-on-disc tribometer at ambient conditions. Lower current density, smaller particle size and higher concentration of MoS2 decreased COF. While increasing the surfactant concentration decreased the COF, its friction lowering effect was much more pronounced at relatively lower concentrations of MoS2 in the electrolyte. Copyright © 2017 Inderscience Enterprises Ltd.Article Citation Count: 8Mechanical behavior of anodic alumina coatings reinforced with carbon nanofibers(Springer, 2009) Konca, Erkan; Konca, Erkan; Sheldon, Brian W.; Jian, Kengqing; Li, Hao; Xia, Zhenhai; Hurt, Robert; Metallurgical and Materials EngineeringAnodic alumina was reinforced with three types of carbon nanofibers differing in the orientation of their graphene structure-perpendicular to the fiber axis, and parallel to the fiber axis both with dense core and hollow core (i.e., nanotubes). This study was designed to identify potential toughening and damage tolerant mechanisms in these nanoscale fiber-reinforced composite coatings. The dense carbon fibers improved contact damage resistance and reduced frictional resistance in sliding contacts. The hollow core reinforcements were much more promising for improving the fracture toughness of the composite coatings.Book Part Citation Count: 0Effect of electroplating parameters on internal stress in ni-m0s2 composite plating(Wiley Blackwell, 2013) Konca, Erkan; Konca,E.; Karakaya,I.; Metallurgical and Materials Engineering[No abstract available]Article Citation Count: 16Investigation of the tribological behaviour of electrocodeposited Ni-MoS2 composite coatings(inderscience Enterprises Ltd, 2017) Konca, Erkan; Konca, Erkan; Karakaya, Ishak; Metallurgical and Materials EngineeringComposite electroplating of solid lubricants in a metal matrix is an effective way to lower coefficient of friction (COF) and improve wear resistance of surfaces in sliding contact. In this work, Ni-MoS2 composite coatings were deposited on AISI 304 stainless steel substrates by electroplating from Watts bath containing suspended MoS2 particles and their tribological behaviour was studied. The effects of MoS2 particle concentration (5, 10 and 30 g/l), MoS2 particle size (1.440 and 5.156 mu m), pH (2, 3 and 4), current density (3.8, 4.8 and 5.8 A/dm(2)) and the surfactant (sodium lignosulfonate, SLS) concentration (0.3 and 1 g/l) on the tribological behaviour were investigated using a ball-on-disc tribometer at ambient conditions. Lower current density, smaller particle size and higher concentration of MoS2 decreased COF. While increasing the surfactant concentration decreased the COF, its friction lowering effect was much more pronounced at relatively lower concentrations of MoS2 in the electrolyte.Master Thesis Termomekanik denetimli haddeleme yöntemi ile API X60 ve X70 sınıfı çelik levha üretimi(2018) Konca, Erkan; Konca, Erkan; Metallurgical and Materials EngineeringBu çalışma, API PSL2 X60M ve X70M sınıflarında çelik levha üretimi için haddeleme ve soğutma koşullarını belirlemek üzere bir ön çalışma olarak gerçekleştirilmiştir. Kimyasal kompozisyonları ilgili API spesifikasyonuna uygun 200 mm kalınlığında iki adet tam boy Nb-Ti-V mikroalaşımlı çelik slab, 14 adet küçük slaba dilimlenmiş ve bu slab dilimlerine 20 mm kalınlığında levha üretmek üzere farklı koşullarda termomekanik haddeleme ve hızlandırılmış soğutma işlemleri uygulanmıştır. Özel olarak; i) bitirme haddelemesi sıcaklığı, ii) toplam ezmenin kaba ve bitime haddelemesi arasındaki dağılımı ve iii) duşlu masa kullanarak hızlandırılmış soğutma uygulamanın etkileri çalışılmıştır. Deneme üretimi levhalardan alınan numunelerin mekanik testleri (çekme, darbe ve düşürme ağırlıklı yırtma deneyi-DWTT) ve metalografik incelemeleri gerçekleştirilmiştir. API PSL 2 kapsamında X60 sınıfı çelik levhalar için istenen mekanik özellikleri karşılayan ince taneli ferritik içyapıların tek başına denetimli haddeleme ile üretilebildiği koşullar belirlenmiştir. Öte yandan, API X70 sınıfı çelik levha üretimi için denetimli haddelemeye ek olarak hızlandırılmış soğutmanın da uygulanması gerekmiştir.Master Thesis KBB yöntemiyle alüminize edilmiş Inconel 718 ve Inconel 738LC süperalaşımların yüksek sıcaklık oksitlenme davranışlarının araştırılması(2022) Konca, Erkan; Konca, Erkan; Metallurgical and Materials EngineeringBu çalışma alüminize edilmiş Inconel 718 ve Inconel 738LC nikel bazlı süper alaşımların yüksek sıcaklık oksitlenme davranışlarını araştırmak ve karşılaştırmak amacıyla gerçekleştirilmiştir. Kaplamasız ve yüksek aktivite kimyasal buhar biriktirim (KBB) yöntemiyle alüminize edilmiş Inconel 718 ve Inconel 738LC numuneler 200 saat boyunca 925, 1000 ve 1050°C sıcaklıklarda havada oksitlenmeye maruz bırakılmıştır. Numunelerin oksidasyon mekanizmalarını araştırmak ve değerlendirebilmek amacıyla detaylı kesit incelemeleri, elementel analizler, ağırlık değişimi ölçümleri ve x-ışını kırınım çalışmaları yapılmıştır. Alüminizasyon sırasında numunelerin yüzeyinde oluşan NiAl fazının üstünde koruyucu Al2O3 tabakası oluşumu sayesinde hem 718 hem de 738LC alaşımında oksidasyon direncinin önemli ölçüde iyileştiği gözlemlenmiştir. Alüminizasyonun faydalı etkisinin tüm test sıcaklıklarında daha düşük oksidasyon hızı gösteren 738LC alaşımı numunelerde daha belirgin olduğu bulunmuştur. 738LC alaşımı altlığın daha yüksek alüminyum içeriğine sahip olmasının alüminyumun NiAl fazından difüzyon yoluyla uzaklaşmasını yavaşlattığı ve böylece bu alaşımın daha üstün oksidasyon direnci göstermesindeki ana neden olduğu öne sürülmüştür.Conference Object Citation Count: 0Effect of electroplating parameters on "HER" current density in Ni-MoS2 composite plating(Minerals, Metals and Materials Society, 2012) Konca, Erkan; Karakaya,I.; Konca,E.; Metallurgical and Materials EngineeringNickel composites with co-deposited insoluble, solid lubricant particles such as MoS2 have been reported to reduce friction. It is known that hydrogen evolution reaction (HER), competes with nickel deposition. The influence of the electroplating parameters and their interaction effects on the peak current density for HER were studied by fractional factorial design. The parameters and their ranges were; MoS2 concentration (0-30 g/l), temperature (30-50°C), pH (2-4) and surfactants (0-1 g/l). Electrodeposition processes were carried out from a typical Watts bath containing leveler, wetting agent and brightener by using a potentiostat. The peak currents (I p) were extended to higher values and the peaks on linear sweep voltammograms became noticeable by increasing the scan rate from 20 mV/s to 100 mV/s over the range 0 to 2.5 V. The peak current densities (ip) for each experimental route were determined by fractional factorial design for three types of mineral processing surfactants; sodiumlignosulfonate (SLS), depramin-C (DC) and ammoniumlignosulfonate (ALS) using Minitab program [1]. Adding MoS2, decreasing temperature and increasing pH has decreasing effect on peak current density for all surfactants. ALS and DC have increasing effect whereas SLS has descending effect on peak current.
