The effect of the cathode tip angle on the gas tungsten arc welding arc and weld pool: II. The mathematical model for the weld pool

Goodarzi, M.; Choo, R. T. C.; Takasu, Tomio; Toguri, J. M.

doi:10.1088/0022-3727/31/5/014

Cited by 45 publications

(36 citation statements)

References 9 publications

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“…The mathematical models [17,22] proposed by Goodarzi et al deal with this point. The authors indicate [17,22] that by decreasing the electrode tip angle the anode spot at the weld pool surface tended to be flatter, leading to a smaller heat flux and anode current density, that the gas shear stress increased due to gas flow, and that the two effects led to a wider weld pool.…”

Section: Effect Of the Cathode Tip Anglementioning

confidence: 99%

“…For a given arc length, increasing the tip angle leads to a weaker maximum of the heat flux density and to a wider radial spread. Otherwise, the heat flux density is maximal for a 60° tip angle and is more significant for a short arc length (roughly two millimeters) [17]. Regarding its influence on the weld pool shape, some authors point out a loss of penetration when the tip angle increases, whereas others see no effect [18].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration

2017

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Abstract:The weld pool shape created by the plasma arc interaction on a workpiece depends on many geometrical and physical parameters and on the operating conditions. Theoretical models are developed in such a way as to predict and to characterize the material. However, these models first need to be validated. Experimental results are hence proposed with parametric studies. Nevertheless, the interaction time is often short and the weld pool shape evolution not presented. In this work, the experimental setup and the diagnostic methods characterizing the workpiece are presented. The weld pool shape was evaluated versus time according to several parameters such as the current intensity value, the distance between the two electrodes, the cathode tip angle or the plasma gas nature. The results show that the depth-to-width ratio alone is not enough to compare the impact of the parameters. The analysis points out the great influence of the current intensity on the increase of the width and depth compared to the influence of the value of the cathode tip angle. The rise of the arc length leads to an increase of the power through a higher arc voltage; nevertheless, for distances of three and five millimeters and a characteristic time of the welding process of one second, this parameter has a weak influence on the energy transferred. The use of helium leads to a bigger volume of the weld pool due to an increase of width and depth.

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Section: Effect Of the Cathode Tip Anglementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration

2017

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“…No programa aqui apresentado, este efeito foi simulado pela introdução de um termo ∆I que é somado ao valor instantâneo da corrente e que leva em consideração a influência de valores anteriormente calculados da corrente de soldagem. Este termo foi definido através de uma expressão recorrente da forma: (8) O coeficiente K Lag depende de um tempo de atraso (t Lag ) definido pelo usuário e é calculado como: (9) onde ∆t é o passo de integração usado. A velocidade de alimentação do arame é selecionada pelo usuário e mantida fixa durante a simulação.…”

Section: Fundamentosunclassified

“…Estas técnicas foram usadas para estudar fenômenos no arco e na poça de fusão [8][9][10][11][12][13][14] e a dissipação de calor na peça [15][16].…”

Section: Introductionunclassified

Um programa de computador para simular alguns aspectos operacionais da soldagem MIG/MAG

Modenesi

Matilde

Cançado³

et al. 2012

Soldag. insp.

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Resumo IntroduçãoA soldagem MIG/MAG é atualmente o mais importante processo industrial para a união de ligas metálicas, particularmente os aços. Este processo apresenta diversas vantagens em relação ao processo de soldagem com eletrodos revestidos, com destaque à sua possibilidade de ser mecanizada ou automatizada de forma relativamente fácil, a sua maior produtividade e maior facilidade de uso. A soldagem MIG/MAG, juntamente com a soldagem com arames tubulares é amplamente utilizada em diferentes ramos da indústria metal-mecânica com destaque para a indústria automobilística, de autopeças e de fabricação de estruturas. Apesar de suas vantagens, o processo MIG/MAG apresenta, quando comparado com a soldagem com eletrodos revestidos e outros processos, uma maior dificuldade de ser ajustado, em parte devido à sua elevada sensibilidade a variações de seus parâmetros operacionais. Neste sentido, um grande número de fatores como, por exemplo, a composição química do eletrodo e seu diâmetro, a composição do gás de proteção, a configuração geométrica do sistema, as características do metal de base e as características do equipamento podem afetar a operação. Esta sensibilidade, em conjunto com diversos fatores externos, incluindo a condição do equipamento de soldagem, pode gerar situações de operação instável, de difícil controle e, muitas vezes, de difícil diagnóstico.O desenvolvimento de modelos matemáticos para simular o comportamento deste processo (e de outros processos de soldagem em geral) é uma alternativa interessante para prever o comportamento do processo, reduzir o número de testes de soldagem para o ajuste das condições de operação e estudar diversos fenômenos importantes do processo.Esta modelagem foi feita inicialmente diretamente a partir de resultados experimentais usando diferentes técnicas estatísticas, sendo esta técnica ainda amplamente usada atualmente para descrever diferentes aspectos do processo com destaque para o

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“…In the most of the previous numerical modelings, an arc flow and electrodes are treated separately and boundary conditions are partly given by using experimental data. [5][6][7][8] Furthermore, the influence of solid-liquid mushy zone 9) in molten anode on the molten pool structure has not been made clear yet so far.…”

Section: Introductionmentioning

confidence: 99%

Computational Simulation of Arc Melting Process with Complex Interactions

et al. 2006

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The real-time computational simulation of arc melting process with considering complex interactions and solid-liquid mushy zone in molten anode has been successfully conducted to provide the fundamental data for highly economical performance of arc melting process. The configuration of molten anode predicted by realistic numerical model shows the quantitative agreement with the experimental data. The effects of sulfur content concentration in molten metal, arc current and cathode vertex angle on the welding structure is discussed in detail. Finally, the heat exchange efficiency and molten cross-sectional area are evaluated under different arc currents and cathode vertex angles for optimum welding process with high efficiency.KEY WORDS: arc melting system; complex interactions; mushy zone; real-time computational simulation.(8) Evaporation, deformation and charge on the molten anode surfaces are neglected for simplicity. (9) Evaporation, melting and deformation on the cathode surface are neglected for simplicity. Under these assumptions, the governing equations for arc and electrodes region are presented as follows.Conservation c Ar c Ar The initial conditions of arc melting process are the steady thermofluid fields of arc without melting anode. Table 1 shows the system configuration and operating conditions. The thermofluid field is solved by SemiImplicit-Method for Pressure Linked Equation (SIMPLE) method 14) using Tri Diagonal-Matrix Algorithm (TDMA). The electromagnetic field is solved by SOR method. In this study, 90 grid points are adopted in both axial and radial directions. The thermodynamic and transport properties of argon, tungsten and stainless steel are given as a function of temperature. 10,[15][16][17][18][19][20][21] The viscosity in the solid-liquid mushy zone is as a function of liquid fraction. Numerical Conditions and Procedures 22) Numerical Results and DiscussionFigures 2(a) and 2(b) show the effect of sulfur content on the temperature fields of arc and molten pool. The steady state of molten pool is obtained approximately 20 s after arc generation. It is found that sulfur content does not affect the arc flow so much even near interface, however, the welding structure changes drastically by sulfur content. In the case of low sulfur content in SUS304 as shown in Fig. 2(a), the molten metal spreads outward. On the other hand, in the case of high sulfur content in SUS304, the molten pool penetrates downward in the core region.Figures 3(a) and 3(b) show the four kinds of driving forces which affects surface flow induced on the molten pool corresponding as shown in Figs. 2(a) and 2(b). In the case of low sulfur content in SUS304, shear force resulting from cathode jet is stronger at the inner molten region but surface tension is stronger at the outer molten region. Then, total driving force shows positive at the inner molten region but negative at the outer one, which induce the outward and inward flows correspondingly. On the other hand, in case of high sulfur content in SUS304, surface tension...

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The effect of the cathode tip angle on the gas tungsten arc welding arc and weld pool: II. The mathematical model for the weld pool

Cited by 45 publications

References 9 publications

Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration

Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration

Um programa de computador para simular alguns aspectos operacionais da soldagem MIG/MAG

Computational Simulation of Arc Melting Process with Complex Interactions

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