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Lightweight magnesium (Mg) alloys are employed in a wide range of applications due to their high specific strengths. Nevertheless, some applications require improvement of the wear resistance of Mg alloys. The purpose of this study was to investigate the effect of the initial surface conditions, cold spray temperature, and coating material on the wear resistance of the cold sprayed coatings on WE43 Mg substrate. Blasted and sandpapered surfaces were coated with commercial powders of K-32 (Ni and Al2O3) and K-714 (Zn, Ni, and Al2O3). The coating materials were cold sprayed on blasted and sandpapered WE43 Mg surfaces at 500 °C and 600 °C. Surface roughness, thickness and wear resistance of the coatings were examined. Deposition efficiency was improved by raising the N2 gas temperature. The samples with the greatest wear resistance were those that were coated with Zn, Ni, and Al2O3 powder mixture on sandpapered surfaces at temperatures of 600 °C, where deposition efficiency is maximum. Cold spray coatings enhanced the wear resistance of the WE43 Mg substrate.

Toprak işleme makinaları sürüm işlemi yaparken, işleyici parçalar ile toprakta bulunan kuvars veya korundun gibi partiküller sürtünmektedir ve bu durum toprakta sürüm yapan işleyici tarım ekipmanlarında aşınmalara neden olmaktadır. Ülkemizde, bu ekipmanların mekanik özelliklerinin iyileştirilmesi ve aşınmaya karşı dirençlerini artırabilmek amacıyla uygulanan sertleştirme ısıl işlemleri gelişen teknikler ile birlikte değişmektedir. Yapılan çalışmada süneklik ve tokluk değerlerinin yüksek olduğu bilinen ve tarım aletlerinin belli bölümlerinde sıklıkla kullanılan 60SiMn5 alaşımına sertleştirme işleminden sonra farklı sıcaklıklarda (250 °C ve 270 °C) uygulanan menevişleme işlemlerinin mikroyapı ve mekanik özelliklerine etkileri incelenmiştir. Bu amaçla, 970 °C’ de östenitleştirme ve ardından yağda soğutma işlemi uygulandıktan sonra farklı sıcaklıklarda menevişleme işlemi uygulanmıştır. Uygulanan menevişleme işlemlerinin mikroyapıya etkisi optik mikroskop ve SEM-EDX analizleri ile gerçekleştirilmiştir. Numunelerin sertlik, darbe ve kuru kum kauçuk aşınma testleri gerçekleştirilmiştir. Çalışmanın sonucunda 270 °C’ de yapılan menevişleme işlemi ile numunede alt beynit yapısının daha homojen dağılmasının sağlaması sebebi ile malzemenin tokluk değerinde artış görülmüştür. Ayrıca uygulanan menevişleme işlemlerinin akma, çekme ve aşınma dayanımlarını arttırdığı ve mekanik özellikleri olumlu yönde etkilediği gözlemlenmiştir.

Synthesis of silicon oxide (SiO2) via the sol-gel method and SiO2 coating ability on to Ti6Al4V alloy were investigated, in the novel study. Ti6Al4V alloy is the most used alloy in biomedical applications due to its many advantages. However, it has a minor disadvantage like releasing ions into the human body. In this study, the substrate material Ti6Al4V alloy samples were coated using the sol-gel method with alkoxysilane solutions (tetraethyl orthosilicate, TEOS; Si(OC2H5)4 and glycidoxypropyltrimethoxysilane, GPTMS; C9H20O5Si) containing the unit of prepared Si(OR)n after the surface preparations were made. The prepared solutions were examined using thermal analysis methods and the process temperatures to be applied to the coatings were determined according to the results of the analysis. Coated samples were subjected to aging, drying, and sintering processes at specified temperatures. The morphologies and structures of the samples were investigated by using a scanning electron microscope with energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). The sol-gel coating ability of the silicon oxide on the surface of the Ti6Al4V alloys has been discussed. The results demonstrate that cracks were observed in coating produced by TEOS precursor whereas the coatings used GPTMS precursor exhibited crack-free surface independently of dipping number. The crack formation tended to reduce with increasing dipping number of coatings produced by TEOS precursor. Distances between coating islets gradually became smaller as the number of dippings increased, and the continuity of the coatings increased. It has been observed that SiO2 coating layers produced with GPTMS are obtained in a more continuous and crack-free form than the layers produced with TEOS.

Bu çalışmada biyomalzeme uygulamalarında kullanılmak üzere etkili bir biyomalzeme geliştirilmesi amaçlanmış ve sol-jel yöntemi kullanılarak Ti6Al4V altlık malzemeler üzerine hidroksiapatit kaplamalar yapılmıştır. Sol-jel yöntemi ile biyoaktifliği ve korozyon dayanımı yüksek, çatlaksız bir kaplama tabakası elde etmek amaçlanmıştır. Bu amaçla, hazırlanan hidroksiapatit çözeltilerine farklı oranlarda oksalik asit (OA, C2H2O4) eklenmiş ve OA’nın kaplama morfolojisinde oluşturduğu değişimler incelenmiştir. Analizlerde, enerji dispersif spektrumlu taramalı elektron mikroskobu (SEM-EDS) ve X-Işını kırınımı (XRD) kullanılmıştır. Kaplama yapılmış numunelerin korozyon özelliklerinde meydana gelen değişimler ise hazırlanan yapay vücut sıvısı içinde üç elektrotlu sistem kullanılarak gerçekleştirilen elektrokimyasal-potansiyodinamik korozyon testleri ile incelenmiştir. Çalışmanın sonucunda OA katkı oranının artması ile kaplama adacıkları arasındaki mesafelerin kapandığı, morfolojide gözlemlenen çatlakların azaldığı ve büyük ölçüde engellendiği gözlemlenmiştir. Korozyon hızları kıyaslandığında ise OA miktarının ağırlıkça % 0,001 olduğu ve 0,015 olduğu numunelerde korozyon hızının diğer katkılı numunelere göre 10 kat ve katkısız numuneye göre ise 5 kat daha az olduğu gözlemlenmiştir.

Aluminum metal matrix composites were used in various fields such as aircraft, underwater, automobile, aerospace. Several fabrication techniques were used for the production of these composites. Among the various methods, the powder metallurgy route provides dimensional accuracy and high production rates. In this paper, metal matrix composites that include 7075 aluminum alloy chips and Al2O3 particles were produced by using a hot pressing. The effect of reinforcement amount and T6 heat treatment on the mechanical and wear properties of the composites were investigated. Al2O3 particles were added by weight of 5, 10 and 15 % and the composites were produced by hot pressing. T6 heat treatment consisted of a solution treatment at 480?C for 2 h and artificially aging process at 120?C for 24 h. Wear resistance of the composites was determined by a ball-on-disc dry sliding wear test. Brinell Hardness of the composites tended to increase with the increasing Al2O3 reinforcement up to 10 wt.% and with T6 treating. Particle reinforcement improved the wear resistance up to 10 wt.% Al2O3. In addition, volumetric material loss tended to decrease after the aging process.

Cold metal transfer (CMT) welding is a brand-new arc welding technique which shows adequate results for welding of thin sheets and dissimilar materials. Corrosion behavior of dissimilar aluminum joints should be determined in terms of predicting the effect of welding process on the possible failures in their constructions caused by corrosive agents. The present study investigates the effect of heat input on mechanical properties and corrosion rate of AA5754-AA7075 joints welded by CMT using ER5356 filler wire. Pore formation was observed not only in the weld metal but also in the partially melted zone of AA7075 base metal due to the vaporization of zinc. Increased heat input caused over aging and zinc vaporization in AA7075 base metal, and grain coarsening in AA5754 base metal consequently decreased the tensile strength. The average tensile strength of AA7075-AA5754 joints varies between 235 and 240 MPa. The ductile fracture occurred at the AA5754 base metal side in all samples. Pitting was observed as the dominant corrosion mechanism. Corrosion resistance tended to increase with increasing heat input. Heat input values between 95 and 110 J/mm are recommended for the optimization of corrosion resistance and strength.

Hardfacing coatings involve hard carbide/boride phases dispersed in a relatively soft steel matrix. For the hardness measurements of hardfacing coatings, depending on the micro structure, both the hardness test method and the applied load affect the hardness results; therefore, they affect the wear performance predictions of the coating. For this reason, the proper hardness test method should be determined according to the microstructure of the coating, and the reliability of the obtained hardness data should be established. This study aimed to determine the most suitable hardness test method for hypoeutectic and hypereutectic microstructures of hardfacing coatings by analyzing the reliability of Rockwell-C and Vickers hardness test results. Reliability analyses showed that Rockwell-C is not a suitable hardness test method for hypereutectic hardfacing coatings. Based on the relationship between wear resistance and hardness, Vickers hardness method was found more suitable for the considered materials. © 2019, University of Science and Technology Beijing and Springer-Verlag GmbH Germany, part of Springer Nature.

The effect of the parameters of welding conducted by the method of cold metal transfer on the geometry of the welding pool, the ultimate tensile strength, and the corrosion rate of welded joints of sheets from aluminum alloy AA6061 is studied. The influence of the current, voltage, and heat input rate during welding on the properties of the welded joints is analyzed. The welding parameters providing maximum ultimate strength and high corrosion resistance of welded joints of alloy AA6061 are determined. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

The trend of using lightweight materials in the automotive industry brings along the necessity of dissimilar welding of aluminum alloys such as AA5754 and AA6061. Hybrid structures in automobiles are subjected not only to mechanical forces but also corrosive effects of the environment. In this study, cold metal transfer welding, which is suitable for welding thin sheets and dissimilar materials, was applied to join AA5754 to AA6061. It was aimed to investigate the effect of weld heat input on mechanical properties and corrosion rate measured by the Tafel extrapolation method in 3.5 wt.% NaCl solution at room temperature. The tensile strength of AA5754-AA6061 joints tended to reduce with increasing heat input. Corrosion test results showed that the increased heat input decreased the corrosion resistance and caused intergranular corrosion besides pitting corrosion. © 2019, ASM International.

A Sheet Metal Forming (SMF) process, especially deep drawing, is one of the manufacturing processes that commonly used in the automotive industry. Compared with casting and forging, the SMF process has several advantages, including lesser weight materials and broader variations in shape that can be made. The most important of the problems in the SMF process is the wrinkling phenomenon and tearing of sheet products. The wrinkle and tear occurs because of the mechanical properties of the material, product geometry, and blank holder force. The finite element based Computer-Aided Engineering (CAE) program AutoForm Plus R7 used in this article was used for analysis. Solidworks software was used during mold design. AutoForm is a highly productive software that provides high accuracy and reliable results, specially developed for the sheet metal forming mold industry, especially for the automotive industry. With AutoForm, multiple analyses were made by computational calculations, even before the mold production started, and with the help of these analyses, the closest to perfect mold outputs were obtained. In addition, optimum drawbead geometry and springback effect were analysed. The most suitable material was selected for the deep drawing product. DX54D + Z and DX56D + Z from continuously hot-dip coated steel flat products selected as analysis materials. As a result, the simulation reports obtained from this study were compared with many results in the literature. It is concluded that DX56D + Z sheet material can be used in deep drawing products without negative consequences such as tearing, wrinkling and shrinkage marks., Bir Sac Metal Şekillendirme (SMF) süreci, özellikle derin çekme, otomotiv endüstrisinde yaygın olarak kullanılan üretim süreçlerinden biridir. Döküm ve dövme ile karşılaştırıldığında, SMF işleminin daha az ağırlıklı malzemeler ve yapılabilecek daha geniş şekil varyasyonları dahil olmak üzere çeşitli avantajları vardır. SMF sürecindeki sorunlardan en önemlisi, tabaka ürünlerde kırışma olgusu ve yırtılmadır. Kırışıklık ve yırtılma, malzemenin mekanik özellikleri, ürün geometrisi ve boşluk tutucu kuvveti nedeniyle oluşur. Analiz için bu makalede kullanılan sonlu eleman tabanlı Bilgisayar Destekli Mühendislik (CAE) programı AutoForm Plus R7 kullanılmıştır. Kalıp tasarımı sırasında Solidworks yazılımı kullanıldı. AutoForm, özellikle otomotiv endüstrisi için sac şekillendirme kalıp endüstrisi için özel olarak geliştirilmiş, yüksek doğruluk ve güvenilir sonuçlar sağlayan son derece verimli bir yazılımdır. AutoForm ile kalıp üretimi başlamadan önce bile hesaplamalı hesaplamalarla çoklu analizler yapılmış ve bu analizler sayesinde mükemmele en yakın kalıp çıktıları elde edilmiştir. Ek olarak, optimum çeki topuzu geometrisi ve geri esneme etkisi analiz edildi. Derin çekme ürünü için en uygun malzeme seçildi. Analiz malzemeleri olarak seçilen sürekli sıcak daldırma kaplamalı çelik yassı ürünlerden DX54D + Z ve DX56D + Z. Sonuç olarak, bu çalışmadan elde edilen simülasyon raporları, literatürdeki birçok sonuçla karşılaştırılmıştır. DX56D + Z sac malzemenin derin çekme ürünlerinde yırtılma, buruşma ve çekme izleri gibi olumsuz sonuçlar olmadan kullanılabileceği sonucuna varılmıştır.

Hardfacing coatings are one of the methods used in many engineering applications to increase the wear and corrosion resistance of workpieces. This study aims to examine the changes in microstructure and wear properties by adding carbide forming elements of molybdenum and vanadium together to Fe-Cr-C based hardfacing alloys. Each coating contains both vanadium and molybdenum. 3%, 4% ferromolybdenum, and 10%, 12% ferrovanadium were added to the Fe-Cr-C alloys. It was observed that the microstructure of coatings consists of primary M7C3 (M: Fe, Cr) and M2C (M: Mo, Fe, Cr) carbides and fine-grained secondary carbides dispersed in the matrix. It was observed that increasingferromolybdenum and ferrovanadium addition reduces the carbide grain size. However, the volumetric carbide ratio and hardness showed an increasing trend with increasing ferrovanadium and ferromolybdenum. The highest hardness and consequently the lowest volumetric wear loss was determined in the coating including 4% ferromolybdenum + 10% ferrovanadium., Sert dolgu kaplamalar, pek çok mühendislik uygulamasında iş parçalarının aşınma ve korozyon direncini artırmak amacıyla kullanılan yöntemlerden biridir. Bu çalışmanın amacı, karbür yapıcı elementlerden molibden ve vanadyumun Fe-Cr-C esaslı sert dolgu alaşımlarına ilave edilerek mikroyapı ve aşınma özelliklerinde meydana gelecek değişimleri incelemektir. Her kaplama hem vanadyum hem de molibden içermektedir. Fe-Cr-C alaşımlarına %3, %4 oranlarında ferromolibden, %10, %12 oranlarında ferrovanadyum ilave edilmiştir. Kaplama içeriğinin primer M7C3 (M: Fe, Cr) ve M2C (M: Mo, Fe, Cr) karbürlerinden ve matrise yayılmış ince taneli sekonder karbürlerden oluştuğu gözlenmiştir. Artan ferromolibden ve ferrovanadyum ilavesinin karbür tane boyutunu küçülttüğü tespit edilmiştir. Bununla birlikte hacimsel karbür oranı ve sertlik artış eğilimi sergilemiştir. En yüksek sertlik ve buna bağlı olarak en düşük hacimsel aşınma kaybı %4 ferromolibden +%10 ferrovanadyum ilave edilen kaplamada tespit edilmiştir.

Son yıllarda ülkemizde yaşanan maden kazaları sebebiyle birçok can kaybı yaşanmıştır. Bundan dolayı madencilik ve tünel inşa sektöründe yeni araştırmalar ortaya çıkmıştır. Yeni gelişmelerle tünel kısa zamanda, düşük maliyet ve yüksek kalitede tamamlayarak projelerinde beklenen hassasiyeti güvence altına almak mümkündür. Geçmişten günümüze kadar tahkimat malzemeleri maden ve tünelcilik sektörünü etkilemiştir. Son zamanlarda madencilik ve tünelcilik sektöründe farklı amaçlar için kullanım alanlarına sahip malzemelerden biri çeliktir. Çelik, ahşaba göre daha yüksek dayanıma sahiptir, çeşitli mekanizmalara göre şekillendirilebilir ve bu mekanizmaların yükü altında bozulmadan kullanılabilir.Çelik tahkimat sistemlerde son zamanlarda kullanılan profil ise Toussaint-Heitzmann (TH)’dır. TH profili tahkimatların servis ömrünü büyük oranda etkileyen soğuk deformasyon proseslerinin kontrollü ve en verimli süreç tasarımları ile elde edilebilirliğini ortaya çıkarmıştır. Bu çalışmada, sıcak haddeleme yöntemi ile elde edilen S480W malzemesinden TH34 profiller için, madencilik ve tünelcilik sektöründe kullanımı amacıyla galeri kesitlerine göre profilin bükme ile şekil verme süreçleri, sonlu elemanlar yöntemi ile tasarlanmıştır. Elde edilen çıktılar ile birlikte prototip üretim gerçekleştirilmiştir. Referans alınan galeri ark ölçüsüne göre prototip üretimi gerçekleştirilen profilin büküm yüzeyleri tahribatsız muayene yöntemleri kullanılarak incelenmiş ve plastik deformasyon kaynaklı çatlak oluşuma rastlanılmamıştır. Elde edilen sonuçlara göre çelik tahkimatların soğuk plastik deformasyonuna (bükme) ait en verimli proses tasarımının gerçekleştirildiği belirlenmiştir.

Bu çalışmanın amacı, X6Cr17 ferritik paslanmaz çeliklerin yüzey özelliklerini, termal sprey yöntemlerden biri olan plazma sprey yöntemini kullanarak 0-100 um, 100-200 um ve 200-300 um kalınlığında Al2O3-Ti02 tozları ile kaplayarak geliştirmektir. Kaplama işleminden sonra numunelerin aşınma direnci araştırılmıştır. Aşınma Testleri, ASTM G133 standardına göre disk üzerinde pim yöntemi ile gerçekleştirilmiştir. Sonuçların incelenmesinden sonra, A3 numunesinin en yüksek aşınma direncine sahip olduğu gözlenmiştir., The aim of this study was to improve the surface properties of the X6Cr17 ferritic stainless steels by coating with the Al2O3-TiO2 powders in the thickness of 0-100μm, 100-200μm and 200-300μm by using the plasma spray method, one of thermal spray methods. Wear resistance of the samples was investigated after the coating process. The tests were carried out by pin-on-disc method according to ASTM G133 standard. After examination of the results, it was observed highest abrasion resistance of A3 sample. It was concluded that the abrasion resistance in the high hardness sample does not mean that it will be good due to the high hardness.

Otomotiv ve makine endüstrilerinde, yorulma dayanımı yüksek olan birçok parçanın imalatında; yüksek mukavemetleri, yüksek darbe dayanımları ve mükemmel yorulma performansları nedeniyle 51CrV4 çelikleri tercih edilmektedir. İçerdikleri Si, Mn, Cr ve V alaşım elementleri nedeni ile mekanik dayanımları yüksektir. Isıl işlem uygulanabilir ve sertleştirilebilir çelik grubunda yer alırlar. Yapılan bu çalışmada tavlama ve yağda soğutma adımlarından sonra farklı iki sıcaklıkta menevişleme işlemi uygulanan 51CrV4 çeliğinin morfolojik ve mekanik özelliklerindeki değişim incelenmiş ve menevişleme işleminin aşınma dayanımı üzerine olan etkileri tartışılmıştır. Çalışmanın sonucunda ferritik matris içinde karbür çökeltilerinden oluşan ve beynitik yapı içeren iki farklı mikroyapıya ulaşılmıştır. Kesit ve yüzeyden alınan sertlik ölçümlerinde belirgin bir farklılık gözlemlenmemiştir. Buna rağmen, yapılan çekme, çentik darbe ve kuru kum kauçuk aşınma testleri sonucunda numune grupları arasında belirgin farklılıklar gözlemlenmiş ve en uygun menevişleme sıcaklığının 315 C olduğu sonucuna varılmıştır.

Titanyum ve alaşımları, mekanik dayanımları ve biyotolerant yapıda olmaları nedeni ile biyomalzeme uygulamalarında tercih edilirler. Fakat insan vücudu içinde korozyona uğraması durumunda zararlı iyonların salınımına neden olabilirler. Hidroksiapatit ise seramik ve biyoaktif yapıda bir malzeme olup biyomalzemelerin korozyon dayanımlarını arttırmaya yönelik kaplama tabakası olarak kullanımı da mevcuttur. Bu çalışmada Ti6Al4V alaşımının korozyon dayanımını geliştirmek amacı ile sol-jel yöntemi kullanılarak hidroksiapatit kaplamalar yapılmıştır. Hazırlanan hidroksiapatit solüsyonlarına farklı oranlarda dietanolamin (DEA, C4H11NO2) eklenerek sol-jel prosesinde oluşması muhtemel olan çatlaklı yapılar kontrol edilmiş ve azaltılmaya çalışılmış ve kaplamanın genel morfolojisinde ve korozyon dayanımında meydana gelen değişikliklerin gözlemlenmesi amaçlanmıştır. Numuneler taramalı elektron mikroskobu (SEM-EDS) ve X-Işını kırınımı (XRD) kullanılarak analiz edilmiştir. Hazırlanan yapay vücut sıvısı içinde elektrokimyasal-potansiyodinamik korozyon testleri gerçekleştirilmiştir. Çalışmanın sonucunda DEA katkı oranının artması ile morfolojide çatlaklı yapıların azaldığı ve kaplama kalınlığının arttığı gözlemlenmiştir. DEA eklenmesinin korozyon dayanımını arttırdığı fakat DEA miktarındaki artışın korozyon dayanımını negatif etkilediği görülmüştür., Titanium and its alloys are preferred in biomaterial applications due totheir mechanical strength and biotolerant structure. However, if they arecorroded in the human body, they can cause the release of harmful ions.Hydroxyapatite is a ceramic and bioactive material, and it is also used as acoating layer for increasing the corrosion resistance of biomaterials. In thisstudy, hydroxyapatite coatings were made using sol-gel method in order toimprove the corrosion resistance of Ti6Al4V alloy. By adding different ratiosof diethanolamine (DEA, C4H11NO2) to theprepared hydroxyapatite solutions, cracked structures that are likely to occurin the sol-gel process have been checked and tried to be reduced. It has beenaimed to observe the changes in the overall morphology and corrosion resistanceof the coatings. Samples were analyzed using scanning electron microscopy (SEM-EDS)and X-Ray diffraction (XRD). Electrochemical-potentiodynamic corrosion testswere carried out in the prepared simulated body fluid. As a result of thestudy, it was observed that the cracked structures and the coating thicknessincreased in morphology with the increase in the DEA contribution rate. It wasseen that the addition of DEA increases the corrosion resistance, but theincrease in the amount of DEA negatively affects the corrosion resistance.

Within this work, the effect of etching parameters on the surface morphology of Ti6Al4V alloy was investigated. For this purpose, different temperatures, different proportions of HCl-H2SO4 acid mixtures and different etching times were used for the etching process. After etching, XRD analyses, SEM images and surface roughness values of the samples were presented. It was observed that increasing etching temperature facilitated the formation of pore structure on the surface, but after a certain temperature, the increasing temperature started to show negative effects. When all the microstructure images are considered, it is understood that acid concentration and etching time are effective parameters besides temperature difference.

Cold metal transfer (CMT) welding provides many advantages for welding of dissimilar materials and thin sheets with its superior heat input control mechanism. In this study, AA6061 and AA7075 aluminum alloys were joined with CMT welding. The effect of welding parameters on hardness, tensile strength, and corrosion rate was investigated. The Tafel extrapolation method was carried out to determine the corrosion rates of AA6061 and AA7075 base metals and AA6061–AA7075 joints. Increasing heat input was found to be detrimental for both mechanical properties and corrosion resistance. The outcomes showed that CMT welding produces adequate joints of AA6061–AA7075 in terms of mechanical properties and corrosion resistance, favorably with welding parameters that provide low heat input.

Aluminum/SiC composites are widely employed in the automotive industry. Aluminum composites can be produced by hot pressing which forms a final product with a low porosity level and a denser structure. Homogeneous distribution of reinforcement particles, the level of porosity, and heat treatment not only affect the mechanical properties of the composites but also the reliability of their mechanical test results. In this study, Brinell hardness test reliability analyses of the hot-pressed Alumix321/SiC composites were carried out. The effects of increasing SiC amount and aging treatment on the reliability of hardness test results were discussed. Reliability analysis revealed that the aging treatment and increasing amount of SiC reinforcement decreased the reliability of the hardness test results. The reason for this was researched and resulting cases were discussed. © 2019, The Indian Institute of Metals - IIM.

msufbd Korozyon, metalin çevresi ile arasındakikimyasal reaksiyonların bir sonucu olarak bozulmasıdır. Fakat korozyon, öncedentahmin edilebilir, bazı durumlarda önemli ölçüde yavaşlatılabilir veyaönlenebilir. Bu çalışmada, pek çok konstrüksiyonun oluşturulmasında kullanılanimalat yöntemlerinden biri olan kaynak çeşitlerinden soğuk metal transferkaynağı ile üretilen AA7075-galvanizli çelik bağlantılarda galvanik korozyonoluşumunun ve farklı bağlantıların gerilme dayanımına etkisi incelenmiştir.Alüminyum ve çelik çifti diğer kaynak yöntemleriyle birleştirilmesinin zorolduğu bir çifttir. Bu yöntem ile birleştirilme sağlanmıştır. Bu çalışmada, bağlantıda oluşacak korozyon incelenmiştir. Sonuç olarak, kaynak sırasındaartan ısı girişi galvanik korozyonu olumsuz yönde etkiledi ve malzemeçözünmesini arttırdığı tespit edilmiştir. Corrosion is the degradation ofthe metal as a result of chemical reactions with its surroundings. However, corrosion can be predicted, in some cases significantly slowed down orprevented. In this study, the effect of galvanic corrosion formation on the tensilestrength of AA7075-galvanized steel joints produced by cold metal transferwelding, which is one of the manufacturing methods used in forming manyconstructions, was investigated. The aluminum and steel pair are difficult tocombine with other welding methods. Joining is provided by this method.Corrosion in this joining was investigated in this article. As a result, increased heat input during welding adversely affected galvanic corrosion andincreased material dissolution. 540645

Son yıllarda ülkemizde yaşanan maden kazaları sebebiyle birçok can kaybı yaşanmıştır. Bundan dolayı madencilik ve tünel inşa sektöründe yeni araştırmalar ortaya çıkmıştır. Yeni gelişmelerle tünel kısa zamanda, düşük maliyet ve yüksek kalitede tamamlayarak projelerinde beklenen hassasiyeti güvence altına almak mümkündür. Geçmişten günümüze kadar tahkimat malzemeleri maden ve tünelcilik sektörünü etkilemiştir. Son zamanlarda madencilik ve tünelcilik sektöründe farklı amaçlar için kullanım alanlarına sahip malzemelerden biri çeliktir. Çelik, ahşaba göre daha yüksek dayanıma sahiptir, çeşitli mekanizmalara göre şekillendirilebilir ve bu mekanizmaların yükü altında bozulmadan kullanılabilir. Çelik tahkimat sistemlerde son zamanlarda kullanılan profil ise Toussaint-Heitzmann (TH)’dır. TH profili tahkimatların servis ömrünü büyük oranda etkileyen soğuk deformasyon proseslerinin kontrollü ve en verimli süreç tasarımları ile elde edilebilirliğini ortaya çıkarmıştır. Bu çalışmada, sıcak haddeleme yöntemi ile elde edilen S480W malzemesinden TH34 profiller için, madencilik ve tünelcilik sektöründe kullanımı amacıyla galeri kesitlerine göre profilin bükme ile şekil verme süreçleri, sonlu elemanlar yöntemi ile tasarlanmıştır. Elde edilen çıktılar ile birlikte prototip üretim gerçekleştirilmiştir. Referans alınan galeri ark ölçüsüne göre prototip üretimi gerçekleştirilen profilin büküm yüzeyleri tahribatsız muayene yöntemleri kullanılarak incelenmiş ve plastik deformasyon kaynaklı çatlak oluşuma rastlanılmamıştır. Elde edilen sonuçlara göre çelik tahkimatların soğuk plastik deformasyonuna (bükme) ait en verimli proses tasarımının gerçekleştirildiği belirlenmiştir. In recent years there have been many casualties due to mining accidents in our country and there have been searches and anticipations for new developments in mining and tunnel construction sector. With the emergence of new developments, it is possible to secure the expected precision of tunnel projects in a short time, at low cost and high quality. From past to present day, ground support materials have affected the orientation of the mining and tunneling sector. One of the materials that have recently been used for various purposes in the mining and tunneling sector is steel. Steel is higher in strength than wood and can be shaped according to various mechanisms and can be used undisturbed under a load of these mechanisms. The profile recently used in steel support systems is Toussaint-Heitzmann (TH). The TH profile reveals that the cold deformation processes affecting the service life of the ground supports can be achieved with controlled and efficient process designs. In this study, S480W material TH34 profiles obtained by the hot rolling method are designed by using finite element method for bending and shaping processes according to gallery sections for use in mining and tunneling sector. Prototype production was carried out with the results obtained. According to the reference gallery arc gauge, the bending surfaces of the profile produced prototype were examined by using non-destructive inspection methods and crack formation due to plastic deformation was not found. According to the results obtained, it has been determined that the most efficient process design for cold plastic deformation (bending) of steel ground supports is carried

Minimizing wear would ensure reduced loss of material, labor and time for numerous branches of industry. Hardfacing coating method is a promising application to overcome this loss. The purpose of the the hardfacing application is to support, repair or improve the surface that is susceptible to abrasion by forming hard phases. The present study was aimed to investigate the wear resistance of iron-based hardfacing coatings which were produced with Fe-Cr-C-B and Fe-Cr-C based filler wires, according to ball-on-disc and dry sand rubber wheel wear tests. During the open arc welding process powder compositions of 100% FeB and 40% FeB + 60% FeCr were transferred to the weld pool, in order to enrich the coating with boron and chromium. Increased FeB content ensured the formation of boride phases such as Fe2B, CrB2, B6Fe23, Cr5B3. Minimum wear loss was obtained in a sample which was coated with Fe-Cr-C-B based filler wire reinforced with 40% FeB + 60% FeCr powder. Formation of massive carbide/boride phases and a tough matrix protected by the high amount of secondary carbides increased the wear resistance. The outcomes showed that the wear resistance is not only correlated with hardness but also affected by the morphology of microstructural constituents. © 2018 Elsevier Ltd

Bu çalışmada, soğuk dövme yöntemi kullanılarak üretilmiş bağlantı elemanına ait kılcal çatlakların Eddy Current sistemi ile analiz edilerek verilerin mikroyapı sonuçları ile karşılaştırılması gerçekleştirilmiştir. Soğuk Dövme yöntemi, malzemeyi plastik deforme ederek şekil verme işlemidir. Bu yöntem ile üretilen bağlantı elemanlarında seri üretim öncesi ön kontrol yapılmadığı takdirde hammadde kaynaklı, soğuk deformasyon kaynaklı, proses ve proses tasarımı kaynaklı iç - dış yüzeylerde çatlak oluşumu kaçınılmazdır. Mamul kafa ve vida dişlerinde olabilecek çatlakların varlığı, tahribatsız muayene yöntemlerinden biri olan Eddy Current yöntemi ile araştırılmıştır. Yapılan Eddy Current tahribatsız muayene deneylerinde mamül şekli ve diş şekline göre uygun olan özel proplar kullanılmış, bu proplardan gelen sinyaller değerlendirilmiştir. Çatlak sinyali veren parçaların mikroyapı ve göz ile incelemesi neticesinde; parçaların, gelen uyarı sinyallerine uygun olarak yapılarında çatlak olduğu tespit edilmiştir.

AA5754 alüminyum alaşımı,otomobillerin iç ve dış panellerinde yaygın olarak kullanılmaktadır. Buçalışmada, soğuk metal transferi (CMT) ile birleştirilen 2 mm kalınlığındakiAA5754 levhaların, kaynak işlemi sonrası korozyon hızının araştırılmasıamaçlanmıştır. Kaynak işlemi ER5356 dolgu teli kullanılarak 73.97, 86.18,108.99 J/mm ısı girdisi değerlerinde gerçekleştirilmiştir. Isı girdisininkorozyon hızına etkisi Tafel ekstrapolasyon yöntemi ile belirlenmiştir. Isıgirdisinin artmasıyla korozyon hızının arttığı tespit edilmiştir. Korozyonauğramış yüzeyler taramalı elektron mikroskobu (SEM) ile incelenmiştir.&nbsp, AA5754 aluminium alloy are widely used in outer andinner panels of automobiles. Present study aimed to investigate the corrosionrate of cold metal transfer (CMT) welded 2 mm thick AA5754 sheets. Weldedsheets were produced with 73.97, 86.18, 108.99 J/mm heat input values usingER5356 filler wire. Effect of heat input on corrosion rate was determined byTafel extrapolation method. It was determined that corrosion rate increasedwith increasing heat input. Corroded surfaces were viewed by SEM. Hardness testwas applied and maximum hardness values were observed in weld metal.

In this study, micro-nanoporous TiO2 films were prepared by electrochemical anodization of titanium (Gr-2) in an aqueous solution containing 0.5 wt. % HF solution at a constant potential of 30 V and then annealed in ambient air at 500, 600, 700 and 800 °C for 2 h to obtain crystalline structures. The crystalline phase and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic performances of the samples were evaluated by the photocatalytic degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods. XRD results indicated that at annealing temperatures higher than 600°C, anatase started to transform into rutile. Increasing annealing temperatures resulted in reduced micro-nanopores diameter and increased wall thickness. At 800°C, the structure completely disappeared. The results demonstrated that changes in both the crystalline structure and surface morphology have a strong influence on the photoactivity of the nanostructured TiO2 films. © 2018, Turkish Chemical Society. All rights reserved.

Cold Metal Transfer (CMT) is a modified gas metal arc welding method. This method is different from conventional gas metal arc welding methods. In this process the heat input and the formation of spatter are reduced with the control of the wire movement and arc. So, CMT welding became indispensable in the welding of thin sheets. The importance of lightweight structures in vehicles is increasing day by day, so the use of thin sheet aluminum alloys such as AA5754 is becoming increasingly widespread. In present study, 2mm thick AA5754 sheets were joined with cold metal transfer welding using ER5356 (AlMg5) filler wire. The effect of heat input on the weld quality was investigated. Microstructural examinations were executed by optical microscope and SEM. Mechanical properties of joints were determined by tensile and bending tests. It was found that increasing heat input did not have a significant effect on tensile strength of AA5754-AA5754 joints, while it corrupted the bending strength.

This study aims to investigate the weldability of 1050 aluminum alloy (AA1050) and galvanized 1314 steel by the cold metal transfer (CMT) procedur, comparing it with respective welding of similar aluminum sheets. Mechanical properties of welded specimens were determined by tensile testing and hardness measurements. The study was completed by microstructural analysis. The results showed that CMT welding can be applied successfully to join aluminum and steel.

This study was aimed to investigate the welding parameters on mechanical behavior of 2 mm thick AA1050 sheet materials joined by cold metal transfer (CMT) method. Macro structural examination showed that decreasing heat input decreased the pore size in the weld metal. Tensile test was applied and failure occurred in heat affected zone of aluminum sheet metal. Maximum tensile strength was found in the sample with minimum heat input. Heat affected zone was observed explicitly in the sample produced with the maximum heat input. Decreasing joint gap affected the bending strength positively. Bending strength was found superior with maximum bonding line length.

PurposeIt is important to know the friction coefficient and wear loss for determination of tribological conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. The purpose of this paper is to determine friction coefficient and wear loss at CuSn10 alloy radial bearings by a new approach. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities.Design/methodology/approachIn this study, friction coefficient and wear losses of journal and bearing have been determined by a new approach with a radial journal bearing test rig and artificial neural networks (ANNs) method. The ANN typifies a learning technique that enables the hidden input‐output relationship to be mapped accurately. Bronze‐based materials have been used as bearing material. Effects of friction coefficient and wear losses have been examined at same load and velocity and at dry and lubricated conditions.FindingsThe results obtained in ANN application are close to friction test results for dry and lubricated conditions. Therefore, by using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. Experimental studies will be increased and research with ANN will be continued.Originality/valueBy using trained ANN values, the intermediate results that were not obtained in the tests can be calculated. The training finished on 30 min whereas experimental study had continued day after day.

Retrogression and re-aging (RRA) process are applied in an attempt to enhance mechanical properties and corrosion resistance of 7075 aluminium alloys. In this study, retrogression and re-aging process have been applied to a 7075 aluminium alloy at 170°C for 5, 40, 80 min and wear resistance of RRA applied samples have been investigated by ball-on-disc wear test apparatus. Sliding distance has been chosen as 300 meters. Re-aging procedure has been carried out at 125°C for 10, 20 and 30 hours. Minimum wear loss has been obtained by retrogression for 40 min and aging for 30 hours.

In this study, the effect of pre-aging time and temperature on mecha­nical properties of aluminium alloys 6082 and 7075 has been investigated. Pre-aging has been applied at 50, 60, 70 and 80 °C for 24, 72, 144 hours after solution treatment process at 560 °C for 1 hour. Then these samples have been subjected to an aging process at 180 °C and 125 °C. The hardness of samples has been measured during aging process regularly. Eventually, it was determined that if pre-aging process is performed at low temperature, an increase of hardness occurs and hardness decreases with increasing temperature during aging.

For this study 5083 Aluminium alloy plates, as used in automobiles and watercraft, were experimentally MIG welded. The plates were joined with different wires and at various currents. The effects of welding with different parameters on the mechanical and corrosion properties were investigated. The corrosion behaviour of the MIG welded 5083 Aluminium base material was also investigated. The effects of the chemical composition of the filler material on the mechanical properties were examined by metallographic inspection and tensile testing. By EDS and XRD analyses of specimens it turned out that different structures in the weld metal (Cu3Si) affect its mechanical properties. The mechanical properties of the specimens welded with 5356 filler metal were found as quite well improved as compared to those specimens welded with 4043 and 5183 filler material. The results of the metallographic analysis, and mechanical and corrosion tests exhibited that the 5356 filler material was most suitable for the 5083 Al alloy base material.

In this study, wear behaviors of aged aluminium AA 2024 and AA 6063 alloys were investigated. AA 2024 and AA 6063 aluminium alloys were solution treated at two different temperatures of 490 and 520 °C. Then all samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140 °C, 180 °C and 220 °C) for five different periods of time (2, 4, 6, 8, 10). The microstructures of the aged samples were examined by optical microscope, SEM-EDS and X-ray analysis. The hardness values of the aged samples were measured by microhardness tests. Wear tests were carried out on the pin-on-disc model wear test apparatus under sliding velocity at 2 m s −1 speed, 400, 800, 1200 and 1600 m sliding distances for 10, 20 and 30 N variable loads. The mass-loss values of the aged samples were tested by wear tests. As a result of this study, the hardness of the second phase precipitated samples was found to be higher than that of the as-cast samples and it increased with increasing the solution temperature and aging periods. The study also revealed that the wear rate and friction coefficient can be decreased with increasing the solution temperatures and aging periods.

In this study, Al99—SiC composites were produced using PM method. In the composites produced, the reinforcement rates of SiC were 0, 5, 10, and 20 (%wt). The matrix Al 99 powders were mechanically mixed with SiC particulates. These powders were compacted at room temperature at 500 MPa for 5 × 10 × 60 mm specimens and followed by sintering at 600 and 620°C for 1 h. Composite specimens were joined by CO2 laser welding method. Rofin—Sinar SM2000 machine was used for the welding process. The microstructure of melted region was investigated by optical, scanning, and X-ray microchemical analysis techniques. The hardness test, tensile test, and three-point bend test results were presented. The effect to CO2 laser welding method at different reinforcement rates and different sintering temperatures in Al 99 powder was investigated. Because of the lower thermal conductivity of Al99—SiC composites, melting zone is wide. It was observed that 0.5 m/min laser welding velocity was suitable for composites with low SiC rate (0% and 5% SiC), and with increasing SiC (10 and 20%), laser welding velocity of 0.3 m/min was suitable.

The aim of this paper is to investigate age hardening behavior of PM AA2014 alloy. The specimens were made by powder metallurgy (PM) method. During the PM the product was made from powder basic materials by pressing (at 600 MPa) and sintering (600 ± 5 °C, 610 ± 5 °C, 620 ± 5 °C). There were three steps that occur in age-hardening; solution treatment (510 ± 5 °C), quenching (water) and aging (20 °C, 150 ± 5 °C, 200 ± 5 °C). Metal microscopy and micro Vickers hardness test were carried out to characterize the structure properties resulting from different aging temperature. The hardness test results showed that the sintering temperature, suitable solution treatment and aging operations has great influence on hardness characteristics of the PM alloys.

Artificial neural networks (ANNs) are a new type of information processing system based on modeling the neural system of human brain. Effects of ageing conditions at various temperatures, load, sliding speed, abrasive grit diameter in 6351 aluminum alloy have been investigated by using artificial neural networks. The experimental results were trained in an ANNs program and the results were compared with experimental values. It is observed that the experimental results coincided with ANNs results.

Knowing friction coefficient is important for determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. In this study, friction coefficient at CuSn10 Bronze radial bearings has been determined by a new approach as experimental and artificial neural networks method. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities.

Statistically processed data on the microstructure and wear of aged aluminum alloys AA2024 and AA6063 are presented. Results of wear tests are analyzed using multidimensional analysis of variance (MANOVA) with 95% confidence interval for statistically significant deviations. It is shown that the temperature and the duration of the aging are statistically significant factors affecting wear of aluminum alloys 2XXX and 6XXX.

WOS: 000299981200008, In this study, the effect of aging heat treatment on the hardness of AA 2024 and AA 6063 aluminum alloys was investigated by experimental and an Artificial Neural Network (ANN). AA 2024 and AA 6063 aluminum alloys were solution treated at two different temperatures of 490 degrees C and 520 degrees C. Then both samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140 degrees C, 180 degrees C, 220 degrees C) for ten different periods of time (2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 h.). The experimental results were trained in an ANNs program, and the results were compared with experimental values. It is observed that the experimental results coincided with the ANNs results., Zonguldak Karaelmas University Research committeeBulent Ecevit University [2006700101], The authors are grateful to Zonguldak Karaelmas University Research committee as this study ihas been suggested and supported through grant (2006700101).

Surface modification of a Ti6Al4V titanium alloy was made by the plasma nitriding process. Plasma nitriding was performed in a constant gas mixture of 20% H2–80% N2 at temperatures between 700 and 1000° C and process times between 2 and 15 h. Samples nitrided at different treatment times and temperatures were subjected to the dry sliding wear test using the pin-on-disc set up under 80N normal load with rotational speed of counter face disc of 0.8 m/s at room conditions. An artificial neural network (ANN) model of was developed for prediction of wear performance of the plasma nitrided Ti6Al4V alloy. The inputs of the ANN model were processing times and temperatures, diffusion layer thickness, Ti2N thickness, TiN thickness and hardness. The output of the ANN model was wear loss. The model is based on the multilayer backpropagation neural technique. The ANN was trained with a comprehensive dataset collected from experimental conditions and results of authors. The model can be used for the prediction of wear properties of Ti6Al4V alloys nitrided at different parameters. The ANN model demonstrated the best statistical performance with the experimental results.

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A lot of experiments must be conducted in order to find an appropriate technology for the calculation of strength of the materials, which wastes both man power and money. For this reason artificial neural networks (ANNs) have been used to search the optimum technology proper for pre-aged AA 6063 aluminum alloy. In this study, ANNs were used to compare experimental results and test data were used for teaching of the ANNs. This paper examines the changes in the hardness of AA 6063 alloys when heat treated at different pre-aging treatments. The alloy was solution treated for 1 hour at 525±3 °C and quenched in water. After quenching, samples were subjected to five different pre aging times, 2 hours, I day, 3 days, 7 days. On the other hand, some specimens were not pre-aged. Artificial age temperatures were selected as 160 °C and 180 °C. The hardness values of these under-aged alloys were measured. When the pre-aging time was 7 days, the hardness values of the specimens increased. An excellent correlation was found between experimental hardness results and ANNs hardness results.