Kaynak Teknolojisi Uygulama ve Araştırma Merkezi
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Güncel Gönderiler
Öğe Dövme ve eklemeli imalat yöntemiyle üretilmiş inconel 625 alaşımların termal yöntemle hızlı delinmesinde elektrot aşınmasının incelenmesi(Marmara Üniversitesi, 2023) Ceritbinmez, Ferhat; Günen, Ali; Gürol, Uğur; Çam, GürelÜretildikleri 1950’li yıllardan beri havacılık, uzay, nükleer, biyomedikal endüstrisi gibi ileri mühendislik uygulamalarında sıklıkla tercih edilen Inconel grubu alaşımların daha maliyet etkenli bir yöntem olan eklemeli imalat yöntemiyle üretilebilirliği son 20 yılda yoğun olarak çalışılmaktadır. Ancak, süper alaşımlar işlenebilirliği zor malzemeler grubunda olup, iletkenlikleri zayıf olduğundan bu alaşımların delinmesinde kullanılan elektrotlarda ciddi hasarlar meydana gelmektedir. Dahası, eklemeli imalat yöntemiyle üretilen bu alaşımların delinebilirliğinde kullanılan elektrotlardaki aşınmayı inceleyen sınırlı sayıda çalışma vardır. Bu amaçla bu çalışmada, dövme ve eklemeli imalat tekniği ile üretilmiş Inconel 625 alaşımların, EDM ile hızlı delik delme yöntemi kullanılarak 3 mm çapında pirinç elektrotlarla delinmesi neticesinde aşınan elektrotlarda oluşan aşınma miktarları incelenmiştir. Elektrot aşınması; iş parçası üzerinden ölçülen delik çapları ve kerf açıları dikkate alınarak analitik olarak ve deneylerde aşınan elektrotların hassas terazilerle tartılması ile fiziksel olarak tespit edilmiştir. Daha tok ve kararlı bir yapıda olan dövme Inconel malzemeyi işleyen elektrodun eklemeli imalat Inconel alaşımı işleyen elektroda göre % 108,33 daha fazla aşındığı tespit edilmiştir. Buna ilaveten, dövme Inconel iş malzemesinde elektrot aşınmasından kaynaklı kerf açısının eklemeli imalat Inconel malzemeye göre % 80,06 daha fazla olduğu görülmüştür.Öğe S355J2 yapı çeliklerinin toz altı ark kaynağında dolgu metalinin mikroyapı ve mekanik özelliklere etkisi(İdris Karagöz, 2024) Varol, Abdullah; Bozan, Mehmet Safa; Çoban, Ozan; Gürol, UğurBu çalışmada 20 mm kalınlığa sahip S355J2 yapı çeliğine EN ISO 14171-A standardına göre üretilmiş GeKa S1, S2Si ve S3Mo dolgu metalleri kullanılarak toz altı ark kaynağı yöntemi ile alın kaynağı prosesi gerçekleştirilmiştir. X kaynak ağzı geometrisi ve 600 kaynak ağzı açısı ile EN ISO 147174 standardına uygun olarak üretilmiş alüminat bazik Eliflux BFPP (SAAB66ACH5) tozu kullanılarak kaynak işlemleri uygulanmıştır. Kaynak prosesi sonrasında tahribatsız muayene, makro yapı incelemesi, mikroyapı incelemesi ile mikrosertlik, eğme, çekme ve -20 0C’de kaynak metali ve ısıdan etkilenmiş bölge (IEB)’den çentik darbe testleri gerçekleştirilerek kaynaklı yapılar karakterize edilmiştir. Farklı dolgu metalleri kullanılarak elde edilen kaynaklı yapıların özellikleri kıyaslanarak kullanım alanında beklenen performansa yönelik olarak dolgu metali seçimi için mikroyapı – mekanik özellik ilişkisi kurulmuştur. Elde edilen sonuçlar S1 dolgu metali ile yapılan kaynakların kaynak bölgesinden; S2Si ve S3Mo dolgu metalinde ana malzemeden koptuğunu göstermiştir. Her üç kaynakta da akma ve çekme dayanımı ve %uzama değerlerinde bariz bir farklılık gözlenmemiştir. Fakat S1’e kıyasla S3Mo kullanımı nedeniyle kaynak metali ve IEB’deki çentik darbe dayanımında sırasıyla %15 ve %166, mikrosertlikte %37 ve %8’lik artış sağlanmıştır. Sonuç olarak denizcilik endüstrisinde kullanılan yapı çeliklerinin kaynak uygulamalarında S2Si ve S3Mo dolgu metallerinin kullanımının mikroyapı ve mekanik özellikler açısından uygun olduğu fakat maliyet/performans açısından değerlendirildiğinde ise S2Si teli kullanımının, düşük sıcaklıklarda yüksek darbe dayanımı gereksiniminin arttığı kritik uygulamalarda ise S3Mo dolgu metali kullanımının daha uygun olacağı ortaya koyulmuştur.Öğe Mechanical and ballistic performance of high-hardness armor steels welded with ASS-LHF sandwich joint design(Elsevier Ltd, 2025) Gürol, Uğur; Çelik, Ceren; Çoban, Ozan; Göçmen, Müesser; Koçak, MustafaArmor steels are widely recognized for their exceptional mechanical and ballistic performance, particularly in the fabrication of armored vehicles. Austenitic stainless steel (ASS) wires are commonly used in their welding processes to mitigate hydrogen-induced cracking. However, joints formed using ASS often suffer from reduced ballistic performance due to the strength mismatch (undermatching) compared to the base material. This study explores the application of butt joints, integrating low hydrogen ferritic (LHF) deposits between softer ASS weld layers, which can be expressed as sandwich layer design, in gas metal arc welded (GMAW) armor steel plates. The mechanical properties were evaluated through hardness, tensile, and Charpy V-notch impact tests. Ballistics test performances were measured using depth of penetration (DoP) and width of penetration (WoP) values. The microstructural analysis utilized stereo, optical, and scanning electron microscopes. The results demonstrated that the sandwich joint configuration met the Charpy-V impact toughness requirements of the base metal, achieving 31.4 J and 65 J at −40 °C for the WM and HAZ regions, respectively, compared to 20 J for the base material. Moreover, this innovative joint design effectively combined the high toughness and ductility of austenitic wire, reaching a low DoP value of 7.2 mm, with the superior strength of ferritic filler metal, which contributes to a low WoP value of 12.5 mm and a joint efficiency of 48 %. By combining these properties, the joint design significantly enhances ballistic performance in welded regions, traditionally considered vulnerable to ballistic threats, without compromising overall mechanical integrity.Öğe Microstructural and mechanical characterizations of weld metal of S960QL ultra high strength steel joints obtained with different multi-pass laying techniques using GMAW(Institute of Physics, 2024) Mert, Tolga; Gürol, Uğur; Tümer, Mustafa15 mm thick ultra-high strength steel plates with 960 MPa yield strength were welded using different multi-pass laying techniques (i.e., stringer and weaving beads) with torch manipulation. Weld metals obtained were compared using different mechanical (i.e., micro tensile tests and Vickers hardness maps) and microstructural (i.e., optical microscope, scanning electron microscope, x-ray diffraction, electron backscatter diffraction) characterization techniques. Coarser grains and acicular ferrite were observed in weld metal obtained with the weaving pass procedure. There were hardness differences in the face and root passes of both weld metals. Yet, hardness values were 19% and 11% higher for the face and root regions of the joint obtained by stringer pass procedure, respectively. Fractographs of micro tensile test specimens revealed dimples depicting ductile network structure for both joints.Öğe Su altı elektrotları ile yapılan kaynaklı birleştirmelerin mikro yapı ve mekanik özelliklerinin incelenmesi(Gazi Üniversitesi, 2022) Gürol, Uğur; Baykal, Hakan; Yıldız, Nur Benuse; Yılmaz, Can; Danışkan, Ömür; Koçak, MustafaBu çalışmada, rutil karakterli kaynak elektrotları ile düşük alaşımlı S355J2+N çelik plakaları kullanılarak su altında ve atmosferik şartlarda saf kaynak metalinin metalürjik özellikleri incelenmiştir. Su altı kaynakları, Türkiye’de ilk defa AWS A5.35 standardına göre özel olarak geliştirilen parafin kaplı GeKaTec UW E7014 su altı elektrotları kullanılarak açık denizde 4 metrelik bir derinlikte gerçekleştirilmiştir. İlk olarak, kaynaklı plakaların AWS A5.35 standardının gerekliliklerine göre tahribatsız muayeneleri yapılmıştır. Daha sonra mekanik özellikleri belirlemek ve deniz suyunun mikro yapısal dönüşüm üzerindeki etkilerini belirlemek için çekme testi, Charpy-V darbe testi, mikro sertlik testi ve mikro yapı incelemeleri gerçekleştirilmiştir. Her iki ortamda gerçekleştirilen kaynakların akma ve çekme mukavemetlerinde önemli derecede bir değişiklik olmadığını görülmüştür. Atmosferik şartlarda gerçekleştirilen kaynaklara kıyasla su altında gerçekleştirilen kaynakların %6-8 oranında daha sert olduğu ve % uzama değerleri ile -2°C’de elde edilen çentik darbe değerlerinin de sırasıyla %48 ve %22 oranında daha düşük olduğu tespit edilmiştir. Fakat, sonuç olarak; su altında birleştirilen plakadan elde edilen değerlerin AWS A5.35 standardına göre Seviye 1 kalitesinin gereksinimlerini karşıladığı görülmüştür.Öğe The effect of heat input in multi-pass GMAW of S960QL UHSS based on weaving and stringer bead procedure on microstructure and mechanical properties of HAZ(IOP Publishing Ltd, 2023) Mert, Tolga; Gürol, Uğur; Tümer, MustafaQuenched and tempered S960QL (yield strength & GE; 960 MPa) ultra-high strength steel (UHSS) thick plates were joined by multi-pass robotic gas metal arc welding (GMAW) using weaving and stringer bead techniques. The effects of microstructural changes in heat-affected zone (HAZ) of the joint on toughness and hardness were examined. Weaving and stringer bead techniques applied for the multi-pass welding procedure altered average peak temperatures and exposure time to those temperatures. Mechanical properties of HAZs were evaluated by utilizing notch impact and hardness tests, and these results were correlated with microstructural characterizations using optical (OM) and scanning electron microscopes (SEM). Prior austenite grain (PAG) coarsening occurred because of increased exposure time to peak temperature in coarse-grained HAZ (CGHAZ) of the W-5 (weaving pass) joint. CGHAZs at the face pass, which have not been subjected to a second thermal cycle, have the highest hardness in both joints. Hardness of SCHAZ and CGHAZ of S-12 joint was 7% and 1% higher compared with W-5 joint, respectively. Weld metal hardness of W-5 joint was 15% lower than that of S-12 joint. Both joints not only fulfilled the requirements of minimum 50 J per EN ISO 10025-6 at -20 & DEG;C but exceeded this limit by 50% (W-5) and 200% (S-12). Lateral expansions for impact toughness specimens were around 17.5% for S-12 joint, whereas it was 4% for W-5 joint. Since HAZ in the S-12 (stringer bead) joint is narrow compared with the one in the W-5 joint, impact toughness values were higher with the S-12 joint due to the locations of the notches of the impact specimens.Öğe A comparative study on the microstructure, mechanical properties, wear and corrosion behaviors of SS 316 austenitic stainless steels manufactured by casting and WAAM technologies(Elsevier, 2023) Gürol, Uğur; Kocaman, Engin; Dilibal, Savaş; Koçak, MustafaReplacing the traditional casting method with wire arc additive manufacturing (WAAM) to produce complex shaped parts will lead to using cost-effective technology even for challenging engineering applications depending on their geometry and number of the parts to be produced. This work performed a comparative study on the stainless steel 316 parts manufactured by WAAM and sand casting to reveal the microstructural, mechanical, wear, and corrosion behaviors. The WAAM components were manufactured using three different cooling dwell times and compared in terms of microstructures with the as-cast and heat-treated cast parts to reveal the properties of the WAAM parts. It was concluded that WAAM is a viable engineering alternative to the casting technology. Results showed that the WAAM and cast parts revealed similar microstructures, including delta ferrite and austenite phases, but the cast parts had a coarser grain and lower amount of delta ferrite due to slower cooling during the solidification. The yield and tensile strength of WAAM parts showed an increasing trend with the increase in dwell time, and on average, their yield strength was similar to 1.5 times higher than in cast parts due to the smaller grains and more elevated delta-ferrite content resulting from rapid cooling. Furthermore, the greatest wear resistance was obtained in the cast parts after solution annealing heat treatment followed by water quenching. In contrast the highest corrosion resistance was obtained from WAAM parts produced using a dwell time of 120 sec. In conclusion, WAAM technology can be an excellent alternative to casting technology for producing stainless-steel parts with optimized process parameters.Öğe Investigation into the influence of boronizing on the wear behavior of additively manufactured Inconel 625 alloy at elevated temperature(Springernature, 2023) Günen, Ali; Gürol, Uğur; Koçak, Mustafa; Cam, GürelDirected energy deposition (DED) technology is a cost-effective additive manufacturing method widely used in the production of complex-shaped parts made of various engineering alloys as well as superalloys due to its advantages such as high deposition efficiency, low-cost and flexible production possibilities. However, in addition to the low surface hardness found in wrought superalloys, the very high heat input and severe elemental segregation during the manufacture of superalloys by DED often result in diminishing of wear performance further. In this study, a simultaneous heat treatment and boronizing (980 degrees C 1 h) was applied to Inconel 625 part produced by the GMAW-based DED process in a single process in order to improve its microstructure and its tribological properties. The effects of boronizing applied after the DED process on the microstructure, some mechanical properties and wear behavior (both at room temperature and 500 degrees C) were investigated.Öğe Welding of high manganese austenitic cast steels using stainless steel covered electrode(Springer - International Publisher AG, 2023) Gürol, UğurIn this study, the characterization of production welds for high manganese steel castings exposed to little or no wear and moderate stresses, using the ER 307 stainless steel covered electrode, was investigated. The macro- and microstructural examinations were performed by means of stereo microscopy, optical microscopy, scanning electron microscopy and energy-dispersive spectrometry (EDS) to differentiate weld metal, partially melted zone (PMZ), heat-affected zone (HAZ), and base material (BM). Transverse micro-hardness test, Charpy impact tests and ultimate tensile tests were performed to evaluate the mechanical properties of the joints. The chemical analysis and elemental mapping were utilized to analyze the joint cross section in percentage weight with both optical emission spectrometer and X-ray spectrometer. The results indicated that the reduction in dilution from root to face regions led to an increase in the amount of delta ferrite contents through the weld passes from the root to the face. Moreover, the liquation cracks occurred due to the combination of eutectic phase formation, low thermal conductivity, and the large freezing range of the base metal. These cracks originated at the PMZ and propagated from the PMZ through HAZ to BM and lowered the tensile strength, % elongation and toughness of the weld joint by about 6 %, 27 % and 33.5 %, respectively.Öğe Casting properties of ASTM A128 Gr. E1 steel modified with Mn-alloying and titanium ladle treatment(Springer Singapore Pte Ltd, 2021) Gürol, Uğur; Karadeniz, Erdal; Çoban, Ozan; Kurnaz, Süleyman CanThis work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr. E1 steel (1.0C-13Mn) that is mostly used in the mining industry. The 1.0C-17Mn-xTi alloys (x=0, 0.05 and 0.1, in wt.%) were prepared. A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys. Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti. Correspondingly, after solution annealed, optimized titanium content (0.05wt.%) results in significant improvements in wear resistance, hardness, elongation, yield and tensile strengths by 44%, 31%, 30%, 8% and 12%, respectively, except 9% decrease in impact toughness compared to ASTM A 128 Gr. E1 steel without modification. These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.Öğe Characterization of armour steel welds using austenitic and ferritic filler metals(Springer India, 2022) Gürol, Uğur; Karahan, Tuba; Erdöl, Sevim; Çoban, Ozan; Baykal, Hakan; Koçak, MustafaIn this study, fillet welding processes were performed on high strength Miilux Protection 500 (MIL-A-46100) steel, which is used as armour material in defence industry, using GMAW method with austenitic ER307 and ferritic ER110S-G filler metals. The characterization of welded structure was carried out by performing elemental mapping processes as well as microstructural examination and microhardness tests. Results showed that hardness of weld metal was found to be 46% and 78% of the base metal hardness for austenic and ferritic filler metal, respectively. The fine-grained heat-affected zone was found to be the highest hardness while intercrital heat-affected zone was found to be lowest hardness through heat-affected zone. The smoother decrease was obtained in the softening zone with austenitic filler metal due to lower thermal conductivity. Consequently, the hardness values at a distance of 6 mm from the plate edge for both filler metals reached the hardness of base metal and both welded structures met the minimum requirements of the military standards.Öğe Fabrication and characterization of wire arc additively manufactured ferritic-austenitic bimetallic structure(Korean Institute Metals Materials, 2023) Gürol, Uğur; Turgut, Batuhan; Kumek, Hülya; Dilibal, Savaş; Koçak, MustafaBimetallic parts are used in many industrial fields, such as pressure vessels, shipbuilding, aerospace, and automotive industries. Conventional bimetallic part production involves a combination of two different metals that are joined using welding and brazing operations. Additive manufacturing technologies offer a cost-effective and innovative manufacturing alternative for complex 3D-shaped parts that can have multi-material designs for better structural performance. However, the structural performance of bimetallic components is primarily influenced by the combination of the employed materials, the interface's morphology, and interface bonding strength. This work investigated the microstructure and mechanical behavior of a bimetallic thick-walled structure as WAAM Wall fabricated by depositing low-alloyed metal-cored wire on the top of 316L stainless steel by robotic wire arc additive manufacturing (WAAM) process. The results showed that both low-carbon steel and austenitic stainless steel SS316L wires are suitable for manufacturing defect-free bimetallic WAAM components, which may widen the design flexibility to manufacture bi-metallic and or functionally graded WAAM components. However, detailed microstructural characterization indicated that martensitic microstructure containing chrome carbides was developed at the bimetallic interface due to an increase in Ni and Cr contents, resulting in a sudden increase of 95% in hardness and a sharp decrease of 70% in fracture toughness at the interface region compared to the SS 316L side. This high-hardness region also resulted in an increase of about 113% and 86% for yield and tensile strengths and a sharp reduction of 69% for elongation values in horizontal interface specimens compared to vertical interface specimens.Öğe Characterization of fillet welded armor steel performed by robotic gas metal arc welding: effect of heat input on microstructure and microhardness(Springer, 2025) Çoban, Ozan; Kaymak, Fatih; Gürol, Uğur; Koçak, MustafaIn this research, fillet welding was conducted on 8-mm thick Miilux OY Protection 600 (MIL-A-46100) armor steel using AWS A5.9 GeKa ER307 austenitic filler wire. The welding process involved robotic MIG/MAG with five different heat inputs ranging from 0.3 to 1.2 kJ/mm. The study focused on examining the influence of heat input on the microstructure, elemental changes, microhardness, and dimensions of the weld metal and the heat-affected zone (HAZ). These investigations were conducted to determine the welding parameters that they satisfy the quality requirements of the MIL-STD-1185 standard for this steel grade and weld consumable. Through analysis of macrostructure, microstructure, and microhardness, it was observed that increasing the heat input led to a decrease in hardness for both the weld metal and the HAZ, while expanding the HAZ width. The weld metal exhibited a homogenous hardness distribution at lower and higher heat inputs, but hardness increased from the root to the face for both heat inputs of 0.5 and 0.7 kJ/mm welds. Notably, a significant decrease in hardness occurred in the transition of partial transformation region (intercritical HAZ) and tempering region (subcritical HAZ) for heat inputs above 0.7 kJ/mm, indicating softening. Moreover, the width of the subcritical heat-affected zone substantially increased. Evaluation of the distance required to reach base metal hardness from the welding toe revealed that a heat input of 1.2 kJ/mm exceeded the maximum requirement of 15.9 mm according to the MIL-STD-1185 standard. However, the requirements of the military standard were satisfied for other heat input values. These findings were associated with microstructural changes in grain size, martensite, bainite, martensite/austenite morphology and their fractions, as well as delta ferrite morphology. The results successfully demonstrated that robotic GMAW welding can be applied using lower strength (undermatched) filler metal to satisfy the requirements of the respective standard of MIL-STD-1185.Öğe Effect of interlayer dwell time on output quality in wire arc additive manufacturing of low carbon low alloy steel components(Springer London Ltd, 2023) Turgut, Batuhan; Gürol, Uğur; Önler, RecepWire arc additive manufacturing (WAAM) has gained significant attention over the past decade due to its advantages, such as high productivity, cost-effectiveness, and ease of application. However, predictable WAAM of components with designed properties is still challenging due to the lack of comprehensive understanding of the process that uses considerable heat input. The interlayer dwell time is a critical process parameter in WAAM that impacts the thermal history of the manufacturing part, thereby controlling the output quality. This experimental study investigates the effect of interlayer dwell time on the microstructure and mechanical properties of low carbon low alloy steel components fabricated by WAAM. Three samples were produced by WAAM using identical process conditions by employing continuous deposition, 60 s, and 120 s dwelling after each layer deposition, respectively. The temperature profiles on both the substrate and the interlayer, hardness, yield strength, and microstructure variation were comparatively investigated. It was shown that the interlayer dwell time can significantly allow controlling the temperature fields experienced in the part, in turn, both mechanical and microstructural properties are modified. In addition, since the distance to the substrate increases with increasing built height, the thermal history and local properties of the specimens were found to be affected. Thus, a constant interlayer dwell time does not provide identical interlayer temperatures. It was found that compared to the samples without interlayer dwell time the samples with 120 s dwell time showed around 18% and 10% increased average hardness and average yield strength, respectively.
