Yazar "Demir, Bilge" seçeneğine göre listele
Listeleniyor 1 - 20 / 27
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Alimünotermit kaynağıyla birleştirilmiş, mantarı sertleştirilmiş “r350ht” rayın boyuna sertlik taramasının incelenmesi(2023) Arı, Adem; Demir, Bilge; Keskin, AtilaGünümüzde ray ömrünü uzatan sıcak hadde sonrası kontrollü ve hızlı soğutmayla ray mantar sertleşmesi sağlanarak önemli ekonomik kazançlar elde edilmektedir. Ray kaynak metotlarından Aluminotermit kaynağı saha birleştirme yöntemi olarak günümüzde de önemini devam ettirmektedir. Kaliteli bir termit kaynağı yapmak için termit alaşımının sıkı denetimi ve ateşlemeden sıvı çeliğin hazneye dolmasına kadar geçen kademelerin kontrollü bir şekilde yapılması gerekir. Bütün bu ön koşullar tavsiye edildiği şekilde yerine getirilmiş olsa bile ve hatta mikro hatalar da olmasa, yine de kaynağın mekanik özellikleri rayın kendi özelliklerinden düşük kalır. Ray termit kaynağı, basitliği, taşınabilirliği ve ekonomisi nedeniyle demiryolu endüstrisi için değerli bir kaynak teknolojisidir. Bununla birlikte özellikle termal işlem ile üretilen R350HT mantarı sertleştirilmiş rayların birleştirmesinde yüksek ısı, kaynağın ulaştığı maksimum sıcaklık derecesine, bu sıcaklıkta kalma süresine ve soğuma hızına bağlı olarak kritik dönüşümlere sebep olabilmekte ve bunlar ray ömür ve performansını oldukça etkilemektedir. Bundan dolayı bu çalışmada R350HT mantarı sertleştirilmiş rayın Aluminotermit kaynaklı birleştirmeden kaynaklanan sertlik yapısının kaynak parametrelerine bağlı olarak değişimi ve gelişimi incelenmiş ayrıca ilgili uluslararası standartlara uygunluğu ve avantajları araştırılmıştır. Bu makale, esas olarak ısı tesiri altında kalan bölge (ITAB) olmak üzere, kaynaklı ray bağlantılarının sertlik değişimini etkileyen faktörler açısından incelemeyi amaçlamıştır. Deneysel çalışmalar da R350HT mantarı sertleştirilmiş ray numuneleri 120 cm uzunluğunda kesilerek hazırlanmış ve bu numunelere sow-5 yöntemli alüminotermit kaynağı uygulanmıştır. Esas kaynak bölgesiyle ITAB bölgesindeki boyuna sertlik taraması TS EN 14730-1+A1 standardı ile de karşılaştırılarak kritik yapılmıştır. SkV Elite L25 ve Pandrol firmasının PLA yöntemli termit kaynaklarının eğme ve yorulma deneyi sonuçları, standartları karşılamadığı için çalışmalara sow5 yöntemiyle kaynaklanmış ray numuneleriyle devam edilmiştir [7] Deney sonuçlarında sow5 yöntemli termit kaynağının istenilen standartlara en uygun yöntem olduğu bulunmuştur. Deneysel sonuçlar bu çalışmada kullanılan parametrelerle üretilen kaynaklı birleştirmelerin bu standartlara uygunluğunu göstermiştir.Öğe Analytical and Experimental Investigation of Product Geometry and Dimensional Accuracy in the Punching Process of AA 1050 and AA 1070 Sheets(Gazi Univ, 2024) Yetgin, Abdullah; Demir, Bilge; Gurun, Hakan; Ali, Khalil BelrasPunching is a widely used and economical manufacturing method. The forces that occurred during punching and the dimensional accuracies of the parts obtained from punching are significant in manufacturing processes. This study aimed to examine the cutting forces that occur in the punching process and the dimensional accuracy of the parts. AA 1050 and AA 1070 sheet materials were used in the experimental studies. Five punches with various cutting-edge geometries were employed in the punching processes. Punching operations were carried out at a constant clearance value and press speed. The geometries of the specimens obtained from the experimental studies were examined using stereo and shuttle-pix microscopes. In addition, the finite element method was used to study punching processes. The consistency of the finite element model was analyzed by comparing experimental and numerical studies. When the flat punch geometry was used, the cutting force was at its greatest. Using the largest angled punch geometry resulted in the lowest cutting force. It has been determined that the dimensional accuracy of the blank and the falling part is better when using the flat punch geometry compared to the other punches used. In addition, it was observed that experimental and theoretical studies are compatible with each other. It is thought that finite element software can provide time and cost savings in determining the cutting force of materials.Öğe A comparative study on the machinability of ?-type novel Ti29Nb13Ta4.6Zr (TNTZ) biomedical alloys under micro-milling operation(Elsevier Sci Ltd, 2023) Aslantas, Kubilay; Demir, Bilge; Guldibi, Ahmet Serdar; Niinomi, Mitsuo; Dikici, Burakbeta-type Ti29Nb13Ta4.6Zr (TNTZ) alloy is a new-generation alloy that does not contain toxic/allergic elements. The alloys have low Young's modulus (-60 GPa) close to the cortical bone, providing excellent biocompatibility over familiar commercial CP Ti or Ti6Al4V ELI. Different macro/micro-machining methods can be used to obtain the final shape of Ti alloys and impact on the implant's bio ecosystem and performance. This study compared the micro-mill machining performance of the TNTZ alloys with commercial CP Ti and Ti6Al4V ELI. Machining ex-periments were performed under similar and different cutting speeds and constant feed rate conditions. In the study, cutting forces, surface roughness, burr size and tool wear were obtained. The results showed that the Fx cutting forces for TNTZ are about 3 and 2 times higher than for CP Ti and Ti6Al4V alloys, respectively. Depending on the increasing cutting distance, the surface roughness of CP Ti and Ti6Al4V materials followed a similar trend. However, the surface roughness values for TNTZ alloy are higher and decrease with increasing cutting distance. Burr widths for CP Ti and Ti6Al4V are similar, but the milling direction at which maximum burr occurs varies. In the TNTZ alloy, the burr width is about 3 times higher, and the burr occurred inside the slot, not at the edge of the machined slot. The predominant type of damage in milling Ti6Al4V and CP Ti materials is abrasive and adhesive. The dominant damage type in TNTZ alloy is chipping. Increasing the number of revolutions in TNTZ causes the cutting forces and burr width to increase.Öğe Effect of functionalized graphene nanoplatelet dispersion on thermal and electrical properties of hybrid carbon fiber reinforced aviation epoxy laminated composite(Elsevier Science Sa, 2024) Bilgi, Cahit; Demir, Bilge; Aydin, Hamide; Ustun, Burcu; Kurtan, UmranCarbon fiber reinforced polymers (CFRP) alone cannot meet the increasing requirements of the aerospace industry. Therefore, graphene nanoplatelets (GNPs) dispersed homogeneously in the matrix offer unique advantages. This study aimed to increase the thermal and electrical properties by adding functionalized GNPs (f f-GNP) to the aviation epoxy matrix (Araldite LY5052) in CFRP at different rates (neat- 0.5-1-1.5 wt%) for the first time and to provide homogeneous dispersion with surfactant. The results showed that FGNP as an additive achieved significant homogeneity. While the glass transition temperature (Tg) g ) in the neat composite is 121 degrees C, it is 123 degrees C, 127 degrees C and 133 degrees C in nanocomposites with 0.5-1-1.5 wt% additives, respectively. In addition, the melting point is 366 degrees C in the neat composite and 368.6 degrees C, 370 degrees C, and 370.3 degrees C in the nanocomposites with 0.5-1-1.5 wt% additives, respectively. The oxygen groups in the additive increased the energy barrier, thus increasing the percolation threshold. There was a 50 % increase in electrical conductivity in the sample with 0.5 wt% doping with bulk current density and an 18 % increase with 1 wt% doping with surface current density. Meanwhile, the it-it bonds formed by the surfactant with GNPs and the hydrogen bonds formed with the matrix served as a bridge by filling the gaps in the interphase, significantly increasing the flow of heat and electricity.Öğe Effect of MWCNT on the properties of NCF-CFP hybrid composite fabricated via vacuum infusion(Sage Publications Ltd, 2023) Pektuerk, Hatice Yakut; Demir, Bilge; Bilgi, Cahit; Oez, Fatih; Ersoy, NuriThis work is an attempt to evaluate the effect of multi-wall carbon nanotube (MWCNT) reinforcement on the properties of non-crimp fabric (NCF) carbon fiber-reinforced polymer hybrid composite (CFRP). MWCNT NCF-CFRP plates were produced by vacuum infusion. Epoxy-MWCNT mixtures were prepared by adding a surfactant, Triton-X 100, and ethanol and mixing ultrasonically. The plates were subjected to thermal and electrical conductivity, DSC and FT-IR characterizations, and tensile testing. SEM image analyses evaluated tensile fracture surfaces. Results showed that 0.5 wt% MWCNT-reinforced nanocomposite samples exhibited better tensile properties than pure NCF-CFRP composites and other nanocomposite samples. The 1.5% MWCNT reinforced sample was the best conductor at all temperatures. The temperature increases also increase the conductivity. However, the conductivity value of 0.5% MWCNT reinforced material increased significantly at low frequencies such as 100-10,000 Hz. The heat reaction of the 0.5 wt% MWCNT nanocomposite was also a bit higher than that of 1-1.5 % wt MWCNT nanocomposites, indicating a decrease in the cure.Öğe The Effects of the Welding Parameters on Tensile Properties of RSW Junctions of DP1000 Sheet Steel(Eos Assoc, 2018) Elitas, Muhammed; Demir, BilgeIn this study, the maximum tensile shear load bearing capacity of the resistance spot welded DP1000 steel was measured and the tensile shear properties of the joints were evaluated. The effects of different welding parameters on microstructure, microhardness and tensile shear properties were investigated. Weld processes were performed by using 5kA and 7kA weld currents and 2-6bar electrode pressures. The microstructure of the welded materials was evaluated and the hardness profiles were determined. Experimental results showed that increasing electrode pressure and weld current increased the tensile shear load bearing capacity. It was also observed that the expulsion had a negative effect on the tensile shear load bearing capacity.Öğe Evaluation of the effect of MWCNT amount and dispersion on bending fatigue properties of non-crimp CFRP composites(Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Pekturk, Hatice Yakut; Elitas, Muhammed; Goktas, Mustafa; Demir, Bilge; Birhanu, SalihMulti-walled carbon nanotubes (MWCNTs) have many unique features that improve composite material properties, including a large surface area, thermal and chemical stability, and thermal and electrical conductivity. Our study aimed to examine the influence of MWCNT weight percentage on the fatigue characteristics of a polymer matrix composite strengthened with carbon fiber in fabric form. This study aimed to explore the additional properties and functions of these MWCNTs. For the experiments, MWCNTs were prepared by mixing them in solution with epoxy in three different weight percentages (0.5 %, 1.0%, and 1.5%) using a surfactant, and at 0.5 wt% without a surfactant. The prepared solutions were injected into four-axis non-crimp carbon fiber fabric plates via the vacuity mixture method and then cured for 48 h to produce nanocomposite plates. Using five types of composites, fatigue tests were carried out at six different amplitudes and a fixed frequency. Fatigue test specimens were subjected to detailed SEM analysis of their fatigue fracture surfaces. The investigational results revealed that the 0.5 wt% MWCNT epoxy solution had been homogeneously dispersed and exhibited the highest absorbance spectrum. The 0.5 wt% MWCNT specimen achieved the highest value in the fatigue life experiments. In addition, electron microscopy studies of the fracture surfaces of the test specimens determined that individual COOH-MWCNTs interrelated with the fibers and formed a bridge between fiber and matrix, whereas agglomerations caused weak bonding between the reinforcement fibers and matrix, making the material more brittle.(c) 2021 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Öğe Finite element modelling of the fatigue damage in an explosive welded Al-dual-phase steel(Walter De Gruyter Gmbh, 2023) Elitas, Muhammed; Goktas, Mustafa; Acarer, Mustafa; Demir, BilgeIn this study, production of dual phase steel-Al 1100 aluminium alloy laminated composite by explosive welding and investigation the microstructural and mechanical properties especially fatigue life of the composite and its components were aimed. Finite element analysis (FEA) was used to simulate the bending fatigue tests of the Al 1100-DP steel (LITEC 1050) bimetal. A semi-wave at the explosive interface with intermetallic was obtained as a microstructural result. Hardness was increased near the interface due to deformation and intermetallic formation at the explosive weld interface. The impact test results showed that the samples' impact toughness was enriched by fabricating steel-Al laminated composite. The results also showed that the Al 1100-DP steel (LITEC 1050) bimetal composite properties were appropriate to the composite theory and satisfied strength-ductility relations accomplished. Additionally, the bending fatigue test and FEA results were compatible. Moreover, fatigue cracks were observed at the explosive weld interface between Litec DP steel and intermetallic but not at the Al-intermetallic interface.Öğe Hybrid Reinforced Magnesium Matrix Composites (Mg/Sic/GNPs): Drilling Investigation(Mdpi, 2018) Abdulgadir, Mustafa M.; Demir, Bilge; Turan, Muhammet EmreThe machinability of graphene-reinforced magnesium-based hybrid nanocomposites produced through the application of powder metallurgy method has not been completely reported. This article presents an experimental investigation on the thrust force, the surface roughness (R-a), and drilled surfaces characteristics in the drilling process of a Mg/SiC/GNPs (magnesium matrix based silicon carbide and graphene nanoplatelets) hybrid magnesium matrix composite. The hybrid composite material was produced through the application of a powder metallurgy method. The experiments were carried out with uncoated, PVD (Physical Vapor Deposition), and CVD (Chemical Vapor Deposition) coated tungsten carbide drill bits at three levels of cutting speeds (30, 40, and 50 m/min), and three different levels of feed rate (0.10, 0.15, and 0.20 mm/rev) under dry machining conditions. Taguchi's L-27 (3(3)) orthogonal array and S/N ratio were used to optimize the optimal parameters for thrust force and surface roughness. The experimental results indicated that the thrust force and the surface roughness were extremely dependent on a particular type of drill bits, feed rate, and cutting speed. The feed rate parameter is known to have a significant influence on the surface finish.Öğe INFLUENCE OF PUNCH SHAPES ON FORCES AND PART QUALITY IN THE PUNCHING OF EXPLOSIVELY WELDED DP600, A11100, AND DP600-A11100 COMPOSITE PLATES(Univ Zagreb Fac Mechanical Engineering & Naval Architecture, 2022) Ali, Khalil Belras; Demir, Bilge; Gurun, Hakan; Acarer, MustafaThis study theoretically and experimentally investigates blanking/piercing operations of explosively welded commercial DP600 advanced steel sheets, Al1100 aluminium sheets, and DP600-Al1100 composite plates, in which punches with different tip shapes are used. The experimental studies included several methods, such as explosive welding, punching, tensile testing, and macro image analyses using digital, optical, and SEM microscopes. The theoretical studies comprised finite element modelling using 3D models. The explosive weld was successfully applied, and the obtained Fe-Al weld microstructure was evaluated. A total of five punches, which have different tip shapes -flat-ended (0??), angled (16??), concave (R1 and R2), and V-shaped (V16) tips -were used in the experiments. Blanking forces were obtained using a load cell mounted to the die, a data acquisition card, an amplifier, and computer software. The simulation and the experimental study results were in agreement and clearly showed the effects of the punch shear angle and shape on the forces required for blanking/piercing.Öğe An investigation of mechanical and metallurgical properties of explosive welded aluminum-dual phase steel(Elsevier, 2008) Acarer, Mustafa; Demir, BilgeThe aim of this paper is investigation of microstructure and property relationship in aluminum-HSLA steel and aluminum-dual phase steel bimetals fabricated by explosive welding technique. Dual phase steel was produced by intercritical annealing and water quenching from 1.45Mn-0.2Si-0.186C HSLA steel. Hardness. tensile shear strength. tensile strength, toughness and microstructure of explosively welded aluminum-HSLA steel and aluminum-dual phase steel were evaluated. Both bimetals have a straight bonding interface. It was also seen that plastic deformation of dual phase steel was higher than HSLA steel near interfaces of bimetals. The hardness was increased near the bond interface of bimetals. Tensile and tensile shear strength tests showed that aluminum-dual phase steel is superior than aluminum-HSLA steel. Also, impact toughness of aluminum-dual phase steel was found significantly higher than that of aluminum-HSLA steel. (C) 2008 Elsevier B.V. All rights reserved.Öğe An Investigation of Mechanical and Wear Performance of TiB2/GNPs-Reinforced ZK60 Mg Matrix Composites Fabricated Via Powder Metallurgy(Springer, 2023) Mustu, Mustafa; Demir, Bilge; Aydin, FatihIn this study, ZK60 alloy, ZK60/15 wt.% TiB2, and ZK60/15 wt.% TiB2 - 0.5 GNPs composites were prepared by hot pressing. The density, microstructure, hardness, and tribological and compression behavior of the samples were investigated. Microstructure investigations showed that TiB2 particles were generally homogeneously dispersed, but GNPs particles were agglomerated. Under 10 and 40 N loads, the best wear performance was obtained with 15 wt.% TiB2 - 0.5 GNPs and ZK60/15 wt.% TiB2 samples, respectively. Abrasion at low and delamination at high loads were observed as the dominant wear mechanism. According to the mechanical test results, the highest hardness (87.1 HV), compressive yield strength (290.1 MPa) and ultimate compressive strength (379.2 MPa) were obtained for the ZK60/15 wt.% TiB2 composite. Fracture surface investigations showed that the mechanism was cleavage fracture and the presence of crack formations on the surface.Öğe An investigation of the PMEDM processing and surface characterizations of AZ61 matrix composites via experimental and optimization methods(Elsevier Science Sa, 2023) Mustu, Mustafa; Demir, Bilge; Aydin, Fatih; Gurun, HakanIn this study, AZ61/15 wt%TiB2 and AZ61/15 wt%TiB2-0.5 wt%GNPs composites were manufactured by hot pressing, and the machinability of the produced samples was carried out by powder mixed electrical discharge machining (PMEDM). The influence of PMEDM parameters, namely pulse on time, current and materials, were studied by surface roughness (SR) and material removal rate (MRR) using the Taguchi design. The microstructure and surface quality of the machined surfaces and cross-sections were investigated using 3D microscopy, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). Results showed that PMEDM produced a melting, white layer and transition zone direct proportionally to the processing parameters. The white layer did not differ from the metal integrity of the transition zone. Additionally, volcanic craters, holes, cracks, debris covered with molten metal, and reinforcement particles were observed at the machined surface and cross-section. A high amount of oxygen was detected on the machined surface as a result of the interaction between kerosene and generated heat changing proportionally to the amount of the EDM parameters. The analysis of variance (ANOVA) showed that the pulse on time and materials, with 65.46% and 40.86%, were the most significant parameters on the SR and MRR, respectively. For regression models, the determination coefficient (R2) for the prediction of SR and MRR was noted to be 0.98 and 0.85, respectively.Öğe An investigation of the shearing performance and sheared surface characterisation of ultra-strength DP steel-Al explosive welded plate composite(Springer London Ltd, 2023) Demir, Bilge; Ali, Khalil Belras; Gurun, Hakan; Acarer, MustafaThis study investigated the manufacturability of ultra-strength steel-Al plate composite, the punch-cutting performance of these composites and base materials, and the cutting surface properties. Therefore, experimental studies included explosive welding, punching process, and materials characterisations (microstructure and sheared surface image analyses via SEM, hardness and tensile test). In the punching process, five different types of punches were used. Additionally, the load cell was mounted on the punch and connected to the computer by an amplifier and a data acquisition card; the force values corresponding to the processing times were directly monitored, and the data were obtained. Shear process analyses were performed using finite elements. Microstructure and mechanical test results show that the DP1200 steel-Al 1100 aluminium laminated bimetal composite was produced by explosive welding of acceptable quality. The flat punch showed the highest shearing force, and other punches (angled and concave ends) reduced the shearing forces P R2, P V16, P R1, and P 16, respectively. Punches with different cutting-edge forms reduced the shearing force by up to 75%. The sheared surfaces were investigated in detail. Shearing marks were observed on both sides of the bimetal similarly. The punching process force vs time results showed good agreement between modelling and experimental punching values.Öğe Investigation of the tensile shear property of DP600 steel combined with resistance spot welding(Pamukkale Univ, 2022) Demir, Bilge; Elitas, Muhammed; Karakus, HuseyinThis study focused on optimization of different electrode tip types (Conical round, Flat R3, Flat R6, Flat conical) and welding current parameters to obtain the ideal tensile shear strength of resistance spot welded DP600 steel. Welding processes were carried out at 5 and 7 kA welding currents for each of the 4 different tip types. Experimental results showed that welding current is the most important variable affecting tensile shear strength. As the welding current increased, the tensile shear strength increased. It has been determined that there is a linear relationship between the nugget diameter value and the tensile shear strength. The highest tensile shear strength values were obtained with flat 3 mm radius electrode tips and the lowest with conical round tip electrodes.Öğe An Investigation of TIG Welding of AZ31 Magnesium Alloy Sheets(Carl Hanser Verlag, 2014) Demir, Bilge; Durgutlu, AhmetIn this study, butt welding of commercial AZ31 magnesium alloy sheets has been investigated by using the tungsten inert gas welding process with alternating and pulsed current. Magnesium alloy welding, although well developed and understood, can present some problems, such as porosity, hot cracking, oxide formation, etc.. Samples of the welded parts have been examined by optic microscopy and mechanic tests. Results showed that porosities and homogeneous micro size oxides were rarely found. Orientation of the weld microstructure in direction of the heat transfer were also rarely observed and equiaxed grain morphology was the dominant grain structure as in the base metals. In addition, fusion zone and HAZ of the welded samples have generally shown twins. This seems to be a very dominant grain type particularly in pulsed samples. Hot cracking was not observed in any samples. Results of mechanical tests showed that pulsed current seems to generate more favorable higher mechanical properties of weld joints than alternating current for magnesium alloys.Öğe An investigation on bending fatigue in a corrosive environment of dual-phase 1000 sheet steel RSW joints and damage model via experiment and numeric analysis(Sage Publications Ltd, 2024) Goktas, Mustafa; Demir, Bilge; Elitas, MuhammedFatigue, corrosion, and fatigue damage models are best addressed to improve and understand the service performance of materials, particularly automotive steel. This study is an attempt to experimentally and finite element investigates plain bending fatigue performance and damage model of DP 1000 sheet steel resistance spot welding (RSW) joints in 3% NaCl aqueous corrosive treatment. RSW applications were carried out using different weld currents. The joint samples were then subjected to optical image analysis, tensile shear, and fatigue tests (3% NaCl-aqueous and normal atmosphere). A proper damage model of RSW junctions was developed and corrected by numeric analysis. Besides, RSW nugget formation, tensile shear, and plain bending fatigue tests were also applied. Consequence, fatigue behavior, tensile load carrying capacity, and effective fracture behavior of resistance spot welded joint specimens were evaluated. Results showed that a corrosive environment negatively affected fatigue performance. With the developed model, it was observed that the fatigue life of the samples decreased by 30-35% in the fatigue tests performed in the corrosive environment. Experimental and numerical analysis results of plain bending were compatible.Öğe Microstructure, mechanical properties, and corrosion resistance of an explosively welded Mg-Al composite(Keai Publishing Ltd, 2022) Acarer, Mustafa; Demir, Bilge; Dikici, Burak; Salur, EminIn this study, an attempt was made to manufacture an AZ31-Al5005 laminated composite by explosive welding. A mixture of ammonium nitrate (90%), fuel oil (5%), and TNT (5%) was used as the explosive. The detonation velocity of the explosive material was approximately 3100 m.s(-1). The microstructure and mechanical and corrosion properties of the joint were comparatively investigated. Microstructural characterisation of the joint was conducted by optical microscopy (OM), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). The mechanical properties were determined using micro-Vickers hardness, tensile, and Charpy impact tests. In addition, electrochemical tests were conducted on the AZ31-Al5005 laminated composite and the individual components to determine their corrosion resistance. The corrosion behaviours of the structures were determined in a 3.5% NaCl solution at room temperature using potentiodynamic scanning (PDS). The metallurgical structure and mechanical properties of the joints were within the acceptable limits. (C) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.Öğe Nokta direnç kaynağı ile birleştirilen geliştirilmiş yüksek mukavemetli çeliğin mekanik özellikleri üzerinde elektrod uç tipinin etkisinin incelenmesi(2021) Demir, Bilge; Elıtaş, Muhammed; Karakuş, HüseyinBu çalışmada, nokta direnç kaynak yöntemi ile birleştirilen geliştirilmiş yüksek mukavemetli çeliğin kaynak çekirdek çapı, çekme makaslama dayanımı ve mikrosertlik özellikleri üzerinde farklı elektrot uç tiplerinin etkisi incelenmiştir. Bu amaçla, özellikle otomotiv sektöründe tercih edilen konik yuvarlak, düz R3, düz R6 ve düz konik elektrot uçlar kullanılarak nokta direnç kaynaklı birleşimler gerçekleştirilmiştir. Deney numuneleri, kaynak çekirdeği geometrisi makro-mikro incelemesi, mekanik ve metalürjik incelemelere tabi tutulmuştur. Deneysel sonuçlar kaynak çekirdek çap değeri, mikro sertlik sonuçları ve çekme makaslama dayanım değerleri arasında doğrusal bir ilişki olduğunu göstermiştir. Düz 3 mm yarıçap uçlu elektrotlar ile en yüksek, düz konik uçlu elektrotlar ile en düşük çekme makaslama dayanım değerleri elde edilmiştir.Öğe An Optimization Study on Resistance Spot Welding of DP600 Sheet Steel via Experiment and Statistical Analysis(Eos Assoc, 2023) Alzahougi, Abdulkarim; Demir, Bilge; Elitas, MuhammedResistance Spot Welding (RSW) is widely used in many automotive, boiler, and ship manufacturing industries. Therefore, the optimization and effectiveness of the RSW process are very useful and cost-efficient processes in addition to improving weld quality. This study used various welding parameters to investigate the optimization of the RSW process of Advanced High Strength Steel (AHSS). RSW was carried out using different welding times, currents, and electrode pressure values. Microstructural analysis, nugget formation, and tensile shear test were performed on samples. This study applied the Taguchi method and ANOVA to set up the welding process and optimize its results. Microstructural characterization showed that the weld nugget microstructures had a high-volume fraction of martensite. Using the Minitab software, Taguchi (DOE) and ANOVA on the tensile shear test results showed that welding current is more effective than clamping pressure on the tensile shear load-bearing capacity (TLBC). However, clamping pressure affects the weld current effects on weld performance. Additionally, the TLBC of RSW samples increases, whereas increasing the clamping pressure leads to a decrease in TLBC and nugget dimensions. Consequently, a detailed analysis of the RSW coefficients and their effects led to optimized results.
