Papers by Keyword: Friction Stir Welding

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Authors: Ho Sung Lee, Koo Kil No, Joon Tae Yoo, Jong Hoon Yoon
Abstract: The object of this study was to study mechanical properties of friction stir welded joints of AA2219 and AA2195. AA2219 has been used as an aerospace materials for many years primarily due to its high weldability and high specific strength in addition to the excellent cryogenic property so to be successfully used for manufacturing of cryogenic fuel tank for space launcher. Relatively new Aluminum-Lithium alloy, AA2195 provides significant saving on weight and manufacturing cost with application of friction stir welding. Friction stir welding is a solid-state joining process, which use a spinning tool to produce frictional heat in the work piece. To investigate the effect of the rotation direction of the tool, the joining was performed by switching the positions of the two dissimilar alloys. The welding parameters include the travelling speed, rotation speed and rotation direction of the tool, and the experiment was conducted under the condition that the travelling speed of the tool was 120-300 mm/min and the rotation speed of the tool was 400-800 rpm. Tensile tests were conducted to study the strength of friction stir welded joints and microhardness were measured with microstructural analysis. The results indicate the failure occurred in the relatively weaker TMAZ/HAZ interface of AA2219. The optimum process condition was obtained at the rotation speed of 600-800 rpm and the travelling speed of 180-240 mm/min.
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Authors: Jong Hoon Yoon, Joon Tae Yoo, Kyung Ju Min, Ho Sung Lee
Abstract: It is well known that the significant weight reduction and increased strength have placed advanced aluminum-lithium alloys at the forefront of aerospace materials research. For example the use of aluminum-lithium based alloys for rocket fuel tank domes can reduce weight because aluminum-lithium alloys have lower density and higher strength than Al-Cu alloy 2219. However, Al-Li alloys have been shown the inherent low formability characteristic that make them susceptible to cracking during the spinning operations. In this study a novel heat treatment process on the formability of friction stir welded Al-Li alloy blanks are presented. It is shown that the successful heat treatment process has been developed with superior mechanical properties and currently the patent is applied.
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Authors: Ho Sung Lee, Jong Hoon Yoon, Joon Tae Yoo
Abstract: Since solid state welding is formed from an intimate contact between two metals at temperatures below the melting point of the base materials, the structural integrity of welded zone is maintained without presence of foreign materials or temporary liquid phase. This paper provides some of examples for solid state joining of aerospace materials. Diffusion bonding process was developed for a titanium alloy for lightweight sandwich panels. Diffusion bonding of copper and stainless steel was also demonstrated to manufacture a combustion chamber. HIP (Hot Isostatic Press) bonding and friction stir welding process of aluminum alloy was developed in order to study possible application for a large launcher fuel tank. It is shown that solid state joining processes can be successfully applied to various aerospace materials and provide innovative solution for lightweight structures.
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Authors: Jean Pierre Bergmann, Michael Grätzel, René Schürer, Anna Regensburg, Markus Weigl
Abstract: Within the last decade, Friction Stir Welding (FSW) has increasingly been gaining relevance for joining nonferrous metals, especially aluminum alloys. Possible applications range from the aerospace and automotive sector up to manufacturing electrical components. Compared to conventional fusion welding processes, FSW offers numerous advantages, as it for example does not require shielding gas or filler material. However, FSW is still not applied or taken into account during the product development process in proportion to its potential. This is mainly caused by the lack of data in order to evaluate the process economically and differentiate it to other processes like arc and laser welding, also regarding technological factors. Therefore, this investigation focusses on the possibilities and limits when joining wrought and cast aluminum alloys, like EN AW-6082 T6, EN AW-7075 T651 and AlSi11Mg0,3, respectively, by FSW compared to MIG. The weld quality of the samples is characterized by tensile testing, hardness measurements and microstructure analysis. Furthermore, an approach to reduce the process forces by using FSW tools with reduced diameters and respectively adjusted process parameters is presented.
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Authors: K.K. Ramachandran, N. Murugan, S. Shashi Kumar
Abstract: Friction Stir Welding (FSW) as a joining technique with regard to low melting temperature materials such as aluminum alloys has already been established and implemented in the industry. But, with regard to high melting temperature metals and alloys the major issue still to get successfully addressed is a pertinent tool material for a class of work materials and to get their operating parameters optimized. This paper presents a detailed assessment on the FSW of high melting temperature (HMT) materials, giving emphasis on the tool materials, tool geometry and FSW equipment aspects based on the information gathered from experimental studies and research publications.
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Authors: S. Shashi Kumar, N. Murugan, K.K. Ramachandran
Abstract: The aim of the present study is to investigate on mechanical and microstructural properties of Friction Stir Welded 316 L austenitic stainless steel. Defect free weld were produced at a tool rotational speed (N) of 600 rpm, transverse speed (V) of 45 mm/min, axial force (F) of 11 kN and tool tilt angle (T) of 1.50.Mechanical properties such as Ultimate Tensile strength (UTS), Percentage Elongation (PE), Impact Strength (IS) were evaluated on the welded specimen. Further,micro hardness and microstructural analysis were carried out the transverse direction to the welded specimen. No significance of HAZ in the welded joint with observation of sigma phase precipitation revealed by Groesbeck and Modified Mukrami reagent. Further,FESEM with Electron Dispersive Spectroscopy (EDS) were obtained at the stir zone to ensure constituent of alloying elements present and ensuring no secondary phases found in the stir zone.
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Authors: Azman Ismail, Mokhtar Awang, Mohd Afendi Rojan
Abstract: A dedicated or specialized friction stir welding (FSW) machine is quite costly especially for pipe joining. Therefore, not many institutions manage to conduct their research on FSW at their facilities. Besides that, the difficulty to design a jig that can hold the complex shape such as pipe section tightly and easily to be removed during and after the FSW process respectively will nullify the intentions. In many institutions, there was either conventional or CNC milling machine available in their workshops. Thus, a jig called orbital clamping unit (OCU) was designed to suit this milling machine. It acts as an additional device to enable this milling machine to run as FSW machine at a lower cost, hence fully utilized the available facility in the workshop. Several good samples were successfully produced by using this jig and milling machine
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Authors: C. Chanakyan, P. Dinesh Babu, M.P. Jenarthanan, K. Jagathesh
Abstract: The aim of this project is to study the micro-structural and mechanical property changes during friction stir welding [FSW] with a special focus on AA5052. The objective of this project is to experimentally investigate the influence of tool pin profiles (straight cylinder, fluted cylinder and pentagonal cylinders) and welding input parameters (rotational speed and traverse speed) on microstructure and mechanical properties (tensile strength, hardness) of AA5052 Al in FSW process. The detailed micro-structural analyses are carried out on the base metal and welded zone (nugget zone), Thermo mechanically affected zone and heat affected zone. The mechanical properties such as, tensile and hardness are studied before and after FSW process.
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Authors: Koo Kil No, Joon Tae Yoo, Jong Hoon Yoon, Ho Sung Lee
Abstract: Aluminum alloy 2219 is widely used in aerospace applications since it has a unique combination of good weldability and high specific strength. Furthermore, it can provide a high strength after heat treatment with superior properties in cryogenic environment so they have been widely used for cryogenic fuel tank of space launch vehicles. It is known that solid state welding like friction stir welding can improve the joint properties of this alloy. Friction stir welding is a solid state welding technology which two materials are welded together by the frictional heat due to the rotation of the tool. In this study, friction stir welding was performed on aluminum alloy 2219 sheets. The range of welding parameter is four rotation speeds from 350 to 800 rpm and six travel speeds from 120 to 420 mm/min. The results include the microstructural change after friction stir welding. The microstructure was characterized and material in the stirred zone experience sufficient deformation and heat input which cause the complete dynamic recrystallization. The present work represents the strength at each process condition and the optimum friction stir welding process parameters. The optimum weld efficiency obtained in this study was 76.5 %.
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Authors: Mohamed Ackiel Mohamed, Yupiter H.P. Manurung, Markus Laakkonen
Abstract: Tensile residual stress in friction stir welded (FSW) Aluminum alloy joints is well known to be detrimental to fatigue resistance properties of joints imperiled to dynamic loading. Hence, it is important to translate the prevailing tensile residual stress to a more favorable compressive residual stress to enhance the fatigue life cycle of the welded joints. In this study, the longitudinal and transverse residual stress for FSW AA 6061 joints is measured using the hole-drilling method with electronic speckle pattern interferometry (ESPI) for various conditions. This method combines the tried-and-true hole-drilling method with digital imaging and ESPI, eliminating the application of a strain gage through stress depth profile measurements by incremental drilling. The residual stress is measured for the FSW as-welded and high frequency mechanical impact/pneumatic impact treatment (HFMI/PIT)-treated conditions.
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