SEARCH RESULT

This study includes device design and design for determining the performance of rigid round thin wires under a bending rotating fatig load over a given lifetime. Small diameter wires are thin wires with a diameter equal to or greater than 1.60 mm (0.63 inch). Bending rotating fatig tester ensures that the wire is rotated at constant speed and subjected to constant amplitude bending deformation. For this purpose, the wire retaining pliers are parallel to each other and the wire between the pliers is 180° paralel. After the speed is entered to the driver, the AC motor power is started by means of the belt-pulley and then transferred to the gears with the help of the cardan shaft. The number of cycles is transmitted to the counter by the encoder and recorded. The number of cycles can be generated in response to the bending deformation applied. The test device was reproducible and healthy.

International Iron & Steel Symposium
UDCS

Emre Demirci Hayrettin Ahlatçı Yavuz Sun Yunus Türen Hüseyin Koymatcık

—In the aim of this study; the determination of life in steel materials used in different temperature conditions in thermal power plants has been conducted. In these systems, basic steels with low C levels are use at low temperatures and Cr-Mo added special series steels are use at high temperatures. In cases where the creep resistance is of great importance, the choice of material according to the level of creep resistance comes to the fore. In the industry, non-destructive testing methods have been develop in order to conduct investigations in the actively working systems. There are many volumetric and superficial tests in welded joints. In the non-destructive tests carried out on the material, with replica microstructure copying and mobile measurements come to the fore. In this study, the determination of life of ASTM SA192 quality steel materials, which a reactive at low temperatures, has been studied. Replica microstructure was replicate through a working system and the images were compare according to the first material. Because of this comparison, changes in material microstructure were determined as grain growth. Hardness and thickness values obtained by mobile devices were also exam according to the first material. As a result, 338C temperature and 39 bar internal pressure in the working material, because of 140000 hours, a 17% reduction in thickness and hardness (HB) was seen a decrease of 21%.

International Iron & Steel Symposium
UDCS

Bünyamin ÇİÇEK Yavuz Sun Hayrettin Ahlatçı Yunus Türen

In this study, up to 38ppm of boron was added to 4140 steel and the effects of this addition on microstructure and tribocorrosion were investigated. Tribocorrosion behavior was investigated in a 3.5% NaCl solution with a pin on disc method. As a result of the studies, it was found that the hardness and tribocorrosion behavior increased with the addition of boron but these values decreased with the increase in boron amount after 17ppm.

International Iron & Steel Symposium
UDCS

Tayfun AKSOY Engin ÇEVİK Hüseyin DEMIRTAS Yavuz Sun Cemal ÇARBOĞA

Material conditions are very important in systems operating at high vapor pressure and temperatures. Cr-Mo series special steels used in the thermal power plants of such structures have high creep resistance and long lasting materials. The time from the first production phase to the usage area and subsequent welded joint processes should be carefully monitor. The P91 and P92 series are the highest-grade creep resistance of the steels mentioned in different standards. All stages of these steels should be keep under control. Otherwise, they cannot meet the desired efficiency after welding. In our study, the whole process for the P91 steels from the beginning of the weld to the end is summary as a technical report. For P91 materials, the requirements for pre-welding, welding and post-welding are explain together with the academic data. Many studies on materials P91 have been compile and tried to form a technical guide.

International Iron & Steel Symposium
UDCS

Bünyamin ÇİÇEK Yavuz Sun Hayrettin Ahlatçı Yunus Türen

— Cr-Mo steels with high creep resistance used in power generation plants vary according to the region where they are used. As the temperature and pressure increase, the amount of CrMo increases in the alloy. The welding of these dissimilar steels is obligatory in the regions that make up the temperature difference. For example, when P91 quality steels are use at high temperatures, P22 quality steels are use at lower temperatures. In the transition from the walls of the boiler to the outside, these two dissimilar steel are weld together. In such processes, all stages before and after the welding should be keep under control. In this welding process, relevant standards should be follow and witnessed sample (PQR) must be perform prior to welding. After that, the weld are valid, which meet the desired values from the mechanical tests (when the values of the standards are meet). A PQR study was follow in our study. In this weld, P91-P22 coupling was make by TIG method. Afterwards, tensile, bending, charpy and hardness tests were apply according to the relevant standards and it was observe that they met the standard requirements.

International Iron & Steel Symposium
UDCS

Bünyamin ÇİÇEK Yavuz Sun Mehmet Ünal

Powder metallurgy method is production of parts widely used today. This use is widely used in many areas of the steel materials industry, especially from powder metal parts produced by powder metallurgy method. Since these materials take the form of the final product at the end of production without requiring any machining process. Also, these materials can be used as an iron based bearing material because of the machine parts such as filter, cutting tool bits and they have self-lubricating property due to its porosity. The aim of this study is; stainless steel matrix, boron carbide reinforcement in different ratios (5%, 10%, 15%) is the production of functional graded material. For this reason, stainless steel and boron carbide powders were mixed in V-type mixer for 3 hours. After this process, the samples were produced by means of powder metallurgy under pressure of 45 MPa at 900°C in the hot press machine. The microstructure and boron carbide distribution of the produced samples were examined in the SEM device and hardness measurements were made in order to observe the changes in mechanical properties. When microstructures were examined, it was determined that boron carbides were distributed homogeneously. It was observed that the hardness increased as the rate of support and the transition between the stages increased.

International Iron & Steel Symposium
UDCS

Batuhan Özusta Yasin Akgül Hayrettin Ahlatçı Süleyman Yaşın İsmail Esen Yavuz Sun Yunus Türen

—In this study for a teeth wire that has a quality of 316, diameter of 0.4 mm and a tensile strength of 800 MPa, we investigated its fatigue behaviour in two environments: atmosphere and 3,5% NaCl using the methods of simple bending tests. In order to do those tests we decided to use stainless steel braces of model REF500-040-00 and calculated the wire’s length before starting the test using the following law: (L = (c * 2.17) +31). The tests have been done according to the room temperature and frequency of 10 Hz. We used the lean bias device to perform the test which requires the fully reversible stress (R=min/ max= −1). After that we examined the fractured surfaces of fractured samples that were close to the deformation limit of fatigue using SEM in order to know their fracture mechanism. We have observed that the corrosive environment caused the fatigue to result in a different mechanism.

International Iron & Steel Symposium
UDCS

Rahma Shaaban Tuğba Akçabaş Hayrettin Ahlatçı Yunus Türen Yavuz Sun Yasin SUBAŞI Ömer Onat Hüseyin Koymatcık

In this study, the effect of gas nitration on the wear behavior of crankshaft was investigated. For this purpose, gas nitration was applied to crankshaft for 12 hours at 500 ° C, and hardness and microstructure images were examined. Nitrided and unnitrided samples were subjected to abrasive wear test under 20N, 40N and 60N load. While 100Cr6 balls were used as abrasive, crankshaft with nitriding and unnitriding was used as counter-material. Nitrided samples have increased wear resistance by about 20% compared to the wear resistance of unnitrided crank shaft samples.

International Iron & Steel Symposium
UDCS

Yusuf Gökalp Yavuz Sun Mehmet Ünal Emre Küçük SAİT ÖZÇELİK Ali Akkuş Burcu Çetintaş Emre Demirci

Heat treatment methods are the most commonly used production steps because they can interfere with all the mechanical properties of the material without altering the chemical composition of the metal in industry. Accelerated cooling is also one of the most prominent points in the series production process in these heat treatment methods. This method is used in the manufacturing process of thin pearlitic steel, double phase steel, rayon sheet steel which is used for bainitic steel production, from construction bar to profile in many different quality and size products. In this study, S355J2 corrugated corrugations and S275JR quality HEA-HEB structural section steels were produced from hot rolled billets produced by open casting method. Intensive inclusions were found in both of the materials examined and it was seen that they could not meet the mechanical strength values in the sizes with low crushing rates. These materials, especially those with low impact strength, have been subjected to accelerated cooling to increase their impact strength.

International Iron & Steel Symposium
UDCS

Fatma KÖZ Furkan ACAR Emre Demirci Hayrettin Ahlatçı Yavuz Sun Yunus Türen Mustafa DEMİRKAZIK Mesut KAYMAZ Şerafettin ÖNER

In this work, the wear resistance behavior of GG-25 gray cast iron was investigated. Three specimens with different austempering time (120, 90 and 60 minutes) and one specimen, which is not austempering, were used. With this manner it has been tried to examine the effect of the parameters of austempering process on each specimen. Pin-on-disc wear resistance test with one loads (20N) on every specimens has been applied according to of ASTM 99 standards. SEM to observe the microstructures characterized the austempered specimens. In addition, brinnel hardness test was applied. With the results of the wear resistance test, as the austempering time increased, wear resistance also increases.

International Iron & Steel Symposium
UDCS

Abdulsamet YILDIRIM Yunus Türen Hayrettin AHLATCI Yavuz Sun Mustafa GUÇLU Hamza Serhat AYDEMIR Mehmet Sami TAKVA

In this study, the effect of C addition on the corrosion behavior of wire rods of 5.5 mm in diameter was investigated. The horizontal and vertical cross sections of the wire rods with 0.7, 0.8, 0.9 C ratio were taken during the metallographical process. The microstructure of the examined specimens was examined by light optical (LOM) and scanning electron microscopy (SEM). Hardness test of steel containing 0.7- 0.9 C was carried out in shimadzu brand micro hardness tester. Corrosion tests of the prepared samples were evaluated according to both the weight loss and the Potentiodynamic Polarization measurements in 3.5% NaCl solution. Despite the increased hardness of the specimens examined, the corrosion resistance decreased. This can be caused by inclusions in the microstructure.

International Iron & Steel Symposium
UDCS

Medine Kilinc Gulheser Dogancik Yunus Türen Yavuz Sun Hayrettin AHLATCI İbrahim AFŞAR Serhat ÖZDEMİR Hüseyin Koymatcık Hüseyin Zengin

In this study, head hardening process was applied for R260 quality rails. Microstructures of rails were carried out using Scanning Electron Microscope (SEM). Hardness distribution of head parts were also evaluated for two category samples (heat treatment and non heat treatment). Wear tests were performed under three different loads (10N, 20N and 40N) in both %3.5NaCI solution and dry conditions. Worn surfaces were characterized by Nikon Shuttlepix, Profile projector and SEM. Results clearly show that, head hardened rails exhibited better wear performance especially under load of 10N in dry conditions.

International Iron & Steel Symposium
UDCS

M. Emre TURAN Fazil Hüsem Yasin Akgül Yavuz Sun Hayrettin Ahlatçı

In this study, the effect of boron addition at different ratios (2-38 ppm) on the microstructure and corrosion properties of Cr-Mo steels was investigated. Square cross-sections of the boron containing steels obtained at different ratios measuring 40×40 mm were rolled in three passes, and a deformation of totally 200-300 percent was obtained. The rolled specimens were examined by optical microscopy and corrosion test. Electrochemical potentiodynamic polarisation measurements were taken to evaluate corrosion behaviours of the examined steels. Analysing the potentiodynamic corrosion test results applied to the CrMo steels containing boron at different ratios, it is seen that there has been increase at the corrosion rates when the boron amounts are low.

International Iron & Steel Symposium
UDCS

Cemal ÇARBOĞA Bülent KURT B. Demirel Yavuz Sun Hayrettin Ahlatçı Engin ÇEVİK

In this study, the effect of carbon content in the range of 0,7-0,9 on wear resistance was investigated. The examined specimens in 5.5 mm diameter are manufactured with drawing process. Wear tests of the cylindrical samples with a length of 20 mm were examined in pin-on-disc type wear tester on counter face of 1.2379 cold work tool steel under the load of 30-60 N. The weight losses of the samples examined increase with the increase of carbon content and hardness. Wear Mechanism is mild wear to oxidative wear.

International Iron & Steel Symposium
UDCS

Semih Gezer Hayrettin Ahlatçı Çağatay Aslan Yunus Türen Yavuz Sun Melike Birinci Meryem Yıldız Neşe ÇAĞLAYAN Hüseyin Koymatcık

- In this study, Cr-W steels were produced by casting then heat treatment was applied for specimens. After the normalization process at 1100 0C for 1 hour, samples were heated up 660 0C and 760 0C to evaluate the effect of tempering temperature. One group of steel were waited at 1 hour and the other group were waited at 2 hours in these temperatures. Hardness of specimens was measured according to the Vickers test method. Wear tests were performed for all specimens under the loads of 10N, 20N and 40N in dry sliding conditions. Microstructure analysis was carried out using Light Optical Microscope (LOM), Scanning Electron Microscope (SEM). Results show that, tempering temperature significantly affects the wear behaviors of samples. These effects can be seen especially under higher loads. And also there is a direct proportion between wear and hardness results

International Iron & Steel Symposium
UDCS

Fatih AYDIN Yavuz Sun MUHAMMET EMRE TURAN Mustafa ACARER Hayrettin Ahlatçı Yunus Türen

In this study, influence of grain size on degree of sensitization and susceptibility to intergranular corrosion of AISI 316 austenitic stainless steel was investigated. As-received AISI 316 austenitic stainless steel samples were first solution heat treated at 1050 oC for 0.5 h, 1.5 h and 3 h in order to obtain different grain sizes and then, each of them was heat treated for sensitization at 700 oC for 1h followed by water quenching. Grain size measurements of the first set of samples were performed by linear intercept method according to ASTM E112 standard and the degree of sensitization was measured by double loop electrochemical potentiodynamic reactivation (DLEPR) test. The results showed that grain size increased as the solution heat treatment time increased. A decrease in the degree of sensitization was observed for the samples having larger grains. That is to say, the increase in grain size improved intergranular corrosion resistance.

International Iron & Steel Symposium
UDCS

Hüseyin Zengin Yunus Türen Hayrettin Ahlatçı Yavuz Sun Burak Dursun Ünsever

In this work we measure and estimate, experimentally and numerically, approximate fatigue strengths of steel filaments of 0.25 mm diameter with 80% C by the pure bending test method. All fatigue tests have been realized at room temperature and at a frequency of 10 Hz via a custom manufactured pure bending tester of which the fully reserved strain value, R = εmin/εmax, is −1. The applied value of cyclic deformation, ε, has been chosen from the range 0.46-1.07. The plots of S-N (Strain–Cycle) curves are based on high fatigue cycle (HFC) lives that are greater than or equal to 106 cycles.

International Iron & Steel Symposium
UDCS

Hüseyin Koymatcık Hayrettin Ahlatçı Yunus Türen Yavuz Sun SAİT ÖZÇELİK

This study aims to determine residual stress distribution in head, web and foot parts of two different quality grooved rails and also to understand effect of carbon content on residual stress in rails. Strain gauges were glued on three regions of specimens and cutting method was applied for residual stress measurement according to the TS EN 13674-1 railway rail standard. Scanning Electron Microscope (SEM) and Optic Microscope (OM) were used for microstructure analysis of regions where the residual stress measurements were performed. Results show that, compressive residual stress is an effective stress type compared to the R260 grade rails. However, R260 grade grooved rails have higher residual stress value than R220 grade grooved rails especially in head parts of specimens.

International Iron & Steel Symposium
UDCS

M. Emre TURAN Yavuz Sun Fazil Hüsem

The aim of this study is to investigate the effect of nitration and nitrox process on wear performances of tool steels. For this purpose, samples were seperated as two categories. One group was exposed to nitration process in salt bath at 530 0C during 6 hours. For other group, nitrox process was applied at 4900C during 2 hours after nitration. Reciprocating wear test was performed for all specimens under the loads of 10N, 20N and 40N according to the ASTM G99 standard. Microstructures and worn surfaces of specimens were analysed using Scanning Electron Microscope (SEM). Results show that, wear performances of specimens exhibit difference when they are exposed nitration and oxidation process. And also they show better performance under the lower loads.

International Iron & Steel Symposium
UDCS

M. Emre TURAN Mustafa ACARER M.Karakus Hayrettin Ahlatçı Yunus Türen Yavuz Sun

Bu çalışmada, patlamalı kaynak tekniği ile üretilmiş alüminyum-çelik-alüminyum tabakalı kompozit numunelerin, plaka yorulma cihazı ile, yorulma davranışı incelenmiştir. Kompozit imalatında, 0.5 mm kalınlığında 1110 kalite çelik ve 1.5 mm kalınlığında 1050 kalite alüminyum saclar kullanılmıştır. Tabakalı kompozitlerle imal edilen plaka parçalar dinamik yüklemelere maruz kaldığı için yorulma davranışının bilinmesi önem arz etmektedir. Tabakalı kompozitler özellikle plaka halde kullanıldığından Şekil 1’de görülen plaka yorulma test numunesi Şekil 2’de verilen plaka yorulma test cihazı ile incelenmiştir.

International Symposium on Light Alloys and Composite Materials
UHAKS

Sakine Obuz Gülcan Çetin Fikri Günsur İlayda Şahin Furkan ACAR Sait Özçelik Mustafa ACARER Süleyman Yaşın Yunus Türen Yavuz Sun Hayrettin Ahlatçı

Bu çalışmada; %0,5 Sn ve %0,5 Pb ilaveli AM60 magnezyum alaşımının mikroyapı ve mekanik özellikleri, optik mikroskop ve çekme testi cihazı kullanılarak incelendi. Döküm işlemi Şekil 1’ deki dört kademeden oluşan 300 °C ye ısıtılmış kademeli kalıp içerisinde yapıldı. Alaşım elementleri hassas terazide tartılarak ayarlandı. Tablo 1’ de alaşımların kimyasal analizleri görülmektedir. Metalografik incelemeleri yapılmak üzere numunelerin yüzeyleri sırası ile 320, 400, 600 ve 800 mesh zımparalar ile saf su kullanılarak zımparalama ve 1μm alümina pasta kullanılarak polisaj keçesinde parlatma işlemine tabi tutuldu ve %75 etilen glikol, %24 saf su, %1 HNO3 karışımı ile dağlandı. Çekme deneyleri için numuneler ASTM E 8M-99 standardına göre hazırlandı. Çekme deneyi uygulaması için ise 5 ton çekme kapasitesine ayarlanabilen çekme cihazında ve 0,5 mm/dk çekme hızında yapıldı. Sertlik deneyi numuneleri çekme çubuğundan 8x5 boyutlarında çıkartıldı ve yüzeyleri zımparalanarak parlatıldı. 1 mm çaplı elmas kare piramit uç ve 50 N yük uygulanarak Vickers cinsinden sertlik değerleri elde edildi.

International Symposium on Light Alloys and Composite Materials
UHAKS

Levent Elen Mehmet Ünal Özcan Büyükgenç Bünyamin ÇİÇEK Ferdi Yıldırım Yavuz Sun Yunus Türen Hayrettin Ahlatçı Erkan Koç

Bu çalışmada; %0,5 Sn ve %0,5 Pb ilaveli AM60 magnezyum alaşımının mikroyapı ve mekanik özellikleri, optik mikroskop ve çekme testi cihazı kullanılarak incelendi. Döküm işlemi Şekil 1’ deki dört kademeden oluşan 300 °C ye ısıtılmış kademeli kalıp içerisinde yapıldı. Alaşım elementleri hassas terazide tartılarak ayarlandı. Tablo 1’ de alaşımların kimyasal analizleri görülmektedir. Metalografik incelemeleri yapılmak üzere numunelerin yüzeyleri sırası ile 320, 400, 600 ve 800 mesh zımparalar ile saf su kullanılarak zımparalama ve 1μm alümina pasta kullanılarak polisaj keçesinde parlatma işlemine tabi tutuldu ve %75 etilen glikol, %24 saf su, %1 HNO3 karışımı ile dağlandı. Çekme deneyleri için numuneler ASTM E 8M-99 standardına göre hazırlandı. Çekme deneyi uygulaması için ise 5 ton çekme kapasitesine ayarlanabilen çekme cihazında ve 0,5 mm/dk çekme hızında yapıldı. Sertlik deneyi numuneleri çekme çubuğundan 8x5 boyutlarında çıkartıldı ve yüzeyleri zımparalanarak parlatıldı. 1 mm çaplı elmas kare piramit uç ve 50 N yük uygulanarak Vickers cinsinden sertlik değerleri elde edildi.

International Symposium on Light Alloys and Composite Materials
UHAKS

Levent Elen Mehmet Ünal Özcan Büyükgenç Bünyamin ÇİÇEK Ferdi Yıldırım Yavuz Sun Yunus Türen Hayrettin Ahlatçı Erkan Koç

Bu çalışmada; %0,5 Sr ve %0,5 TiB ilave edilen magnezyum alaşımının mikroyapı ve mekanik özellikleri, optik mikroskop ve çekme testi cihazı kullanılarak incelendi. Döküm işlemi Şekil 1’ deki dört kademeden oluşan 300 °C ye ısıtılmış kademeli kalıp içerisinde yapıldı. Alaşım elementleri hassas terazide tartılarak ayarlandı. Tablo 1’ de alaşımların kimyasal analizleri görülmektedir. Metalografik incelemeleri yapılmak üzere numunelerin yüzeyleri sırası ile 320, 400, 600 ve 800 mesh zımparalar ile saf su kullanılarak zımparalama ve 1μm alümina pasta kullanılarak polisaj keçesinde parlatma işlemine tabi tutuldu ve %75 etilen glikol, %24 saf su, %1 HNO3 karışımı ile dağlandı. Çekme deneyleri için numuneler ASTM E 8M-99 standardına göre hazırlandı. Çekme deneyi uygulaması için ise 5 ton çekme kapasitesine ayarlanabilen çekme cihazında ve 0,5 mm/dk çekme hızında yapıldı. Sertlik deneyi numuneleri çekme çubuğundan 8x5 boyutlarında çıkartıldı ve yüzeyleri zımparalanarak parlatıldı. 1 mm çaplı elmas kare piramit uç ve 50 N yük uygulanarak Vickers cinsinden sertlik değerleri elde edildi.

International Symposium on Light Alloys and Composite Materials
UHAKS

Levent Elen Yunus Türen Melek YILKI Bünyamin ÇİÇEK Ferdi Yıldırım Yavuz Sun Hayrettin Ahlatçı Mehmet Ünal Erkan Koç

Bu çalışmada; %0,2 ve %1 oranlarında Sb ilave edilen AZ91 magnezyum alaşımının mikroyapı ve mekanik özellikleri, optik mikroskop ve çekme testi cihazı kullanılarak incelendi. Döküm işlemi Şekil 1’ deki dört kademeden oluşan 300 °C ye ısıtılmış kademeli kalıp içerisinde yapıldı. Alaşım elementleri hassas terazide tartılarak ayarlandı. Tablo 1’ de alaşımların kimyasal analizleri görülmektedir. Metalografik incelemeleri yapılmak üzere numunelerin yüzeyleri sırası ile 320, 400, 600 ve 800 mesh zımparalar ile saf su kullanılarak zımparalama ve 1μm alümina pasta kullanılarak polisaj keçesinde parlatma işlemine tabi tutuldu ve %75 etilen glikol, %24 saf su, %1 HNO3 karışımı ile dağlandı. Çekme deneyleri için numuneler ASTM E 8M-99 standardına göre hazırlandı. Çekme deneyi uygulaması için ise 5 ton çekme kapasitesine ayarlanabilen çekme cihazında ve 0,5 mm/dk çekme hızında yapıldı. Sertlik deneyi numuneleri çekme çubuğundan 8x5 boyutlarında çıkartıldı ve yüzeyleri zımparalanarak parlatıldı. 1 mm çaplı elmas kare piramit uç ve 50 N yük uygulanarak Vickers cinsinden sertlik değerleri elde edildi.

International Symposium on Light Alloys and Composite Materials
UHAKS

Levent Elen Yunus Türen Bünyamin ÇİÇEK Yavuz Sun Ferdi Yıldırım Hayrettin Ahlatçı Mehmet Ünal Erkan Koç

Abstract Fiber Metal Laminate (FML) with specific strength and low densities, which is a family of hybrid composite structure formed from the combination of metal layers sandwiching a fiber-reinforced plastic layer, have big potential in aeronautical applications in nowadays [1]. Researchers have tried to fabricate laminated composite materials in order to meet demands of industry. Available literature describes already applied laminates consisting of aluminium alloys and glass fibres (GLARE®), carbon fibres (CARALL®) and aramid fibres (ARALL®) [2]–[4]. Today, materials research is moving towards natural fibre composites/laminates. It is because of factors such as low weight, cost effectiveness, man’s desire to go in for natural products, environment friendliness, renewable nature, biodegradability with respect to fiber, and ready use of plants/trees with less processing [5]. The aim of this study is to investigate of microstructural and mechanical performance of metal laminated composite using both natural fibers and industrial fibers as reinforcement. 1050 H24 Aluminum sheet with 0.25 mm thickness was used as matrix material. Silk fabric and S2-glass fiber were reinforced with aluminum separately. Aluminum sheets were cut to suitable size for hot pressing. Mechanical grinding was applied to improve surface roughness and adhesion mechanism. Metal sheets were washed with distilled water and ethanol, respectively. Then they were waited in the chromic acid solution. Epoxy resin and hardener were weighed (100:20 ratio %wt) and mixed homogenously for lamination process. Two different samples for each reinforced composite were prepared for curing process under heat and pressure in the hot-pressing device according to the metal-fiber-metal- fiber-metal stacking sequence (Figure 1) by hand lay-up. The prepared laminate composites were cured at 80 °C and under 1 ton pressure for three hours. Microstructures of laminate composites were characterized using Scanning Electron Microscope (SEM). Samples were prepared for tensile test to examine mechanical properties. Results show that good adhesive bonding was achieved and there were no macro defects such as porosities in microstructure for all specimens. Composites exhibited different mechanical performance (Table 1) and S-2 glass fiber reinforced composite showed best mechanical properties among the specimens. But when the adhesion mechanism of the silk fabric to the resin is improved, it can be used as an alternative natural reinforcement for fiber metal laminates.

International Symposium on Light Alloys and Composite Materials
UHAKS

Mustafa Yunus ASKIN Yunus Türen MUHAMMET EMRE TURAN Yavuz Sun Hayrettin Ahlatçı

Zinc (Zn) has been widely used as main alloying element in magnesium alloys. Zn improves corrosion resistance and strength of magnesium alloys by grain boundary strengthening, solid solution and precipitation hardenings [1,2]. Zn has 6.2 wt% maximum solid solubility in Mg and together with Mg can form binary coherent compounds [3].

International Symposium on Light Alloys and Composite Materials
UHAKS

Hüseyin Zengin Yunus Türen Hayrettin Ahlatçı Yavuz Sun Emre Öztürk

In the study, the AZ31 and AZ31+ La%0.2 Mg alloys were produced by low pressure casting method following homogenization at 400°C for 24 hours and the hot rolling process applied with 15% deformation rate per pass at 400°C. The surface treatment process of shot peening was practised on materials for enhancement corrosion properties of them. To observe corrosion behaviour of investigated alloys the immersion corrosion test in %3.5 NaCl environment and metallographic examination were utilized.

International Symposium on Light Alloys and Composite Materials
UHAKS

Soner Arı İsmail Hakkı Kara Medine Kılıç Yaren Karauğuz Okan Ünal Yunus Türen Yavuz Sun Süleyman Yaşın Batuhan Özusta Hayrettin Ahlatçı

In the study, the AZ31 and AZ31+ La%0.5 Mg alloys were produced by low pressure casting method following homogenization at 400°C for 24 hours and the hot rolling process applied with 15% deformation rate per pass at 400°C. The surface treatment process of shot peening was practised on materials for enhancement mechanical properties of them. The surface roughness of AZ31 and AZ31+ La%0.5 Mg alloys how is developed by shot peening process also was determined.

International Symposium on Light Alloys and Composite Materials
UHAKS

Nihal Kanca İsmail Hakkı Kara Özlem Keleş Canan Dursun Okan Ünal Yunus Türen Yavuz Sun Hayrettin Ahlatçı Süleyman Yaşın

Abstract In this study, AZ31 and AZ31+1.0La wt% alloys were produced by a low pressure die casting method. The rolling capability of these alloys was investigated at different rolling parameters such as speeds and deformation rates. Macro images of sheets were utilized to observe effects of amount La on rolling capability and light optical microscopy, were employed to characterize the microstructure of the alloys. It was observed that crack formation usually was occurred on lower rolling speeds and higher deformation rates.

International Symposium on Light Alloys and Composite Materials
UHAKS

İsmail Hakkı Kara Hayrettin Ahlatçı Yunus Türen Yavuz Sun Mehmet Ünal

Magnesium have an enormous potential for automobile and aerospace industries due to its low density, high specific strength and good damping ability [1]. However, the low wear resistance and low mechanical properties of Mg hinder the use of Mg in industrial applications [2]. To improve these low properties of Mg, Mg metal matrix composites are widely produced with different reinforcements such as SiC [3], B4C [4], Al2O3 [5]. TiC is a reinforcement material with high hardness and extreme wear resistance [6]. However, the investigation of the effect of TiC on mechanical and wear properties is quite limited.

International Symposium on Light Alloys and Composite Materials
UHAKS

Fatih AYDIN Yavuz Sun MUHAMMET EMRE TURAN Hayrettin Ahlatçı Yunus Türen Mustafa ACARER

Magnesium alloys have great potential in aerospace, automotive and electronic industries due to high specific strength and low densities [1], [2]. Because high specific strength and lightweight materials are needed to improve energy efficiency [3],[4]. However, magnesium alloys have poor mechanical properties, so this situation limits the usage of magnesium in practical applications. There have been a lot of attempts by researchers to overcome deficiencies of magnesium alloys, especially for decades. Researchers develop mechanical properties of magnesium by incorporating reinforcement materials. Micron size reinforcements are generally preferred but nowadays, nano-size materials especially carbon based are becoming popular subject for researchers. In this study, graphene nanoplatelets (GNPs) which is an allotrope of carbon is used as a reinforcement material for magnesium matrix composite. Aluminum was also used to evaluate its binding effects on Mg-GNPs composite. Pure Mg, Mg-0.25 wt.% GNPs, Mg-3Al-0.25 wt.% GNPs and Mg- 9Al-0.25 wt.% GNPs composites were fabricated using semi powder metallurgy technique. GNPs was exposed to ultrasonication process in ethanol for an hour in order to break Vander Waals bonding between carbon atoms. Mg-Al powder (mixed in Turbula mixer for two hours) was added to GNPs/Ethanol solution. Powders were mixed using magnetic stirrer which is connected to the vacuum distillation system. Process was continued until the ethanol removed from the system. Then obtained powder was dried in vacuum drying oven. Dried powders were compacted in graphite mold under 50 MPa applied load in hot pressing device. Argon was used to prevent oxidation and pressing, and sintering temperatures were chosen as 550 ºC. Experimental densities were calculated by Archimedes technique. Microstructures of produced samples were characterized using X-ray diffraction and Scanning Electron Microscope (SEM). Hardness test was applied according to the Vickers test method. Compression tests were performed for all samples to investigate mechanical effects of aluminum and GNPs on magnesium-based composite. Results show that uniform distribution of carbon atoms is seen for GNPs reinforced composites. Figure 1 shows SEM images of Mg-3Al-GNPs and Mg-9Al-GNPs composites. Microstructures are free of macro porosities. As shown in Table 1, hardness of pure magnesium is significantly improved with the addition of Aluminum and GNPs. It can be concluded that reinforcement materials may restrict the dislocation motion and aluminum can exhibit lubricant effect between matrix and GNPs. Compression tests reveal that 0.2% Compression Yield Strength (CYS) and Ultimate Compression Strength (UCS) are enhanced with the addition of reinforcement. Thus, mechanical properties of pure magnesium were significantly improved even low content of carbonaceous reinforcement.

International Symposium on Light Alloys and Composite Materials
UHAKS

MUHAMMET EMRE TURAN Yavuz Sun Fatih AYDIN Hüseyin Zengin Yunus Türen Hayrettin Ahlatçı

Abstract Rare earth (RE) additions can improve mechanical properties at room and elevated temperatures, formability and castability of magnesium alloys [1-3]. Recently, numerous studies have been conducted about wrought Mg-Zn-Zr- RE alloys due to their excellent strength and great potential for further development. In this study, microstructure, mechanical and corrosion properties of as-cast and as-extruded Mg-6Zn-0.5Zr (wt%) alloy, also denoted as ZK60, with minor La addition were investigated. Mg-6Zn-0.5Zr-0.2La magnesium alloy was produced by low-pressure die casting method under a protective argon gas atmosphere. Pure Mg (99.9%) ingots were melted at 750 °C and pure Zn (99.7%), Mg-30 wt% Zr and Mg- 30 wt% La master alloys were added into the molten Mg. The melt was held at this temperature for 30 min and stirred for 15 min to ensure a full dissolution of alloying elements. After applying a pressure of 2 bar into the air tight electric resistance furnace, the melt was transferred from the crucible to the steel mould preheated to 250 °C through the rising steel tube and cylindrical ingots with a diameter of 34 mm and length of 190 mm were obtained. After casting, the as-cast alloys were homogenized at 400 °C for 24 h and water quenched. Then, each homogenized billet was machined into cylindrical bar with a diameter of 32 mm and length of 30 mm. For extrusion process, the machined billets and the extrusion die were preheated to the target temperature for 40 min and directly extruded at an initial temperature of 300 °C with an extrusion ratio of 16:1 and a ram speed of 0.3 mm.s-1. Microstructure characterizations were conducted by a Nikon optical microscope (OM) and a Carl Zeiss Ultra Plus field emission scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). The constituent phases in the as-cast alloy and the macro-texture of the extruded alloy were characterized by X-ray diffraction (XRD-Rigaku Ultima IV). Tensile tests were conducted on a Zwick/Roell Z600 universal testing machine at a strain rate of 1.67 x 10-3 s-1 at room temperature (RT). The samples for immersion corrosion test (Φ 5 mm x 15 mm) were cut from the half radius of the alloys, followed by grinding and polishing. Then, the samples were immersed in 3.5 wt% NaCl solution at room temperature for 72 h. The electrochemical corrosion tests of the alloys were also performed in 3.5 wt% NaCl solution at room temperature by a Gamry model PC4/300 mA potentiostat/galvanostat with DC105 corrosion analysis.

International Symposium on Light Alloys and Composite Materials
UHAKS

Hüseyin Zengin Yunus Türen MUHAMMET EMRE TURAN Hayrettin Ahlatçı Yavuz Sun

Bu çalışma kapsamında 1075 ve 15N20 kalite çeliklerinden patern kaynağı yöntemiyle imal edilmiş olan damascus çeliğinin mikroyapı analizleri, vickers sertlik değerleri, darbe-çentik enerjisi değerleri ve standartlarca hazırlanan numunelerle(Şekil.1) yapılan yorulma deneyinden elde edilen sonsuz yorulma ömrü ve wöhler eğrisi belirlenmiştir. İncelenen damascus çeliği korozyon dayanımları ve mekanik özellikleri birbirinden farklı olan 1075 ve 15N20 kalite çeliklerinden patern kaynağı yöntemiyle imal edildiğinden dolayı tabakalı çelik-çelik kompozit bir yapıya sahiptir.[1-8] Yüksek mukavemetli çeliklerin alternatifi düşünülebilecek damascus çeliğinin hareli(tabakalı) yapısının dinamik yükler karşısında sergileyeceği yorulma davranışının belirlenmesi amacıyla plaka yorulma deneyi şuana kadar başka bir çalışmada yapılmamıştır.

International Symposium on Light Alloys and Composite Materials
UHAKS

Furkan ACAR Fatma KÖZ Hakan KIRDAN SAİT ÖZÇELİK Yavuz Sun Yunus Türen Süleyman Yaşın Emre Demirci Hayrettin Ahlatçı

Raylar demiryolu alt yapısının en önemli parçasıdır. Demiryolu altyapısında kullanılan raylarda üzerinden geçen yük esnasında meydana gelen gerilmelerin bilinmesi, mekanik özelliklerini ve kullanım ömürlerini tahmin etme hususunda önemli bilgiler vermektedir. Bu çalışmada, demir yolu hattına döşenmiş R260 kalite ve mantarı sertleştirilmiş R350 HT kalite raylarda gerilme ölçümleri yapılmıştır. Gerilme ölçümlerinde özel elektriksel dirence sahip bir aparat olan gerinim ölçerler (strain gauge) kullanılmış ve ölçümler hem düz yolda hem de virajlı kurplarda yapılarak kıyaslamalar yapılmıştır. Sonuçlar değerlendirildiğinde, mantarı sertleştirilmiş raylarda üzerinden yükü ve hızı bilinen vagonlar geçtiğinde meydana gelen gerilim değerleri normal raylara göre daha düşük çıkmıştır. Aradan iki aylık bir süre geçtikten sonra ölçümler tekrarlandığında herhangi bir mekanik hasarın olmadığı benzer gerilme değerlerinin çıkmasıyla anlaşılmıştır. Rails are the most important part of the railway infrastructure. Knowing the stresses that occur during the load passing on the rails used in railway infrastructure gives important information about the estimation of mechanical properties and service life. In this study, strain of R260 quality and head hardened R350 HT quality rails on the rail lines was measured. Strain gauges, which have special electrical resistance, were used in the stress measurements and the measurements were made on both straight and curved curves. When the results were evaluated, the tension values on the head hardened rails were lower than the normal rails when the wagons (the load and speed are known) were passed. After two months, the measurements were repeated, and similar stress values were obtained without any mechanical damage.

International Symposium on Railway System Engineering
ISERSE

MUHAMMET EMRE TURAN Yavuz Sun Hayrettin Ahlatçı SAİT ÖZÇELİK

Ulaşım sektörü, her yönüyle, ülkerin refah düzeyi için belirleyici bir parametredir. Özellikle sanayi ürünlerinin, nakliyesinin kolaylığı ve nakliye maliyetlerinin düşük olması önemlidir. Demiryolu ulaşımı bu noktada kolay, ucuz ve güvenli bir çözümdür. Tabiki bu çözümü uygulayabilmek için de yeterli demiryolu ağı ve altyapıya sahip olmak gereklidir. Bu ihtiyaca binaen, ülkemizde demiryolu sektörüne büyük yatırımlar yapılmaktadır. Demiryollarındaki gelişmelerle beraber ortaya çıkan daha kaliteli malzeme ihtiyaçları ve bu malzemelerin maliyetleri, ihtiyacın yerli kaynaklarla karşılanması fikrini ortaya çıkarmaktadır. Bu bağlamda ülkemizin daha önceden kullanmadığı ya da ithal ederek kullandığı uzun ömürlü rayların yerli kaynaklarla imal edilmesi projelendirilmiş ve TÜBİTAK desteği ile başarılı bir şekilde üretilmiştir. Bu çalışmada, Kardemir A.Ş., Karabük Üniverstesi ve DATEM işbirliği ile, ülkemizde ilk kez EN 13674 standardına göre R350HT kalite mantarı sertleştirilmiş (uzun ömürlü) raylar üretilmiştir. Saha kondüsyonları ve aşınma profilleri incelenmiş, laboratuvar ve servis şartlarındaki başarıları ortaya konulmuştur. The transport sector is a decisive parameter for the welfare of the country in all aspects. Particularly, it is important that the transportation of industrial products, ease of transportation and low transportation costs. Railway transportation is easy, cheap and safe at this point. Of course, it is necessary to have adequate rail network and infrastructure to implement this solution. With this need, large investments are made in the railway sector in our country. The need for higher quality materials and the costs of these materials together with the developments in the railroads brings up the idea of meeting the need with domestic resources. In this context, our country has previously imported or not used to be manufactured with domestic resources long-life rails have been designed and successfully produced with the support of TUBITAK. In this study, the condition and wear profiles of the rugged rails of the R350HT quality mushroom hardened (long life) produced in accordance with the EN 13674 standard were investigated in cooperation with Kardemir AS, Karabük University and DATEM. In this study, in accordance with EN 13674, R350HT quality head hardened (long life) rails were produced for the first time in Turkey in cooperation with Kardemir AS, Karabük University and DATEM. Field conditions and wear profiles were examined and their success in laboratory and service conditions were determined.

International Symposium on Railway System Engineering
ISERSE

Hayrettin Ahlatçı Yavuz Sun İsmail Esen MUHAMMET EMRE TURAN SAİT ÖZÇELİK İBRAHİM TOZLU

In this work, Brinell hardness test, impact test, bend test results of four different types of honeycomb composite materials, which are important for todays in the Civil Aviation Sector and which have been undergoing significant improvements over the past 20 years, have been investigated. The thickness of the mechanical properties of the composites differed with the length of the part and the chemical resin used. The white material in 1,2 cm thickness is used in side and ceiling in cargo area. The light yellow materials is 1,2 cm thickness and is used on the cargo floor and on the wet and dry floors of Airbus, Boeing branded aircraft. Black materials (on wet floors) material in 9,9 cm thickness and used in Passenger Glasses. Yellow Color resinized honeycomb composite in lyophilized form is 1cm thick and used on the bottom of cargo section. Hardness measurements were carried out with a 2.5 mm ball and a load of 187.5 kg under the Brinell Hardness Tester . When the hardness results were examined, when the white composite was damaged, the highest hardness value was found as yellow composite (54,92 HB) value of black composite (26.02 HB). The open saddle stiffness is 31,43 HB.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

Muharrem Ilbeyi Incedere Emre Yildirim Emre Demirci Batuhan Ozusta Hayrettin AHLATCI Yavuz Sun Yunus Türen SAİT ÖZÇELİK Fazil Hüsem

In this study, the effect of homogenization heat treatment on the corrosion behaviour and mechanical properties of Co-Cr (Dental), Co-Cr (Denture) and Ni-Cr (Dental) based casting materials used as dental implant materials was investigated. Samples prepared as 7 mm in diameter x 10 mm cylindrical in a special silicon-graphite-containing powder mixture for preventing oxidation were annealed at different times in the range from 0.5 to 3 hours at 1000 ° C. Microstructural investigations of the samples heat treated and casted was performed on longitudinal and circular sections by Leica DM ILM model optical light microscope and then hardness measurements were carried out with Brinell hardness tester with 2,5 mm ball and 187,5 kg load. The corrosion behaviour of the Co-Cr and Ni-Cr based materials formed in the optimum parameters, which show improvement in the final mechanical properties of microstructure and hardness measurement data, compared with cast materials, was studied by potentiodynamic polarization test in Hanks liquid. The corrosion damage mechanism was determined by scanning electron microscopy. The icorr and Ecorr values of the heat-treated materials evaluated after the corrosion made by the potentiodynamic polarization test method has been increased with respect to that of the casted materials.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

Medine Kilinc Batuhan Ozusta Gulheser Dogancik Canan Dursun Hayrettin AHLATCI Yunus Türen Yavuz Sun Alperen R.B. ÖZSARI

In this study, the wear behavior of hot rolled AZ31 and AZ31-X wt% La Mg alloys were investigated. After the microstructure characterization, hardness and wear tests, the effect of La on the wear resistance of AZ31 Mg alloy were reported. Hot Rolling process introduced the twins and DRXs on the microstucture wherein the changing of grain boundaries density impart wear resistance to AZ31 Mg alloy.

International Conference of Advanced Materials and Manufacturing Technologies
ICAMT

İsmail Hakkı Kara Hayrettin Ahlatçı Yunus Türen Yavuz Sun Harun ÇUĞ Mehmet Ünal

Yorulma mukavemeti, günümüzde kullanılan tüm malzemeler için önemli bir kriter haline gelmiştir. İlk başlarda malzemelerin statik olarak taşıdıkları yükleri servis şartlarında taşıyamadıkları göze çapmıştır. Bu durum “çevrimli yükleme” olgusunun literatüre girmesine sebep olmuştur. Çevrimli yüklemeler, malzemenin yüzeyinde bir çatlak oluşturarak ya da mevcut bir süreksizlikten faydalanarak hasara sebep olurlar. Yorulma mukavemetinin belirlenmesinde bir çok test yöntemi ve cihaz mevcuttur. Bunların tamamı belirli bir yükün, farklı şekillerde, tekrarı esasına dayanmaktadır. Uygulanan testler arasında en az maliyetli ve en basit olan yöntem dönel eğmeli yorulma testidir. Bu çalışma kapsamında muhtelif araştırmalarda kullanılmak üzere R.R. Moore tipi bir yorulma test cihazının tasarımı ve mevcut imkanlarla imali anlatılmaktadır. Cihaz 1.5hp gücünde bir motorla dönme hareketini gerçekleştirebilmekte ve maksimum 5000 devir/dakika hıza ulaşabilmektedir. Cihaz üzerinde bulunan sürücü ile hız ayarlamaları da yapılabilmektedir. Numunenin çevrim sayısı ise cihaz üzerindeki elektronik sayaç vasıtasıyla kaydedilmektedir. Farklı boylarda numunelerin bağlanabilmesi için lineer kızak sistemi ve parça kırıldığında cihazı otomatik olarak durdurabilecek bir mekanizma mevcuttur. R.R. Moore tipi yorulma test cihazında var olan terazi tipi yükleme sistemlerinin aksine bu cihazda yük hücresi kullanılarak daha hızlı ve doğruluk oranı daha yüksek testler yapılabilmektedir. Fatigue strength used nowadays for all materials has become an important criterion. At first, materials, they carry the static applied loads, were observed to withstand these loads in service conditions. In this case concept of "loading cycle" has led to the introduction into the literature. Cyclic loading can cause damage by creating fracture on the surface of the materials or benefiting from an existing discontinuities. There are many machine and method for determining the fatigue strength. All of them is based on repetition of a load in different ways. Rotating bar bending test among the tests used is low cost and most simple method. In this study, design and manufacturing of R. R. Moore type fatigue test device used in various studies are described with existing facilities. The device can perform rotational motion by A motor with 1.5 hp and can reache a speed of maximum of 5000 rev / min. Speed adjustment can be made with the drive on the device. The number of cycles is recorded simple by electronic meters on the device. Linear slide system has been established to test sample of different sizes on the device. In addition, a mechanism automatically stopped when specimen broken is available on the device. In the designed device more accurate and faster tests can be done using load cell in contrast to existing scale type loading system in R. R. Moore-type fatigue testing devices.

International Symposium on Industrial Design Engineering
ISIDE14

Emre KÜÇÜK SAİT ÖZÇELİK Kerem Ali BAKACAK Yavuz Sun Hayrettin Ahlatçı

Aşınma sürtünen yüzeylerde malzeme kaybı olarak tanımlanır. Aşınmayı tamamen önlemek ise olanaksızdır. Aşınma büyük ekonomik kayıplara neden olduğundan üzerinde yoğun araştırmalar yapılmaktadır. Malzemelerin aşınma mekanizmaları, adhesiv, abrasiv, erozif ve korozyonlu aşınma şeklindedir. Her bir aşınma testi farklı cihazlar yardımı ile yapılabilmektedir. Bu çalışmada bu aşınma mekanizmalarının hepsinin birden test edilebiliceği tek bir cihazın tasarımı ve imalatı yapılmıştır. Tasarlanan aşınma cihazında 2.2 KW’lık, 1450 d/dk’lık ve 0.25 KW’lık 915 dev/daklık üç faz ile çalışan alternatif akım motorları, 2.2 ve 0.4 KW’lık inverterler, hareketin otomatik olarak sonlandırması için spiral plastik yay tahrikli limit switch, karşı malzeme olarak dolu halka blok, aşındırıcı kaplı tambur kullanılmıştır. Wear is defined as the loss of materials at the rubbing surfaces It is impossible to completely prevent wear. Wear causes huge economic losses so intensive research is being conducted in Wear. Wear mechanisms of materials are adhesive, abrasive, erosive and corrosive wear shape. Each abrasion test can be performed with the aid of different devices. All of the wear mechanism in this study may be tested once the design and manufacture of a single device is made. In this study, three-phase alternating current motors working at 2.2 KW-1450 rev/min and 0.25 KW-915 rev/min, inverters with 2.2-0.4 KW, spiral plastic spring actuated limit switches for wear process automatically terminated, abrasives coated drum and metal block as counter device is used.

International Symposium on Industrial Design Engineering
ISIDE14

Öznur ŞİŞMAN Onur ÖZER Ahmet KELEŞ Yiğit GÜMÜŞBOĞA Emre TABAN Yavuz Sun Hayrettin AHLATCI