Yazar "Caligulu, Ugur" seçeneğine göre listele

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    The Effect of Welding Speed on the Laser Welding of AISI 430 Ferritic Stainless-AISI 1010 Low-Carbon Steel
    (Carl Hanser Verlag, 2009) Taskin, Mustafa; Caligulu, Ugur; Kolukisa, Sedat
    In this study, the effect of welding speed on the laser welding of AISI 430 ferritic stainless steel with AISI 1010 low-carbon steels was investigated. Laser welding experiments, were carried out under argon atmosphere, 2000 W constant welding power and 100, 200,300 cm/min welding speeds. The microstructures of the welded joints were examined by optical microscopy and SEM analysis. The tensile strength of the welded joints was measured. The result of all observations, tests and measurements indicated that the best properties were observed at the specimens welded at 100 cm/min welding speed.
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    Effects on Mechanical and Physical Properties of Ta Element Addition to Ti-6Al-7Nb Alloy
    (Springer, 2024) Caligulu, Ugur; Durmus, Hulya; Kejanli, Haluk; Keskinkilic, Ali Riza; Balci, Esra
    Ti and its alloys play a leading role in biomedical applications within the field of materials science. In this study, different amounts of Ta were added to the TiAlNb alloy. Various analyses were carried out to determine the physical and chemical properties of the produced samples. DSC (differential scanning calorimetry), and XRD (X-ray diffraction) analyses were conducted to determine the phase transformations and crystal structure of the alloys, respectively. SEM-EDX (scanning electron microscopy) and OM (optical microscopy) images were taken to analyze the chemical structure of the samples and to examine their microstructures in more detail. Microhardness and wear resistance tests were performed to determine some mechanical properties of the produced samples. It was observed that increasing the tantalum content increased both hardness and wear resistance. These findings suggest that the addition of tantalum to the Ti-6Al-7Nb alloy could be an effective strategy to improve biomaterial performance.
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    Interface characterization of CO2 laser welded austenitic stainless steel and low carbon steel couple
    (Emerald Group Publishing Ltd, 2012) Caligulu, Ugur; Taskin, Mustafa; Kejanli, Haluk; Orhan, Ayhan
    Purpose - The purpose of this paper is to investigate interface characterization of CO2 laser welded AISI 304 austenitic stainless steel and AISI 1010 low carbon steel couple. Laser welding experiments were carried under argon and helium atmospheres at 2000, 2250 and 2500 W heat inputs and 200-300 cm/min welding speeds. Design/methodology/approach - The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and X-Ray analysis. The tensile strength of the welded joints was measured. Findings - The result of this study indicated that the width of welding zone and HAZ became much thinner depending on the increased welding speed. On the other hand, this width widened depending on the increased heat input. Tensile strength values also confirmed this result. The best properties were observed at the specimens welded under helium atmosphere, at 2500 W heat input and at 200 cm/min welding speed. Originality/value - There are many reports which deal with the shape and solidification structure of the fusion zone of laser beam welds in relation to different laser parameters. However, the effect of all influencing factors of laser welding has up to now not been extensively researched. Much work is required for understanding the combined effect of laser parameters on the shape and microstructure of the fusion zone. This paper, therefore, is concerned with laser power, welding speed, defocusing distance and type of shielding gas and their effects on the fusion zone shape and final solidification structure of some stainless steels.
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    AN INTRODUCTION TO RADIOGRAPHY EXAMINATION METHOD IN THE INSTRUCTION ON WELDING
    (Int Council Materials Education, 2020) Kejanli, Haluk; Gur, Ali Kaya; Turkmen, Mustafa; Caligulu, Ugur
    The radiography examination method is used to detect defects both inside and on the surface in the weld seams in metals and alloys. We describe the radiography examination method for instructional purposes. We provide an example of radiographic testing of AISI 1010 steel + copper materials welded by friction welding in a direct-drive type friction-welding machine. The subsequent radiographic testing shows that such a pair can be welded with adequate strength via the friction welding technique. The amount of flash increases in all specimens with increasing rotational speed, friction pressure, and forging pressure. On the other hand, as friction time increased, the amount of flash decreases.
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    Radiographic inspection of AISI 420 steel friction welds
    (Carl Hanser Verlag, 2018) Kati, Nida; Cay, Vedat Veli; Ozan, Sermin; Caligulu, Ugur; Turkmen, Mustafa
    In this study, X-ray radiographic tests of AISI 420 steel welded by friction welding were studied. During the welding process, three different rotations, 700, 1000 and 1300, were employed while the other parameters such as friction pressure, friction time, upsetting-pressure and upsetting-duration were unchanged. After the completion of welding process, the welded joints were subjected to radiographic tests by X-raydiffraction. The result of the radiographic tests indicates that by increasing rotation speed the amount of flash and joining properties/performance increases in all samples. The best properties of the AISI 420 martensitic stainless steel joints were observed in samples welded at a rotation speed of 1300 (rpm). It has been determined that in harmony with the definition of welding defects and respective radiographic images, lack of fusion is the most common welding defect.