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    Analysis of mechanical and microstructural properties of gas metal arc welded dissimilar aluminum alloys (AA5754/AA6013)
    (Elsevier Science Sa, 2021) Yuruk, Ali; Cevik, Bekir; Kahraman, Nizamettin
    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.
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    Effect of Continuous and Pulsed Currents on Microstructural Evolution of Stainless Steel Joined by TIG Welding
    (Carl Hanser Verlag, 2015) Durgutlu, Ahmet; Fındık, Tayfun; Gülenç Behçet; Çevik, Bekir; Kaya, Yakup; Kahraman, Nizamettin
    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.
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    Microstructure and mechanical properties of friction stir welded dissimilar 5754-H111-6013-T6 aluminum alloy joints
    (Carl Hanser Verlag, 2019) Yürük, Ali; Çevik, Bekir; Kahraman, Nizamettin
    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.