Search

Lazerler gelişiminden bu yana günlük hayatımızı kolaylaştırarak günümüz teknolojisindeki ilerlemede büyük bir etkiye sahip olmuştur. İmalat sanayi lazer teknolojisinden en büyük payı almış ve birçok imalat uygulamasında tercih edilen bir teknoloji haline gelmiştir. Lazerle neredeyse bütün malzeme türüne işlem yapılabilmekte ve lazer teknolojisi endüstride markalama, kazıma ve kesme işlemlerinde yaygın olarak kullanılmaktadır. Bu çalışma markalama, kazıma ve kesme uygulamaları için düşük bütçeli bir CO2 lazer makinesinin tasarlanmasını ve üretilmesini ele almıştır. Makinenin rezonatör, optik hareket, kesim kafası ve kontrol sistemleri dahil olmak üzere tüm ana bileşenleri, ilgili okuyucuların benzer bir sistemi uygulaması için etraflıca açıklanmıştır. Makinede bulunan rezonatör, ticari olarak mevcut benzer sistemlere kıyasla ekonomik ve uzun servis ömrüne büyük bir fayda sağlayan tekrarlı gaz dolumuna izin verecek şekilde tasarlanmış ve üretilmiştir. Üretilen makine, ilk malzeme listesinden ve ilgili üretim sürecinden kauçuk, ahşap ve plastik malzemeler için yukarıda bahsedilen son uygulama örneklerine kadar açıklanmıştır. Lazer makine sistemi şu anda Karabük Üniversitesi imalat mühendisliği bölümünde kuruludur ve lisans eğitimi ve öğretimi için kullanılmaktadır. Ayrıca makine reklam, hobi, orman ürünleri, tekstil, deri ve küçük ölçekli mühendislik işlerinde orta ölçekli işletmelerin kullanımı için yeterli kapasiteye sahiptir., Since its early development, lasers had big impact in today’s technology advancement by facilitating our daily life. The manufacturing industry has taken the largest share of laser technology, and it has become a preferred technology in many manufacturing applications. Almost all material types can be processed with the laser and laser technology is widely used in industry for marking, engraving, and cutting processes. This article discusses designing and manufacturing of a low-budget CO2 laser machine, for marking, engraving, and cutting applications. All major components of the machine including resonator, optical train, cutting head and control systems have been discussed in detail for interested readers to implement a similar system. The resonator on the machine was designed and manufactured to allow repeated gas filling which is a major benefit for economical and extended service life as compared to similar commercially available systems. The machine has been described from initial material list and manufacturing process involved, all the way to the final aforementioned application examples for rubber, wood, and plastic materials. The laser machine system is currently installed in Karabuk Univesity’s manufacturing engineering department and used for undergraduate teaching and learning. Furthermore, it is sufficient capacity for use in medium-sized operations in advertising, hobby, forest products, textile, leather, and small-scale engineering works.

The aim of this study is to investigate the joinability of titanium pipes with laser beam welding. Welding processes were carried out in three different laser beam power (130, 140 and 160 W). Filler metal was used and during welding, the pipe was rotated at constant speed and the torch was positioned in horizontal position. In order to determine the welding quality and mechanical properties of the titanium pipes which were subjected to joining process, visual inspection, tensile test and hardness test were performed. In addition, microstructural investigations of the weld zone and SEM (EDS) image analyses were performed to determine the defects in the microstructure. As a result of tensile tests on welded samples, fracture was formed on the welding metal on the samples which were joined at low laser power, whereas at welded sample joined at high laser power, fracture occurs in outside the weld zone. As a result of the hardness tests on the welded samples, the highest hardness values were taken from the weld metal and the lowest hardness values were taken from the base material., Bu çalışmanın amacı titanyum boruların lazer kaynak yöntemi ile birleştirilebilirliğinin araştırılmasıdır. Kaynak işlemleri üç farklı lazer ışın gücünde (130, 140 ve 160 W) gerçekleştirilmiştir. Kaynak işlemleri esnasında ilave metal kullanılmış ve boru sabit hızda döndürülerek, torç yatay pozisyonda konumlandırılmıştır. Birleştirme işlemi yapılan titanyum borulara kaynak işlemi sonunda kaynak kalitesini ve mekanik özelliklerini belirlemek amacıyla, gözle muayene, çekme testi ve sertlik testi yapılmıştır. Ayrıca içyapıdaki kusurların belirlenmesi için kaynak bölgesinin mikroyapı incelemeleri ile SEM (EDS) çalışmaları yapılmıştır. Çekme testleri sonucunda, düşük lazer gücünde birleştirilen numunelerde kopma kaynak metalinden gerçekleşirken, yüksek lazer gücünde birleştirilen kaynaklı numunede kopma kaynak bölgesi dışından gerçekleşmiştir. Kaynaklı numunelere yapılan sertlik testleri sonucunda en yüksek sertlik değerlerinin kaynak metalinde, en düşük sertlik değerleri ise ana malzemede olduğu tespit edilmiştir.

In this study, duplex stainless (AISI2205) steel and pressure vessel (P355GH) steel have been joined by submerged arc welding method (SAW). Three different joining operations (AISI2205-AISI2205), (P355GH-P355GH) and (AISI2205-P355GH) were performed respectively. ELOX UP 309 L submerged arc welding wire and Eliflux Bss-A submerged arc welding powder were used for joining materials. Welded materials have been tested with eye, magnetic particle and radiographic examination methods were used to detect surface and subsurface defects. Tensile, bending, Charpy impact notch and hardness tests were then performed to determine the mechanical properties of welded samples. Additionally, microstructure investigations were made to determine the structural changes in the welding zone. Various NDE technqiues were adopted to investigate the quality of the welds. As a result of tensile tests, the rupture was made of welding metal in AISI2205-AISI2205 joints and P355GH in other joints was made of base material. No visible errors were observed in the welding area after bending test. When the V-notch impact energies of the materials were compared, the highest toughness value was measured in the ITAB of AISI2205 material and the lowest toughness value was measured in the P355GH weld metal. In hardness measurements, the highest hardness value was obtained in the HAZ of the AISI2205 material, whereas the lowest hardness was measured in the P355GH base material. Microstructure studies indicated that the weld metal comprised a dendritic structure, and the grains were observed to become coarse in the region adjacent to the melting boundary on the main material side.

Grade AH36 ship steel plate, frequently used in offshore applications, was joined underwater by shielded metal arc welding (SMAW) using two different types of electrodes (E6013 and E7014). The ship steel plate was also joined under atmospheric conditions in order to compare both joints in terms of mechanical and metallurgical properties. The E6013 rutile electrode was isolated by wrapping before use, and the underwater welding process was carried out at a depth of 8 m under the sea. The joints were first subjected to visual inspection and then liquid penetrant, ultrasonic, and radiographic tests were performed. In order to determine the mechanical properties of the joints, tensile, bending, and impact toughness tests were also carried out. In addition to the microhardness test on the weld zones, microstructural examination was also performed on the joints. As a result of the nondestructive tests, weld defects like slag remaining between the passes, gas porosities, burn-through, and lack of penetration were seen on the joints welded underwater with the two different electrodes. The study determined that these defects had significantly influenced the mechanical properties and width of the weld zone of the joints.

WOS: 000514814600011, The use of aluminum alloys in industry have been increased in due to their excellent low weight, corrosion resistance also other good features. Different aluminum alloys are joined with together when need of a structure presents different physical or mechanical properties with together. in this study, different aluminum alloys AA5754 and AA6013 joined by GMAW (gas metal arc welding) method under different welding parameters. After that, three-point bending test was carried out and notch impact test was performed to determine toughness behavior of the joints. in addition, the weld zone is characterized with hardness test and microstructure studies. While the welded samples joined with convenient parameters were bended 180 degrees, the cracks and fractures were occurred on the fusion line boundary of some samples due to unsuitable parameters. According to impact toughness test results, the highest toughness value was obtained from the HAZ (Heat affected zone) of AA5754. Besides, toughness values evaluated from the HAZ of AA6013 on the joints and weld metal were nearly same. With respect to hardness test results, the maximum hardness value was measured at the HAZ of AA6013 and this was followed by the weld metal and the HAZ of AA5754 sequentially. From the point of microstructure inspections, structures of all the weld metals were dendritic.

The use of aluminum alloys to reduce weight in air, sea, and land vehicles is increasing rapidly, especially due to their low density, excellent corrosion resistance, good forming properties, and increasable mechanical properties. A common aspect of all the relevant industrial sectors is the need to join the many parts of manufactured technological products using welding methods. In these industries, using welding to join different aluminum alloys having high mechanical properties is especially important. However, despite the widespread usage areas, it is very difficult to join different aluminums and their alloys via welding. In this study, AA5754/AA6013 aluminum alloys were joined using automatic gas metal arc welding (GMAW). Welded joints were created at two different welding speeds (150 and 180 mm/min) and three different welding current values (130, 140, and 150 A). This study investigated the microstructural and mechanical properties of AA5754/AA6013 aluminum alloy sheets joined at different welding speeds and current values. The macro and microstructures of samples taken from the welded joints were examined. In addition, hardness, tensile, bending, and fatigue tests were performed on the welded samples. The findings obtained as a result of the tests were evaluated and interpreted in light of the literature. Karabuk University Scientific Research Project CommitteeKarabuk University [KBUBAP-17-DR-406] The authors would like to thank the Karabuk University Scientific Research Project Committee for providing funding for this study (Project No. KBUBAP-17-DR-406) . WOS:000691196000005 2-s2.0-85112379090

Grade A ship-building steel-AISI 2304 duplex stainless steel composite plates were manufactured via explosive welding. The AISI 2304 plates were used to clad the Grade A plates. Optical microscopy studies were conducted on the joining interface for characterization of the manufactured composite plates. Notch impact, tensile-shear, microhardness, bending and twisting tests were carried out to determine the mechanical properties of the composites. In addition, the surfaces of fractured samples were examined by scanning electron microscopy (SEM), and neutral salt spray (NSS) and potentiodynamic polarization tests were performed to examine corrosion behavior. Near the explosion zone, the interface was completely flat, but became wavy as the distance from the explosion zone increased. The notch impact tests indicated that the impact strength of the composites decreased with increasing distance from the explosion zone. The SEM studies detected brittle behavior below the impact transition temperature and ductile behavior above this temperature. Microhardness tests revealed that the hardness values increased with increasing distance from the explosion zone and mechanical tests showed that no visible cracking or separation had occurred on the joining interface. The NSS and potentiodynamic polarization tests determined that the AISI 2304 exhibited higher corrosion resistance than the Grade A steel.

In this study, AISI 2304 duplex stainless steel sheets were joined with AISI 430 ferritic stainless steel sheets via resistance spot welding using various welding parameters. Welding processes were carried out at electrode forces of 0.6 and 0.8 MPa, welding currents of 2 and 3 kA, and welding times of 10, 20, and 30 cycles, and the effects of the welding parameters on the welded joints were investigated. In order to determine the strength of the welded zones, tensile-shearing tests were applied. The weld nugget diameters were measured using a digital caliper, while a micrometer was used to measure the electrode penetration depth values. In addition, hardness tests and scanning electron microscopy (SEM) studies were done on the welded regions of the joined samples. From the measured weld nugget diameters and electrode penetration depth values, it was determined that the changes in the welding parameters affected the weld nugget diameter and electrode penetration depth. The results of the tensile-shearing experiments showed that the increases in the welding parameters were effective on the tensile-shearing strength and weld nugget rupture form. Increasing the welding parameters also resulted in increased weld zone hardness. The microstructural examination indicated in particular that the increases in the welding parameters caused the ferrite grains to grow due to the rise in heat input.

Bu calismada farkli kimyasal bilesime ve mekanik ozelliklere sahip, dusuk karbonlu celik (S235JR) ile ferritik paslanmaz (AISI 430) celik malzemeler MIG kaynak yontemi ile farkli tel ilerleme hizlarinda (kaynak akimi) birlestirilmislerdir. Kaynak uygulamasi gerceklestirilmis kaynakli birlestirmenin mekanik ozelliklerini belirlemek icin kaynakli baglantilara cekme deneyi yapilmis, ayrica kaynak bolgesinde sertlik olcumleri gerceklestirilmistir. Son olarak kaynak metalinde meydana gelen olusumlar ve ITAB’daki degisimleri belirlemek icinde mikroyapi calismalari yapilmistir.

Bu çalışmada, 3 mm kalınlıkta paslanmaz çelik ve düşük karbonlu çelik levhalar; MIG kaynak yöntemi ile farklı parametreler kullanarak birleştirilmiştir. Birleştirilen numunelere çekme, eğme, çentik darbe testleri uygulanmış ayrıca mikrosertlik ve mikroyapı özellikleri incelenmiştir. Çekme testleri sonucunda; malzemelerin kaynak metali veya ısı tesiri altında kalan bölgeden (ITAB) ayrılmadığı, kopmanın düşük karbonlu çelik malzemede meydana geldiği tespit edilmiştir. Eğme testlerinde; kaynaklı numuneler 180˚ eğildiklerinde gözle görülebilir bir kaynak hatasına rastlanılmamıştır. Çentik darbe testlerinde, kaynak metali darbe tokluğu ITAB’lardan daha yüksek ölçülmüştür. Mikrosertlik testleri sonucunda en yüksek sertlik değeri kaynak metalinde ölçülmüştür. Mikroyapı incelemelerinde ısı girdisine bağlı olarak, paslanmaz çelik ve düşük karbonlu çeliğin ITAB bölgesinde tane irileşmesinin meydana geldiği tespit edilmiştir.

WOS: 000490124400003 Aluminum alloys exhibit good strength, excellent corrosion resistance and good forming properties along with low specific density. Due to these superior properties, they are widely used in the automotive, chemical, and food industries, especially in shipbuilding and the yacht industry. It is important to join these alloys used in the mentioned industrial areas. However, it is very difficult to join Al and its alloys via traditional welding methods despite its widespread use. In this study, 5754-H111 and 6013-T6 aluminum alloys were joined by friction stir welding. Welding operations were carried out at 1250 rpm using welding feed rates of 12.5, 25, and 32 mm x min(-1). Metallographic investigations were carried out to determine the microstructural and macrostructural properties of the weld zones. Tensile, bending, and hardness tests were also performed to determine the mechanical properties of the welded samples. The results obtained as a result of the tests were evaluated and interpreted. Micro-void defects were found to occur in the weld metal-HAZ transition zones. It was established that the welding speed affected the tensile strength. The highest tensile strength was obtained at a feed rate of 25 mm x min(-1). It was determined that no cracking or fraction occurred in the welded samples as a result of the bending test. Karabuk UniversityKarabuk University [KBUBAP-17-DR-406] The authors would like to thank the Karabuk University Scientific Research Project Committee for the provision of funding for KBUBAP-17-DR-406.

Bu çalışmada, Grade A gemi sacı,örtülü elektrodla ark kaynak yöntemi ile, parafin kaplanmış E 6013 standardınasahip rutil örtü tipli elektrodla, atmosferik şartlarda ve su altında farklıderinliklerde birleştirilmiştir. Kaynaklı birleştirmelerin mekaniközelliklerini belirlemek için sertlik deneyi ve çekme testleri yapılmıştır.Ayrıca kaynak bölgesinde meydana gelen yapısal değişim ve dönüşümlerigözlemlemek için kaynaklı numuneler üzerinde mikroyapı çalışmalarıgerçekleştirilmiştir. Yapılan sertlik testleri sonucunda, en yüksek sertlikdeğerleri kaynak metalinden ölçülürken onu sırasıyla ısının tesiri altındakalan bölge (ITAB) ve ana malzeme takip etmektedir. Yapılan çekme testlerisonucunda, tüm numunelerde kopma kaynak metalinde gerçekleşmiş ve bütünbağlantı dayanımları, ana malzemeden düşük bulunmuştur. Mikroyapıincelemelerinde ilk pasoların ince taneli izotrop, dış kapakları oluşturan sonpasoların ise ince sütunsal taneli olduğu gözlenmiştir. Ayrıca su altındabirleştirilen numunelerde hızlı soğumadan kaynaklı martenzitik dönüşüm olduğumikroyapı incelemelerinde gözlenmiştir. Deney sonuçları genel olarakdeğerlendirildiğinde, sualtı ark kaynak yöntemiyle birleştirilen numunelerinatmosferik şartlarda birleştirilen numuneye göre uzama değerlerinde yaklaşık %30, çekmede ise yaklaşık % 12 daha düşük dayanım sergilediklerigözlemlenmiştir.&nbsp, In this study, Grade A ship steel was joined at both the atmosphericconditions and underwater at various depths through shielded metal arc weldingmethod using paraffin coated shielded rutile type electrode conforming to E6013 standard. In order to determine the mechanical properties of welded jointshardness and tensile tests were carried out. In addition, microstructuralexaminations were performed on the welded specimens in order to observestructural the changes and transformations occurring in the welding zone. Thehardness test results showed that the highest hardness values are seen for theweld metal and these are followed by heat affected zone (HAZ) and basematerial. After the tensile tests, it was seen that all the specimens fracturedat the meld metal and that strength of the joints lower than that of basematerial. It was observed from the microstructural examinations that firstpasses are fine grained isotropic while the last passes are fine grainedcolumnar. In addition, martensitic transformation due to rapid cooling was seenin the specimens joined at underwater. When the experimental results aregenerally evaluated, it is seen that the specimens joined through underwaterarc welding method exhibited 30 % lower elongation and 12 % lower tensilestrength than those joined at the atmospheric conditions.

In this study the repair-maintenance welding process performed with MAG welding method by a MIG-MAG welding equipment mounted on the 3D printing machine. For this aim an assumed broken machine gear was used. The CAD model of the broken gear designed and cut by laser cutting machine. Then the broken gear fixed exactly on the 3D metal printer. There is an important difference between accumulation of metals and accumulation of plastic materials. Operating temperature of plastics are between 190-200°C although metals are about between 3000-4000°C. Thus, it is inevitable that high operating temperatures effect adversely working of the 3D metal printer used in this study. For this reason, to deposite metal materials, important revisions applied on the 3D metal printer. Depositing process of the broken gear areas carried out four passes by MAG welding equipment (two are bottom side and other two are top side of the part)., Buçalışmada; MIG-MAG kaynak ünitesi, 3B metal yazıcıya monte edilerek MAG kaynakyöntemi ile bir tamir-onarım kaynak işlemi gerçekleştirilmiştir. Bu amaç içinkırılmış kabul edilen bir makine dişlisi kullanılmıştır. Kırılmış dişlinintasarımı bilgisayar destekli ortamda tasarlanıp lazer kesme işlemi ileüretilmiştir. Daha sonra kırık olan dişli parçaları hassas bir şekilde 3B metalyazıcının tablasına sabitlenmiştir. 3B yazıcıyla metal malzeme ve plastikmalzeme biriktirme işlemleri arasında önemli bir fark bulunmaktadır. 3Byazıcılarda plastik malzeme kullanıldığında çalışma sıcaklığı yaklaşık 190-200°C arasında iken metal malzeme ergitilirken çalışma sıcaklığı yaklaşık3000-4000 °C’ye ulaşır. Bu çalışma sıcaklığının çok yüksek olması 3 boyutlumetal yazıcının çalışmasını olumsuz yönde etkilemektedir. Bu nedenle çalışmadametal doldurma işlemini gerçekleştirmek için 3 boyutlu metal yazıcıda önemliuyarlamalar yapılmıştır. Kırık dişli parçalarının tamir edilecek bölgesinidoldurma işlemi MAG kaynağı ile ilk ikisi parçanın üst tarafından diğer ikisiise alt tarafından olacak şekilde dört pasoda gerçekleştirilmiştir

Bu çalışmada, sementasyon işlemi görmüş AISI 8620 çelik malzemenin aşınan yüzeyleri farklı kimyasal içeriğe sahip tozlarla, plazma püskürtme yöntemiyle kaplanarak tekrar kullanıma uygun hale getirilmesi amaçlanmıştır. Kaplamaların servis şartlarındaki aşınma dayanımlarını belirlemek için aşınma testi, kaplama tabakası ve arayüzeylerin karakterizasyonu için sertlik testi yapılmıştır. Ayrıca kaplama numuneleri üzerinde arayüzey özelliklerini belirlemek için, taramalı elektron mikroskobu (SEM/EDS) çalışmaları gerçekleştirilmiştir. Yapılan sertlik ölçümleri sonucunda; en fazla yüzey sertliğine sahip kaplamanın 72F-NS kaplaması olduğu tespit edilmiştir. Aşınma testleri sonucunda en yüksek aşınma direnci CRC-106 kaplamasından elde edildiği ve onu sırasıyla 68 F-NS-1, 72F-NS AMDRY 962 takip ettiği bulunmuştur. SEM/EDS incelemeleri sonucunda kaplama tabakalarının lamelli olduğu ve kaplama tabakası ile arayüzeyde oksitlerin oluştuğu gözlenmiştir.

Bu çalışmada;düşük yoğunluk, yüksek dayanım ve mükemmel korozyon direncinden dolayı havacılık,uzay ve kimya endüstrilerinde oldukça yaygın olarak kullanılan ticari saf titanyum(Grade2) levhalar, nokta direnç kaynak yöntemi ile birleştirilmiştir. Birleştirmeişlemlerinde; farklı elektrod kuvveti (3 ve 6 kN), kaynak akımı(3,5 ve 7 kA) vekaynak süresi (10,20 ve 30 çevrim) kullanılarak, kaynak parametrelerininçekme-makaslama dayanımında etkisi incelenmiştir. Çekme-makaslama testisonuçları Taguchi metodunun en büyük-en iyi kontrol karakteristiği ile optimize edilmiştir.Maksimum çekme-makaslama dayanımı için belirlenen optimum test kombinasyonu, A2B3C3(6kN-7kA-30 çevrim) olarak belirlenmiştir. Çekme-makaslama dayanımısonuçlarına, kaynak parametrelerinin etkisi varyans analizi (ANOVA) metodu kullanılarakincelenmiş ve en etkin parametrenin %45.82 ile kaynak akımı olduğu tespit edilmiştir., In thisstudy, commercial titanium (Grade 2) plates, which are commonly used inaviation, space and chemistry industries because of its low density, highresistance and perfect corrosion resistance, are jointed by using spotresistance welding. In the process, the effect of welding parameters on tensilestrength using different electrode strengths (3 and 6 kN), welding current (3,5 and 7 kA) and welding time (10, 20 and 30 cycles). The results of tensilestrength test were optimized with the characteristic of maximum-best control ofTaguchi method. Optimum test combination for maximum tensile strength wasdesignated as A2B3C3 (6 kN-7 kA-30 cycles). Effects of welding parameters ontensile strength results were analyzedwith analysis of variant (ANOVA) method and the most effective parameter wasdetermined as welding current with %45.82.

Diffusion welding/bonding has been successfully used to joint dissimilar metals widely. In this study, pure Ti and AISI 430 ferritic stainless steel plates were joined through diffusion welding using a Ni interlayer at various temperatures (800, 825, 850 and 875 °C), holding times (15, 30, 60 and 120 min) and under a constant pressure (3 MPa) under argon shielding media. The welded joints were subjected to tensile-shear tests and hardness tests in order to determine their interfacial strength. In addition, microstructural properties of the joined interface were examined using optical and scanning electron microscope (SEM). The tensile-shear test results showed that the fractures occurred mostly in the interface of the Ni-ferritic stainless steel web at lower temperatures. It was seen from the hardness results that the highest hardness value was obtained for the titanium side and the hardness values increased with increasing welding temperature and holding time. SEM/EDS examinations showed that the diffused atoms and diffusion distance increased depending on the increasing temperature and holding time.

Explosive welding is a solid state welding process, which uses a controlled explosive detonation to force two metals together at high pressure. The process has been fully developed with large-scale applications in the manufacturing industry. The explosive bonding technique has an ability to bond a variety of similar and dissimilar materials, and has been applied to fabricate the clad materials and some composites such as multilayered and wire-reinforced materials. In this study, aluminum plates were explosively welded by placing a steel wire mesh between them in order to produce wire mesh reinforced composite materials. The steel wire meshes were placed at two different orientations (45 degrees and 90 degrees). The wire mesh was used to improve the mechanical properties of the explosively welded aluminum plates. Hardness, tensile strength, toughness, bending and microstructure of the explosively welded composite materials were evaluated. The tensile and toughness tests results showed that the 45 wire mesh reinforced composites exhibited higher strength than unreinforced explosively bonded Al plates. No separation was observed in the interface of the welded composite materials after three-point bending. The highest hardness value was measured for the area near the joining interface. (C) 2015 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved.

In this study, AISI 316L series austenitic stainless steel sheets were joined by tungsten inert gas welding method in continuous and pulsed currents. Regarding microstructural investigation and hardness values of weld metal, samples were welded to investigate the effect of current type on grain structures of weld metal. Results showed that samples welded by using pulsed current had considerable different properties compared to the samples welded by using continuous current. While the weld metals of joinings obtained by using continuous current displayed a coarse-grained and columnar structure, weld metals obtained by using pulsed current had a finer-grained structure. It was also found that hardness values of samples, which were welded with continuous and pulsed current, were quite different.

In this study, Grade A ship steel sheet (parent sheet) to AISI 316L austenitic stainless steel sheet (flyer sheet) used in offshore and ship building were cladded through explosive cladding at various explosive ratios. The effect of explosive ratio on the cladded joint interface was investigated. For this purpose, tensile-shear, impact toughness, bending, microhardness properties and microstructure of the explosively cladded joints were examined. Tensile-shearing tests results showed that shear and fracture took place in the AISI 316L sheet not in the joining interface. The impact toughness of the explosively cladded specimens at room temperatures was found significantly higher than that of parent sheet (Grade A) because of the high impact toughness of AISI 316L austenitic stainless steel layer. No separation was observed in the joint interface of the explosively cladded sheets after three-point bending. Hardness values of the explosively cladded joint increased with increasing explosive ratio and the highest hardness values were obtained near the interface. Microstructural examination showed that increasing explosive ratio transformed the cladding interface from smooth to wavy shape. Moreover, with increasing explosive ratio, the wavelength and amplitude of the waviness increased. It was also observed that grains near the interface were elongated parallel to the explosion direction. Consequently, mechanical properties of Grade A ship sheet can be increased by explosive cladding with AISI 316L austenitic stainless steel.

Sevim, Ibrahim/0000-0003-0582-4992; kaya, yakup/0000-0002-9951-2844 WOS: 000319557200056 In this article, Metal Inert Gas (MIG) weldability of commercially received and aged samples of 6061-T-6 and 7075-T-651 aluminum alloys was investigated. The welding joints were prepared in ten different combinations. Microstructure, microhardness, EDX, energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analyses were used in order to evaluate the effect of aged heat treatment on the performance of welded joints. In addition, the mechanical properties of welding joints were characterized using the tensile and microhardness tests. In conclusion, it was shown that prewelding aging heat treatment improves the mechanical properties of welding joints.

In the present study, Ti–6Al–4V alloy was bonded to electrolytic copper at various temperatures of 875, 890 and 900 °C and times of 15, 30 and 60 min through diffusion bonding. 3 MPa uniaxial load was applied during the diffusion bonding. Interface quality of the joints was assessed by microhardness and shear testing. Also, the bonding interfaces were analysed by means of optical microscopy, scanning electron microscopy and energy dispersive spectrometer. The bonding of Ti–6Al–4V to Cu was successfully achieved by diffusion bonding method. The maximum shear strength was found to be 2171 N for the specimen bonded at 890 °C for 60 min. The maximum hardness values were obtained from the area next to the interface in titanium side of the joint. The hardness values were found to decrease with increasing distance from the interface in titanium side while it remained constant in copper side. It was seen that the diffusion transition zone near the interface consists of various phases of βCu 4 Ti, Cu 2 Ti, Cu 3 Ti 2 , Cu 4 Ti 3 and CuTi.

In this study, austenitic stainless steel and copper materials were bonded through the diffusion welding method, one of the solid-state welding processes. The welding process was carried out at 875°C temperature for 30 minutes under 3 MPa pressure. Two different methods were employed in the welding process. In the first method, the conventional diffusion welding procedure was followed. In the second one, an external electrical current was applied to the parts to be joined with the help of a system that was added to the conventional system. By doing so, the aim was to determine the diffusion amount and length for the specimens obtained with and without current. The weld quality of the diffusion welded specimens was examined using the tensile and hardness test. In addition, microstructural analyses were done using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The highest hardness value was obtained in regions next to the interface and it was decreased gradually as the distance from the interface increased on both sides of the interface. The results indicated that the highest interface strength was obtained for the specimens joined when the external current was applied. According to the EDS and EDS line element analyses results, it can be seen that the specimens joined by applying the external current had a higher amount of diffusion and length than the specimens joined by the conventional technique.

In this study, commercially pure titanium sheets (American Society for Testing and Materials grade 2) were welded by resistance spot welding at various welding parameters. The welded joints were subjected to tensile-shearing tests in order to determine the strength values. In addition, the hardness and microstructural examinations were carried out in order to examine the influence of welding parameters on the welded joints. The experimental results showed that increasing electrode force, welding current and welding time increased the tensile-shearing strength of the welded specimens. Hardness measurement results indicated that welding nugget had the highest hardness and this was followed by the heat-affected zone and the base metal. Microstructural examinations showed the growth of the weld nugget grains with increasing heat input. Besides, due to plastic deformation during the welding process, twins were formed and at the same time twins increased with increasing electrode force, welding current and welding time.

Titanium and low carbon steel plates were joined through diffusion bonding using a silver interlayer at various temperatures for various diffusion times. In order to determine the strength of the resulting joints, tensile-shear tests and hardness tests were applied. Additionally, optical, scanning electron microscopy examinations and energy dispersive spectrometry elemental analyses were carried out to determine the interface properties of the joint. The work showed that the highest interface strength was obtained for the specimens joined at 850 °C for 90 min. It was seen from the hardness results that the highest hardness value was obtained for the interlayer material and the hardness values on the both sides of the interlayer decreased gradually as the distance from the joint increased. In energy dispersive spectrometry analyses, it was seen that the amount of silver in the interlayer decreased markedly depending on the temperature rise. In addition, increasing diffusion time also caused some slight decrease in the amount of silver.

In this study, commercially pure (CP) titanium sheets (ASTM Grade 2) were welded by resistance spot welding at different welding parameters and under different welding environments. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zones. In addition, hardness and microstructural examinations were carried out in order to examine the influence of welding parameters on the welded joints. The results showed that increasing current time and electrode force increased the tensile shearing strength and the joints obtained under the argon atmosphere gave better tensile-shearing strength. Hardness measurement results indicated that welding nugget gave the highest hardness and the heat affected zone (HAZ) and the base metal followed this. The argon gas used during the welding process was seen to have no influence on the hardness values. Microstructural examinations revealed that the deformations took place in the welding zone during welding. The twinning took place in the grains. High electrode force and high weld cycles, were used during the welding, increased the twinning. © 2005 Elsevier Ltd. All rights reserved.

In this study, Ti6Al4V alloy plates and commercial copper plates were bonded through explosive welding process. Different amounts of explosive material were used to investigate its influence on the bonding interface. Elbar-5 powders were used as explosive material and the bonding process was carried out through oblique geometry method. Microstructures of the bonded sections were examined and then tensile-shearing tests and hardness measurements were carried out on the bonded specimens. Tensile-shearing tests results showed that shear and fracture took place in the copper plates not in the joining interface. The highest hardness value was measured from the zone near the joining interface. Microstructural examination showed that with increasing explosive material amount the length and amplitude of the waviness in the interface were increased. SEM studies showed that no traces of intermetalics were observed in the interface. (c) 2005 Elsevier B.V. All rights reserved.

In this study, 304L stainless steel was bonded by MIG welding and mechanical and microstructural properties of the welded samples were investigated. Welding was carried out under different shielding media, which are argon and different additions of hydrogen in Ar. As current values, 140, 180 and 240 A were chosen for the welding current parameters. The sample that was welded under 1.5% H-2-Ar shielding media and with a welding current of 240A was found to be the best in terms of means of tensile strength. Impact tests revealed that toughness of the welding increases with increasing hydrogen amount in Ar and welding current. For all the welding parameters, hardness test results showed that base metal gave a higher hardness value than HAZ and weld metal. Welded samples were also characterized by means of bending test and microscopic investigations. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

The main purpose of thermal spraying method is to produce wear resistant surfaces. Easy applicability, very low possibility of metallurgical changes and low distortion of coated parts due to low heat transfer to the substrate and salvation of worn parts are some of the practical advantages of this process. In this study, abrasive wear behaviour of powder flame sprayed coatings on steel substrates has been investigated. Coating was carried out onto both hot and cold substrates by using four types of powders. Prior to the wear tests, the coated specimens were machined on a lathe and surface roughness and hardness measurements were carried out on the machined surfaces. Heating the substrates prior to the coating led to the decrease in the hardness of the coating layers. Abrasive wear resistance of flame sprayed coatings was seen to be dependent on the chemical composition and characteristics of coating materials and coating condition. (C) 2002 Elsevier Science Ltd. All rights reserved.

In this study, wear behaviour of crankshaft journals filled by a submerged arc welding with different welding wires and powders is investigated. Hardness and microstructure variations in the submerged arc welding are examined. In addition, the amount of weight loss in abrasion samples of filling dry and lubrication ambience is measured under 40 N loads. It is observed that the amount of abrasion decreased with the increase of hardness at a certain point. Thin wire structure is provided for better abrasion resistance, and abrasion decreases with lubrication. В работе исследован режим износа цапф коленчатого вала, обработанных дуговой сваркой под флюсом с различными сварочными проволоками и порошками. Изучены вариации твёрдости и микроструктуры при дуговой сварке под флюсом. Кроме того, была измерена величина потери веса в образцах, подвергнутых истиранию в сухих и смазочных средах при нагрузках в 40 Н. Наблюдалось уменьшение величины истирания с увеличением твёрдости до определённого предела. Было обеспечено использование тонкой проволоки для лучшего сопротивления истиранию, а истирание уменьшалось при смазке. В роботі досліджено режим спрацювання цапф колінчастого валу, оброблених дуговим зварюванням під флюсом з різними зварювальними дротами і порошками. Досліджено варіації твердості та мікроструктури при дуговому зварюванні під флюсом. Крім цього, було виміряно величину втрати ваги в зразках, підданих стиранню в сухих і змащувальних середовищах при навантаженнях у 40 Н. Спостерігалося зменшення величини стирання зі збільшенням твердості до певної границі. Було забезпечено використання тонкого дроту для кращого опору стиранню, а стирання зменшувалося при змащуванні.

In this study, X60, X65 and X70 steels used in petroleum and natural gas pipeline were joined with Submerged Arc Welding by using different type of welding fluxes (LN761 and P223) and wires (S1 and S2Mo). Initially, visual and radiographic inspection techniques were subjected to welded joints for determining surface and subsurface defects. After that, spectral analyses were carried out in order to determine the compositions of wire-flux-base metal on the joints. Impact toughness test were performed for determining toughness properties the joints. Furthermore, hardness and microstructure studies were also * Sorumlu Yazar / Corresponding Authorcarried out on the samples. As a result of the visual and radiographic inspection on the welded samples, there were no weld defects on joints were observed. It was clearly understood that carbon ratio in the compositions of weld metal higher than base metal but lower than filler metal in terms of spectral analyses results. According to impact toughness test results, the joints obtained by using S2Mo welding wire and P223 welding flux had better impact toughness value than the joints obtained by S1 welding wire and LN 761 welding flux. With respect to hardness test, the highest hardness values were measured on weld metal. When the microstructure images were examined, it is clearly understood that similar images for all the joints were shown adjacent zones to weld metals heat affected zones and welding boundary, due to heat input constant., In this study, X60, X65 and X70 steels used in petroleum and natural gas pipeline were joined with Submerged Arc Welding by using different type of welding fluxes (LN761 and P223) and wires (S1 and S2Mo). Initially, visual and radiographic inspection techniques were subjected to welded joints for determining surface and subsurface defects. After that, spectral analyses were carried out in order to determine the compositions of wire-flux-base metal on the joints. Impact toughness test were performed for determining toughness properties the joints. Furthermore, hardness and microstructure studies were also carried out on the samples. As a result of the visual and radiographic inspection on the welded samples, there were no weld defects on joints were observed. It was clearly understood that carbon ratio in the compositions of weld metal higher than base metal but lower than filler metal in terms of spectral analyses results. According to impact toughness test results, the joints obtained by using S2Mo welding wire and P223 welding flux had better impact toughness value than the joints obtained by S1 welding wire and LN 761 welding flux. With respect to hardness test, the highest hardness values were measured on weld metal. When the microstructure images were examined, it is clearly understood that similar images for all the joints were shown adjacent zones to weld metals heat affected zones and welding boundary, due to heat input constant.

In this study, Ti-6Al-4V and Al plates were joined by explosive welding at various explosive loads. Tensile-shear, bending, hardness, microstructure and corrosion behaviours of the explosively joined samples were investigated. At the end of the tensile-shear tests carried out according to ASTM D 3165-95 standard, no seperation was observed in the interfaces of the joined samples. The results of the bending tests also showed no sign of any distinctive seperation, crack and tear in the interfaces. The highest hardness values were measured in regions next to interfaces. The optical microscope and SEM examinations revealed that an increment in wavelength and amplitude was observed with increasing explosive load. It is seen from the corrosion test results that materials loss was high at the beginning of the corossion tests but the rate of material loss decreased later on. Furthermore, increasing deformation with increasing explosive load increased the materials loss in corrosion tests. © 2006 Elsevier Ltd. All rights reserved., 07/2002-07, We would like to thank to M.K.E Barutsan Company, Turkey for their kindly supplying the materials, equipment and staff. This work was financially supported under Gazi University Project (07/2002-07).

The purpose of this study is to produce composite plates through explosive welding process widely used in developed countries and is of great importance to produce such plates and unfortunately currently its use in our country is not common. In this study, stainless steel-titanium plates were joined explosively employing oblique geometry route at different explosive ratios. The bonding was investigated using optical and scanning electron microscopy and tensile-shearing, bending, hardness and corrosion tests were carried out. Optical and scanning electron microscopy examinations showed that a transition was observed from smooth bonding interface to a wavy one with increasing explosive ratio. It was also observed that grains near the interface were elongated parallel to the explosion direction. No shearing within the interface was seen from the tensile-shear tests and fracture took place within the low strength material. The bended specimens showed that defects such as separation and tearing were not observed. Hardness was increased with increasing explosive ratio and the highest hardness values were obtained near the bonding interface. Weight increase due to formation of a stable oxide layer on the welded stainless steel-titanium plates was seen from corrosion tests while weight loss was seen from the other specimens and this loss was increased with increasing explosive ratio. © 2005 Elsevier B.V. All rights reserved.

The submerged arc welding process is commonly used due to its easy applicability, high current density and its ability to deposit a large amount of weld metal using more than one wire at the same time, especially in restoration of worn parts, which is of great importance to manufacturers. In this study, worn parts were welded using the submerged arc welding process. Various wires and fluxes were used for this purpose. These welded parts were subjected to wear tests under different loads, and changes in the hardness and microstructures were examined. A pin-on-disk wear test apparatus was used. The results showed that the hardest weld metal showed the highest wear resistance, while the least hard weld metal showed the least wear resistance. The weld hardness and wear resistance obtained were found to be dependent on the chemical composition of the weld wire and flux. (C) 2003 Elsevier Science Ltd. All rights reserved.