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Characterisation and comparison of disc brake pads of heavy vehicles by experimental methods
(Inderscience Enterprises Ltd, 2019) Topuz, Polat; Comert, Zekeriya Yasar; Topuz, Ahmet
In this study, characteristics of disc brake pads of heavy vehicles produced by three different manufacturers were compared experimentally. The former pad is the original (OEM), the latter pad is the subsidiary industrial production (SIPM), and the third pad is the Turkish production (TM). These brake pads which have different compositions; components, wear and friction characteristics, mechanical and physical properties were investigated and also the environment and usage were compared among each other. For chemical analysis, energy distribution spectroscopy (EDS) system integrated with scanning electron microscope (SEM) and X-ray fluorescence (XRF) device were used. Thermal gravimetric (TG) analysis was performed to determine the mass losses in the pad materials. Wear friction tests of pads were made according to JIS D 4411 standard. Apart from these, the hardness, density and internal shear strength values of the pads are measured.
Effect of hot dip galvanized coating on the corrosion resistance of the external surface of reinforcement steel
(Carl Hanser Verlag, 2016) Aydin, Ozlem; Topuz, Polat
Studies have been carried out to investigate the performance of hot dip galvanized coating on reinforcement corrosion. The coated and uncoated concrete specimens were subjected to accelerated corrosion to determine the time to corrosion initiation. The accelerated corrosion test results clearly showed that the specimens with hot dip galvanized coatings performed very well against reinforcement corrosion and were better than uncoated specimens.
Effect of laser welding speed on pore formation in AA 6061 T6 alloy
(Carl Hanser Verlag, 2020) Is, Emine Gundogdu; Topuz, Polat; Akman, Erhan; Yilmaz, Muharrem
In this study, 6 mm thick plates of Al 6061 T6 alloy are joined by laser welding at four welding speeds (40 mm x s(-1), 35 mm x s(-1), 25 mm x s(-1), and 20 mm x s(-1)). The welded joints are made using a 4000 W fiber laser welding machine. The effect of laser welding speed on the pores formed in the weld seam was investigated. In this manner, it was found that with a change in laser welding speed the amount of pores formed in the structure also changed. In addition, after the welding process, macroscopic examinations, tensile tests and the hardness tests were made. As a result of the experiments performed, it was determined that, the laser welding speed was highly effective for pore formation.
Effect of PWHT on Mechanical Properties of High Temperature and Pressure Resistant Nuclear Power Plant Steel Welded with SMAW and GTAW Methods
(2019) Topuz, Polat
This research aims at effect of Post Welding Heat Treatment (PWHT) on mechanical properties of 2.25Cr1Mo (P22) high temperature and pressure resistant nuclear power plant steel welded with GTAW (gas tungsten arc welding) and SMAW (shielded metal arc welding). Pre-heating was applied to the materials to be welded at 200°C before welding processes. Welding processes of materials were performed at room temperature. After welding processes, post weld heat treatment (PWHT) was applied at 750?C for 2 hours. Before and after the PWHT, welded materials were prepared in accordance with EN standards for tensile, bending, impact, hardness tests and macrostructure examinations for the investigation of mechanical properties.
Effect of TIG welding parameters in joining grade 2 pure titanium
(Walter De Gruyter Gmbh, 2021) Sonmez, Murat; Topuz, Polat
Grade 2, the most widely used pure titanium in the industry, has high corrosion resistance, excellent ductility, good weldability and is easily machinable. If titanium is exposed to temperatures above 500 degrees C due to moisture or hydrocarbons in the air, it is susceptible to taking up oxygen, nitrogen, carbon and hydrogen. This can cause cracks, especially after welding. Therefore, protection of the welding zone from external factors is of great importance during welding. For these reasons, TIG welding is the most widely used method for titanium welding. In this study, Grade 2 pure titanium plates are joined by TIG welding at three (40 A, 60 A and 80 A) current values under the same conditions. For the welding process, 2 wt.-% cerium addition Tungsten tip and high purity (99.99 vol.-%) argon was used as a shielding gas. After a visual inspection of the welded samples, microstructure inspections, macrostructure inspections, hardness measurements, bending tests and tensile tests were performed in accordance with the standards. As a result of the investigations, it was determined that the most suitable current value for the joining of Grade 2 titanium by TIG welding was 60 A.
Effects of different profiled pins used in friction stir welding of Al 6061 T6
(Walter De Gruyter Gmbh, 2023) Is, Emine Gundogdu; Kocak, Kadir; Basar, Zeynep Sueda; Yavuz, Yagizer; Topuz, Polat
In this study, Al 6061 T6 alloy was joined by friction stir welding method with the same parameters using with different profiled pins. As a result of the experiments carried out, the samples were subjected to metallographic examination, hardness measurements, tensile test and bending test. As a result of the examinations carried out, changes in welding performances were determined with the change of pin profiles. As a result of these changes, it was determined that the pin profile suitable for the applied welding parameters was pyramid. It has been concluded that in the use of triangular profile pins, the welding parameters in question should be higher, and the most important reason for this is that the stir zone is larger.
Experimental characterization and comparison of automobile brake linings
(Carl Hanser Verlag, 2019) Topuz, Polat
In this study, characteristics of automobile disc brake linings produced by three different manufacturers were compared experimentally, these being original parts (OEM), subsidiary industrial production parts (SIPM), and brake linings of Turkish production (TM). These brake linings which vary in composition, components, wear and friction characteristics, as well as mechanical and physical properties were investigated. In addition, their environment and their usage were compared. For the ensuant chemical analyses, scanning electron microscopy (SEM), EDS (energy dispersive spectroscopy) system and XRF (X-ray fluorescence) were used. TG (thermo gravimetric analysis) was performed to determine the mass losses in the brake lining materials. Wear friction tests of the brake linings carried out according to the JIS D 4411 standard. Apart from these, the hardness, density and internal shear strength values of the brake linings were measured.
INVESTIGATION OF WEAR BEHAVIOR OF BORONIZED AISI 316 STAINLESS STEEL
(2019) Topuz, Polat; Aydoğmuş, Tuna
In this study, the wear behavior of boronized AISI 316 stainless steel was investigated. The chemical analysis ofthe sample to be used in the experiment was carried out with optical emission spectrometry before starting theboronizing experiment. Boronizing experiment using pack-boronizing method were carried out at 950°C for 3hours. As the boron source, a powder mixture having the commercial name Ekabor 2 consisting of SiC, B4C andKBF4, was used. As a result of the boronizing treatment, the boride layer formed on the surface of AISI 316,morphologically by Scanning Electron Microscope (SEM-BEI), thickness by optical microscope integrated visualanalyze system, hardness by Vickers indenter and chemical analysis by XRD (X-ray diffraction) device, wereinvestigated. Then, friction tests were carried out to determine the wear resistance of the boride layer. As a result,it is determined that the boron layer formed on the surface of boronized AISI 316 stainless steel, consists of adouble phase iron-boride layer. This layer is a columnar morphology and homogeneous thickness. Also it hasbeen determined to have ultra-hard and high wear resistance.
Kinetic characterization of boride layers formed on AISI 316 stainless steel
(Carl Hanser Verlag, 2020) Aydin, Ozlem; Topuz, Polat; Aydgomus, Tuna
This paper presents the growth kinetics of the boride layer formed on a boronized AISI 316 (X5CrNiMo17-12-2) stainless steel surface. Samples were boronized applying the Ekabor 2 (TM) boronizing agent in an atmosphere controlled furnace at 1073, 1173 and 1273 K for 1, 2 and 3 h by the powder pack method. Surfaces of the samples which have completed the boronizing process were prepared for metallographic examinations. An optical microscope and an integrated image analyzer were used to measure the thickness of the boride layer formed on the surface of the samples. Due to the dual phase structure of the boride layer formed on the steels in order to see these phases in detail, an SEM (Scanning Electron Microscope) image of the sample was taken with the help of the back scattered electrons. In addition, for determination of the elements constituting these phases, elemental analysis was carried out with the help of an EDS (Energy Dispersive Spectroscopy) unit connected to SEM. Then XRD (Xray diffraction analysis) analyses were carried out to understand in detail which phases formed the boron layer. For hardness measurements of boride layers, a Vickers hardness device with 100 g weight was used. Finally, to determine the growth kinetics of the boronized samples, calculations were made with the help of the Arhenius equation and compared with the literature.
Kinetic Investigations of Boronized Cold Work Tool Steels
(Carl Hanser Verlag, 2014) Topuz, Polat; Yilmaz, Eren; Gundogdu, Emine
In this study, kinetic examinations on boronized X45NiCrMo4 (DIN 1.2767) and 90MnCrV8 (DIN 1.2842) steel samples are described. Samples were boronized in indirect heated fluidized bed furnace at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h. Morphologically and typically examinations of borides formed on the surface of the steel samples were studied by optical microscope, scanning electron microscope (SEM), and X-ray diffraction (XRD). Boride layer thickness formed on the steel X45NiCrMo4 ranges from 45 mu m to 382 mu m and for the material 90MnCrV8 ranges from 33 mu m to 471 mu m. The hardness of the boride layer formed on the steel X45NiCrMo4 varied between 1713 HV0.1 and 2111 HV0.1 and for the steel 90MnCrV8 between 1716 HV0.1 and 2761 HV0.1. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as a function of boronizing time and temperature. The kinetics of the reaction has been determined with K = K-o exp (-Ct/RT) equation. Activation energy (G) of the bonded steel X45NiCrMo4 was determined as 156 kJ/mol and that of the steel 90MnCrV8 was determined as 179 kJ/mol.
Microstructure of a chrome-boriding of induction hardened DIN Ck 45 steel
(Walter De Gruyter Gmbh, 2022) Topuz, Polat
In this study, boriding of DIN Ck 45 steel, which is hard chrome plated after induction hardening, is used as a linear shaft in 3D printers. The boriding treatment, which was carried out by the pack-boriding method, was carried out in an atmosphere-controlled furnace at 1273 K for 2 h. The thickness, morphology, hardness, and chemical composition of the boride layer formed on the sample surface as a result of the boriding process using Ekabor 2 boriding agent were examined and compared with the un-borided sample. The microstructure images were obtained with a digital camera integrated into an optical microscope, and these images were analyzed in detail with the help of an image analysis program. After the optical microscope examinations were completed, point EDX analyzes were performed on the image obtained with the help of SEM. As a result of EDX analysis, it was determined that the layer formed on the material surface was only chromium boride formed by the interaction of chromium and boron element. Finally, the hardness measurements of the borided sample were carried out with the help of Vickers indenter and then differences were compared with the un-borided sample.
Otomobil Disk Fren Balatalarının Deneysel Yöntemlerle Karakterizasyonu ve Karşılaştırılması
(2018) Topuz, Ahmet; Topuz, Polat
Bu çalışmada ülkemizde kullanılan otomobillere ait yerli ve yabancı olmak üzere 3 adet fren disk balatasının bileşenleri; aşınma-sürtünme karakteristikleri, mekanik ve fiziksel özellikleri açısından deneysel çalışmalarla incelenmiş, yerli, yabancı ve orijinal (OEM) olanların birbirleri ile çevre ve kullanım açısından karşılaştırılmaları yapılmıştır. Kimyasal analizlerde, tarama elektron mikroskobu EDS (enerji dağılımlı X-ışını analizi) sistemi ve XRF (X-ışını floresans spektrometresi) kullanılmıştır. Balata malzemelerinin sıcaktaki kütle kayıplarını belirlemek için TG (Termo Gravimetrik) analizleri yapılmıştır. Ayrıca ısısal değişiklikleri tespit amacıyla DT (Diferansiyel Termal) analizleri gerçekleştirilmiştir. Balataların aşınma sürtünme testleri JIS 4411 standardına göre yapılmıştır. Bunların dışında balataların sertlik, yoğunluk, iç kesme dayanım değerleri ölçülmüştür. Deneysel veriler yabancı ve yerli balatalar için çevre ve kullanım açısından karşılaştırılmıştır.
Simulation of boronizing kinetics of AISI 316 steel with an integral diffusion model
(Walter De Gruyter Gmbh, 2021) Keddam, Mourad; Topuz, Polat; Aydin, Ozlem
Boriding or boronizing is a type of surface property improvement process applied to metal or some non-metal materials by diffusion. The calculation of diffusion kinetics is also very important as it is a diffusion controlled process. Today, many researchers perform kinetic calculations by applying the Second Fick's law to the Arrhenius equation. In this study, as an alternative to conventional kinetic calculations, the mathematical modeling of diffusion kinetics has been performed using the integral diffusion model. For the boronizing experiments, the pack-boronizing method was chosen and AISI 316 austenitic stainless steel was used. The experiments were carried out at three temperatures and for three times; Ekabor 2 was used as the boronizing agent. The detailed diffusion kinetics calculations were made using the data obtained from the experiments in the mathematical modeling.
Single Boride Layer (Fe2B) Formation of Borided AISI M2 High-Speed Steel
(2023) Aydoğmuş, Tuna; Çiçek, Bünyamin; Topuz, Polat; Aydın, Özlem
In this study, the boriding process of AISI M2, which is in the high-speed steel class, was carried out with the pack-boriding method. Samples of 20x20x15 mm were borided in an atmosphere-controlled furnace at 900, 1000, and 1100°C for 2,4, and 6 hours. For the boriding heat treatment, AISI 316 stainless steel crucible and a powder mixture with the trade name EKABOR 2 as boa riding agent were used. After the boriding process was completed, the samples were prepared for the metallographic study. Scanning electron microscope (SEM) with the help of backscattered electrons (BE) was used for microstructure investigations, and EDX (Energy Dispersive X-Ray Analysis) unit integrated into SEM and also XRD (X-ray diffraction) device were used for chemical analysis. After the microstructure and chemical analysis processes, hardness measurements were carried out on the boride layers formed on the surface of the samples. After the microstructure and chemical analysis processes, the hardness of the boride layers formed on the surfaces of the boronized samples was measured with a Vickers hardness device, using a 100 g. weight.As a result of the analyzes carried out, it was determined that AISI M2 high-speed steel can be borided, and it was determined that the boride layer formed on the surface was single-phase, unlike many steel types, and this phase was Fe2B. In addition, the results obtained were compared with the literature and the accuracy of the results was confirmed.
The Effect of Welding Positions on the Weldability of X20CrMoV11-1 Steels
(2018) İş, Emine Gündoğdu; Topuz, Polat; Gümüş, Emre; Çiçek, Bünyamin
In the study, mechanical properties of martensitic steel X20CrMoV11-1 was investigatedafter being welded using Tungsten Inert Gas (GTAW) welding method at different weldpositions (PC and PJ-EN 6947). The X20CrMoV11-1 steels have been widely used in thermalpower plant applications in combustion chambers and other high-temperature parts. Thesematerials experience extremely high internal pressure at the service conditions. WCrMoV12Si was used as the filler metal in the welding. The GTAW welding process was conducted ina controlled manner and all the parameters used during the process was monitored. The postwelding heat treatment was applied in order to eliminate the variations in the hardness of thewelded materials. The samples were characterized using tensile, bending, hardness, and notchimpact tests. Macro photographs were taken from the samples to observe the transition areas.The results indicated that the mechanical properties obtained from the samples welded in PCposition were higher than those obtained from PJ position.
The Fracture Toughness of Fe2B Formed on Boronized AISI 304
(Carl Hanser Verlag, 2014) Topuz, Polat; Gundogdu, Emine; Yilmaz, Eren; Gumus, Emre
In this study, the fracture toughness of Fe2B boride layer on boronized AISI 304 stainless steel was investigated. Samples were boronized in an indirect heated fluidized bed furnace with Ekabor 1 (TM) boronizing agent at 1123 K, 1223 K, and 1323 K for 1 h, 2 h, and 4 h, respectively. The boride phases were investigated by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indentation. With increasing boriding temperature and time the fracture toughness values were reduced. The boride layer thickness formed on the boronized samples ranged between 12 mu m and 176 mu m. The hardness of the borides ranged between 1709 HV0.1 and 2119 HV0.1 and fracture toughness was in the range of 2.19-4.47 MPa x m(1/2) depending on the layer thickness and hardness.
Wear properties of borided WC-Co
(Walter De Gruyter Gmbh, 2023) Aydogmus, Tuna; Peker, Derya; Topuz, Polat
Today, artificially produced tungsten carbide (WC) tools are used as an alternative to diamonds such as mining, drilling, cutting, or machining. Although it is called WC, it also contains a certain amount of cobalt (Co). The most important reason for this is that it increases the wear resistance of the WC. Boriding is a type of surface hardening method that provides wear, hardness, and corrosion resistance to the applied surface. In boriding, which is a kind of diffusion process, there is no change in the dimensions of the materials since the boride layer grows from the outer surface of the materials to the inside. In this study, the development of surface properties by boriding of 90 wt% WC and 10 wt% Co-containing abrasive bits used for drilling were investigated. The samples were borided in an atmosphere-controlled furnace at 1173, 1273, and 1373 K for 1, 2, and 3 h by the pack boriding method. After the boriding processes, the microstructure, hardness, and chemical composition of the boride layers formed on the surface of the samples were examined, and finally, the wear tests were carried out to reveal the differences compared to the unborided sample.
Yüksek Kaynak Özelliklerine Sahip Nano Partikül Alaşımlı Özlü Kaynak Tellerinin Geliştirilmesi
(2019) Özbek, Sunullah; Koçak, Mustafa Murat; Keskinkılıç, Ali Selçuk; Kozbe, İlknur Koçaş; Topuz, Polat
Boru hatları veya kıyıdan uzak rüzgar parkları gibi birçok yapı, yüksek mukavemet ve iyi isleme yeteneklerine sahip malzemelerden imal edilirler ve bu yapılarda yüksek tokluk büyük önem arz etmektedir. Adı geçen yapıları olusturmak için, bu tür malzemelerin birlestirilmesi gerekmektedir. Bu tür yapıların kaynaklı birlesim bölgelerindeki düsük tokluk, stabiliteyi ve güvenirligi etkileyen en önemli problemlerden biridir. Kaynak dikisinin ve ısıdan etkilenen bölgenin (Isının Tesiri Altındaki Bölge /ITAB) toklugu, ana metalin toklugu düzeyinde muhafaza edilmelidir. Bu tür yapılardan beklenen son derece yüksek seviyedeki özellikler, arastırmacıları yeni kaynak yöntemlerini ve kaynak malzemelerini gelistirmeye özendirmistir. Örnek olarak, yeni ve henüz yeterince test edilmemis lazer hibrit kaynak yöntemi söylenebilir. Bununla beraber, bilinen kaynak yöntemleri uygulamalarında, kaynak dikis kalitesini artırmak için yeni nesil kaynak sarf malzemelerinin gelistirilmesine ihtiyaç duyulmustur. Bu çalısmanın amacı da söz konusu ihtiyaca cevap verebilecek nano teknoloji ile üretilen Al2O3, TiO2 ve ZrO2 tozları veya Fe-Al2O3 gibi nano kompozit tozları içeren yeni tip özlü kaynak telleri (Flux Cored Wires /FCW) gelistirmektir. Bu oksitler, yüksek tokluk ile metalürjik olarak ince taneli mikroyapı üreterek kaynak metal dolgusu üzerinde olumlu bir etki saglayacaktır. Yapılan nanotoz sentezleri ve bunların üretime uygulama çalısmaları sonucu elde edilen ürünler standart mekanik testlere tabi tutulmustur. Sonuçlar, toklugun standart özlü kaynak teli ile yapılan kaynaklara göre önemli ölçüde iyilestirdigini, -20oC da yapılan testlerde yaklasık %30 artıs sagladıgını göstermistir.

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