1,721,106 research outputs found
On The Friction Stir Welding of Titanium Alloys: Experimental Measurements and FEM Model Fine Tuning
No full textFriction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, is now being successfully used also for magnesium alloys, copper and steels. Recently, research is focusing on titanium alloys thanks to the high interest that such materials are getting from the industry as welding of titanium alloys by traditional fusion welding techniques presents several difficulties due to high material reactivity resulting in bonding with oxygen, hydrogen, and nitrogen with consequent embrittlement of the joint. In this way FSW represents a cost effective and high quality solution. The study of the temperatures reached at the varying of the main process parameters allows a deeper knowledge of the process enabling the prediction of the microstructural evolutions occurring during the process and dramatically influencing the mechanical properties of the obtained joints. In the paper a 3D FEM model of the FSW welding process, based on a thermo-mechanical fully coupled analysis, is presented. In particular the model is tuned following an inverse identification approach starting from welding temperatures on the tool acquired during FSW experiments on the widely commercially diffused Ti-6Al-4V alloy. The inverse approach led to the identification of the most correct friction factor to be introduced in the numerical model. The obtained results permit to asses that the tuned FEM model of the FSW process can be utilized as an effective design tool
On the Solid Bonding Phenomena in Linear Friction Welding and Accumulative Roll Bonding Processes: Numerical Simulation Insights
No full textSolid Bonding based welding processes allow to obtain defect free joints with low
residual stress and low distortion. However, the engineering and optimization of solid bonding
processes is difficult and requires a large number of time and cost consuming test trials. In this way,
proper numerical models are essential tools permitting effective process design.
The aim of this research was the comparison of the material process conditions during two
different manufacturing processes taking advantage of the same metallurgical phenomenon, namely
solid bonding. Linear Friction Welding, used to weld non-axisymmetric components and
Accumulative Roll Bonding, used to increase the mechanical properties of sheet metals, were
considered. Numerical models were set up, validated and used to design the process by studying the
complex material behavior during the solid bonding of different aluminum alloys.
An implicit approach was used for the Linear Friction Welding and Accumulative Roll Bonding
processes, leading to the understanding of the main process variables influence on the field
variables distribution and the occurrence of actual bondin
Micro and macro mechanical characterization of friction stir welded Ti–6Al–4V lap joints through experiments and numerical simulation
No full textProcess Mechanics in Friction Stir Welding of Magnesium Alloys: Experimental and Numerical Analysis
No full textAssessing single and multi-step friction stir consolidated recycled billets through uniaxial upsetting test
Full text linkFriction stir consolidation (FSC) represents a solid-state recycling technique that directly transforms machining waste into billets by the stirring action and friction heat of the rotating tool. This technology has demonstrated superior energy efficiency compared to remelting based traditional recycling methods. Concerning the FSC process mechanics, they impart temperature, strain and strain rate gradients across the billet sections leading to variations in mechanical properties such as hardness values and grain size distribution. Therefore, multi-step FSC variants were introduced to eliminate this inherent inhomogeneity inside the billets of the single-step FSC approach. However, the billets manufactured by multi-step methods showed better mechanical properties, and gradation across the billet section still persisted. This property led to the evolution of friction stir consolidation as a new manufacturing method for developing functionally graded materials. Previously, the gradation was highlighted by the Vickers hardness test and grain size distribution. Therefore, in the ongoing study, an advanced characterization technique was adopted by extracting miniaturized samples from the section of FSC billets and subjected them to the upsetting test. Employing advanced characterization techniques to get insights into the gradation and quality of billets manufactured through various process variants and will allow to draw a better conclusion regarding adoption of a more suitable FSC process varian
Modeling of the plastic characteristics of AA6082 for the friction stir welding process
No full textFocus of this paper is to model the plastic forming behavior of AA6082, in order to
develop the numerical FE analysis of the friction stir welding processes and the simulation of
subsequent forming processes. During the friction stir welding process, the temperatures reached
can range up to 500 °C and have a fundamental role for the correct performance of the process, so
the material data has to show a temperature dependency. Because of the tool rotation a strain rate
sensitivity of the material has to be respected as well. In this context, the general material
characteristics of AA6082 were first identified for different stress states. For the uniaxial state the
standard PuD-Al used in the automotive industry was applied, for the shear state the ASTM B831-
05 was used and for biaxial states the ISO 16842 was exploited. To characterize the plastic flow
behavior of the AA6082 at elevated temperatures, tensile tests were performed according to DIN
EN ISO 6892-2 from 25 °C to 500 °C with a strain rate from 0.1 s-1 up to 6.5 s-1
Effect of process parameters on the joint integrity in Friction Stir Welding of Ti-6Al-4V lap joints
No full textForming of metal-based composite parts
No full textIn the last few decades, metal-based composites and related manufacturing methods have attained a significant research attention thanks to the possibilities they offer to tailor both the material properties and the part in-service performances. A variety of metal-based composite parts is available for commercial applications since more affordable and robust manufacturing processes and quality control techniques have recently overcome many challenging technological issues. The paper aims at describing the forming processes applied to metal-based composites, with particular emphasis on the process features, part obtainable characteristics, and modelling issues for a convincing design and optimization of the process itself. The most recent progresses and challenges are illustrated in detail, including innovative materials and processes that are emerging to answer the requirements of advanced engineering applications as well as new modelling techniques and current approaches to face economic and environmental issues
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