On arc efficiency in gas tungsten arc welding

Stenbacka, Nils

doi:10.1590/s0104-92242013000400010

Cited by 62 publications

(52 citation statements)

References 15 publications

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“…Electron beam has a slightly higher energy efficiency (15% -20%), but it requires a high vacuum working environment [16]. Compared with the poor energy efficiency of laser and electron beam, the energy efficiency of arc welding processes such as the Gas Metal Arc Welding (GMAW) or Gas Tungsten Arc Welding (GTAW) processes can be as high as 90% in some circumstances [17,18]. As a result, WAAM using either the GMAW or the GTAW process is a promising technology for manufacturing aerospace components with median to large size in terms of productivity, costcompetitiveness and energy efficiency [5,6,19,20].…”

Section: Introductionmentioning

confidence: 99%

A multi-bead overlapping model for robotic wire and arc additive manufacturing (WAAM)

Ding

Pan

Cuiuri

et al. 2015

Robotics and Computer-Integrated Manufacturing

396

132

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Wire and arc additive manufacturing (WAAM) is a promising alternative to traditional subtractive manufacturing for fabricating large aerospace components that feature high buy-to-fly ratio. Since the WAAM process builds up a part with complex geometry through the deposition of weld beads on a layer-by-layer basis, it is important to model the geometry of a single weld bead as well as the multi-bead overlapping process in order to achieve high surface quality and dimensional accuracy of the fabricated parts. This study firstly builds models for a single weld bead through various curve fitting methods. The experimental results show that both parabola and cosine functions accurately represent the bead profile. The overlapping principle is then detailed to model the geometry of multiple beads overlapping together. The tangent overlapping model (TOM) is established and the concept of the critical centre distance for stable multi-bead overlapping processes is presented. The proposed TOM is shown to provide a much better approximation to the experimental measurements when compared with the traditional flat-top overlapping model (FOM). This is critical in process planning to achieve better geometry accuracy and material efficiency in additive manufacturing. Abstract: Wire and arc additive manufacturing (WAAM) is a promising alternative to traditional subtractive manufacturing for fabricating large aerospace components that feature high buy-to-fly ratio. Since the WAAM process builds up a part with complex geometry through the deposition of weld beads on a layer-by-layer basis, it is important to model the geometry of a single weld bead as well as the multi-bead overlapping process in order to achieve high surface quality and dimensional accuracy of the fabricated parts. This study firstly builds models for a single weld bead through various curve fitting methods. The experimental results show that both parabola and cosine functions accurately represent the bead profile. The overlapping principle is then detailed to model the geometry of multiple beads overlapping together. The Tangent Overlapping Model (TOM) is established and the concept of the critical centre distance for stable multi-bead overlapping processes is presented. The proposed TOM is shown to provide a much better approximation to the experimental measurements when compared with the traditional Flat-top Overlapping Model (FOM). This is critical in process planning to achieve better geometry accuracy and material efficiency in additive manufacturing.

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Section: Introductionmentioning

confidence: 99%

A multi-bead overlapping model for robotic wire and arc additive manufacturing (WAAM)

Ding

Pan

Cuiuri

et al. 2015

Robotics and Computer-Integrated Manufacturing

396

132

View full text Add to dashboard Cite

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“…This can assume a value in a wide range for a TIG process (0.36 to 0.90), as it depends on several factors, such as material, arc length, torch velocity and so on. A value of 0.75 was selected both for the initial and repair weld, based on the material analysed [22]. Secondary effects due to the clamping system were not modelled.…”

Section: Thermal and Mechanical Boundary Conditionsmentioning

confidence: 99%

Residual stress analysis and finite element modelling of repair-welded titanium sheets

et al. 2017

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An innovative finite element modelling approach has been tested to investigate the effects of weld repair of thin sheets of titanium alloy, taking into account a preexisting stress field in the components. In the case study analysed, the residual stress fields due to the original welds are introduced by means of a preliminary sequentiallycoupled thermo-mechanical analysis and considered as preexisting stress in the sheets for the subsequent repair weld simulation. Comparisons are presented between residual stress predictions and experimental measurements available from the literature, with the aim of validating the numerical procedure. As a destructive sectioning technique was used in the reference experimental measurements, an investigation is also presented on the use of the element deactivation strategy when adopted to simulate material removal. Although the numerical tool is an approximate approach to simulate the actual material removal, the strategy appears to predict a physical strain relaxation and stress redistribution in the remaining part of the component. The weld repair modelling strategy and the element deactivation tool adopted to simulate the residual stress measurement technique are shown to predict residual stress trends which are

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“…The welds were considered to be done in a horizontal position and the effects of gravity were disregarded. The values of the welding arc efficiency η were taken from [23] and the effect of the material insertion was disregarded.…”

Section: Materials and Computational Simulationmentioning

confidence: 99%

Numerical Evaluation of Temperature Field and Residual Stresses in an API 5L X80 Steel Welded Joint Using the Finite Element Method

Nóbrega

Diniz

Silva

et al. 2016

Metals

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Metallic materials undergo many metallurgical changes when subjected to welding thermal cycles, and these changes have a considerable influence on the thermo-mechanical properties of welded structures. One method for evaluating the welding thermal cycle variables, while still in the project phase, would be simulation using computational methods. This paper presents an evaluation of the temperature field and residual stresses in a multipass weld of API 5L X80 steel, which is extensively used in oil and gas industry, using the Finite Element Method (FEM). In the simulation, the following complex phenomena were considered: the variation in physical and mechanical properties of the material as a function of the temperature, welding speed and convection and radiation mechanisms. Additionally, in order to characterize a multipass weld using the Gas Tungsten Arc Welding process for the root pass and the Shielded Metal Arc Welding process for the filling passes, the analytical heat source proposed by Goldak and Chakravarti was used. In addition, we were able to analyze the influence of the mesh refinement in the simulation results. The findings indicated a significant variation of about 50% in the peak temperature values. Furthermore, changes were observed in terms of the level and profile of the welded joint residual stresses when more than one welding pass was considered.

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On arc efficiency in gas tungsten arc welding

Abstract: The aim of this study was to review the literature on published arc efficiency values for GTAW and, if

Cited by 62 publications

References 15 publications

A multi-bead overlapping model for robotic wire and arc additive manufacturing (WAAM)

A multi-bead overlapping model for robotic wire and arc additive manufacturing (WAAM)

Residual stress analysis and finite element modelling of repair-welded titanium sheets

Numerical Evaluation of Temperature Field and Residual Stresses in an API 5L X80 Steel Welded Joint Using the Finite Element Method

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