Yazar "Durgutlu, Ahmet" seçeneğine göre listele
Listeleniyor 1 - 9 / 9
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Al - si alaşımının tig kaynağında darbeli akımın mikroyapı, sertlik, eğme ve çekme dayanımına etkisi(2008) Durgutlu, Ahmet; Kahraman, Nizamettin; Gülenç, BehçetBu çalışmada, AA 4000 serisi Al-Si alaşımı levhalar TIG kaynak yöntemi ile alternatif ve darbeli akım kullanılarak birleştirilmişlerdir. Kullanılan akım türünün kaynaklı birleştirmenin özelliklerine olan etkilerini görmek amacı ile birleştirilen numunelere mikroyapı, çekme, sertlik ve eğme testleri uygulanmıştır. Deneyler sonucunda, darbeli akımın düşük ısı girdisine, kaynak metalinde tane incelmesine ve alternatif akıma göre kaynak metali sertliğinde artışa neden olduğu belirlenmiştir. Birleştirmelere uygulanan çekme testlerinde, darbeli akım ile birleştirilen numunelerin alternatif akıma nazaran daha yüksek çekme dayanımı gösterdikleri tespit edilmiştir. Yapılan eğme testi sonucunda numunelerde yırtılma ve çatlak oluşumu gibi bir yüzey hatasına rastlanılmamıştır.Öğe The Effect of Pulsed Current on Microstructure, Hardness, Bending and Tensile Strength in TIG Welding of Al - Si Alloys(Gazi Univ, 2008) Durgutlu, Ahmet; Kahraman, Nizamettin; Gulenc, BehcetIn this study, AA 4000 series Al-Si alloys sheets were joined by TIG welding method using alternative and pulsed current. Tensile test, bending test, hardness test and microstructure examination of joined test specimens were carried out in order to see the effect of current type on mechanical properties of welded samples. Experimental results showed that, pulsed current leads to low heat input, grain refinement and hardness increase in weld metal compared to alternative current were used. Specimens joined by the pulsed current showed higher tensile strength than the specimens welded by the alternative current. After bending test, cracks, tearing and surface defection were not observed on the samples.Öğe INVESTIGATION OF THE EFFECT OF ELECTRODE EXTENSION DISTANCE ON MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF LOW CARBON STEEL WELDED WITH SUBMERGED ARC WELDING(Gazi Univ, 2005) Kahraman, Nizamettin; Gulenc, Behcet; Durgutlu, AhmetIn this study, the effect of electrode extension distance on metallurgical and mechanical properties of low carbon steel joints welded with submerged arc welding was investigated. OP 139 flux and OE S1 welding wire were used to weld steel parts using three different electrode extension distances. It is found that electrode extension distance effected the hardness and changed the microstructure of weld metal. It was seen that increasing electrode extension distance reduced the hardness of weld metal and HAZ. Tensile tests showed that rupture occurred in the base metal of all samples. Impact tests revealed that the best toughness value was obtained from the sample welded using 24 mm electrode extension distance.Öğe Investigation of the Microstructural, Mechanical and Corrosion Properties of Grade A Ship Steel-Duplex Stainless Steel Composites Produced via Explosive Welding(Springer, 2017) Kaya, Yakup; Kahraman, Nizamettin; Durgutlu, Ahmet; Gulenc, BehcetGrade 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.Öğe An Investigation of TIG Welding of AZ31 Magnesium Alloy Sheets(Carl Hanser Verlag, 2014) Demir, Bilge; Durgutlu, AhmetIn this study, butt welding of commercial AZ31 magnesium alloy sheets has been investigated by using the tungsten inert gas welding process with alternating and pulsed current. Magnesium alloy welding, although well developed and understood, can present some problems, such as porosity, hot cracking, oxide formation, etc.. Samples of the welded parts have been examined by optic microscopy and mechanic tests. Results showed that porosities and homogeneous micro size oxides were rarely found. Orientation of the weld microstructure in direction of the heat transfer were also rarely observed and equiaxed grain morphology was the dominant grain structure as in the base metals. In addition, fusion zone and HAZ of the welded samples have generally shown twins. This seems to be a very dominant grain type particularly in pulsed samples. Hot cracking was not observed in any samples. Results of mechanical tests showed that pulsed current seems to generate more favorable higher mechanical properties of weld joints than alternating current for magnesium alloys.Öğe Joining of Titanium Pipes with Laser Welding Method and Characterization of the Welding Zone(Gazi Univ, 2021) Uygunturk, Erkan; Kahraman, Nizamettin; Durgutlu, Ahmet; Gulenc, BehcetThe 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.Öğe Nokta direnç kaynağı ile birleştirilen titanyum levhaların çekme-makaslama dayanımlarının taguchi metoduyla optimizasyonu(2019) Yıldırım, Mehmet Serkan; Kaya, Yakup; Çakıroğlu, Ramazan; Gülenç, Behçet; Kahraman, Nizamettin; Durgutlu, AhmetBu çalışmada; düşük yoğunluk, yüksek dayanım ve mükemmel korozyon direncinden dolayı havacılık, uzay ve kimya endüstrilerinde oldukça yaygın olarak kullanılan ticari saf titanyum(Grade 2) levhalar, nokta direnç kaynak yöntemi ile birleştirilmiştir. Birleştirme işlemlerinde; farklı elektrod kuvveti (3 ve 6 kN), kaynak akımı(3,5 ve 7 kA) ve kaynak süresi (10,20 ve 30 çevrim) kullanılarak, kaynak parametrelerinin çekme-makaslama dayanımında etkisi incelenmiştir. Çekme-makaslama testi sonuçları 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 dayanımı sonuçlarına, kaynak parametrelerinin etkisi varyans analizi (ANOVA) metodu kullanılarak incelenmiş ve en etkin parametrenin %45.82 ile kaynak akımı olduğu tespit edilmiştir.Öğe Optimization of Tensile Strength of Titanium Plates Jointed Resistance Spot Welding with Taguchi Method(Gazi Univ, 2019) Yidirim, Mehmet Serkan; Kaya, Yakup; Cakiroglu, Ramazan; Gulenc, Behcet; Kahraman, Nizamettin; Durgutlu, AhmetIn this study, commercial titanium (Grade 2) plates, which are commonly used in aviation, space and chemistry industries because of its low density, high resistance and perfect corrosion resistance, are jointed by using spot resistance welding. In the process, the effect of welding parameters on tensile strength 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 tensile strength test were optimized with the characteristic of maximum-best control of Taguchi method. Optimum test combination for maximum tensile strength was designated as A2B3C3 (6 kN-7 kA-30 cycles). Effects of welding parameters on tensile strength results were analyzed with analysis of variant (ANOVA) method and the most effective parameter was determined as welding current with %45.82.Öğe Titanyum boruların lazer kaynak yöntemi ile birleştirilmesi ve kaynak bölgesinin karakterizasyonu(2021) Uyguntürk, Erkan; Kahraman, Nizamettin; Durgutlu, Ahmet; Gülenç, BehçetBu çalışmanın amacı, titanyum boruların lazer kaynak yöntemi ile birleştirilebilirliğinin araştırılmasıdır. Kaynak işlemleri üç farklılazer ışın gücünde (130, 140 ve 160 W) gerçekleştirilmiştir. Kaynak işlemleri esnasında ilave metal kullanılmış ve boru sabit hızdadöndürülerek, torç yatay pozisyonda konumlandırılmıştır. Birleştirme işlemi yapılan titanyum borulara kaynak işlemi sonundakaynak kalitesini ve mekanik özelliklerini belirlemek amacıyla, gözle muayene, çekme testi ve sertlik testi yapılmıştır. Ayrıcaiçyapıdaki 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 lazergücünde birleştirilen kaynaklı numunede kopma kaynak bölgesi dışından gerçekleşmiştir. Kaynaklı numunelere yapılan sertliktestleri sonucunda en yüksek sertlik değerlerinin kaynak metalinde, en düşük sertlik değerlerinin ise ana malzemede olduğu tespitedilmiştir.
