Computational Simulation of Arc Melting Process with Complex Interactions

Nishiyama, Hideya; Sawada, Tomohiko; Takana, Hidemasa; Tanaka, Manabu; Ushio, Masao

doi:10.2355/isijinternational.46.705

Cited by 35 publications

(21 citation statements)

References 16 publications

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“…In the first publications, devoted to mathematical simulation of the processes of heat, mass and charge transfer in refractory cathode arcs [2][3][4][5][6][7][8][9][10], arc plasma was assumed to be single-component, i.e. containing atoms and ions of just the shielding gas.…”

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confidence: 99%

Simulation of electric arc with refractory cathode and evaporating anode

Krikent¹,

Krivtsun²,

Demchenko³

2014

The Paton Welding J.

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Equation of convective diffusion of ionized metal vapour in arc plasma, allowing for the difference in coefficients of diffusion of atoms, single-and double-charged metal ions, presence of thermodiffusion flows of metal particles, as well as ion drift in the electric field, was proposed to more precisely define the earlier developed complex model of the processes of energy, mass and charge transfer in the column and anode region of electric arc with refractory cathode and evaporating anode, running in inert gas. Based on the thus precised complex mathematical model, numerical analysis of the influence of diffusion-induced evaporation of anode material (Fe) on heat, gas-dynamic and electromagnetic characteristics of multicomponent plasma of the column and anode region of stationary electric arc with refractory cathode (W) at its running in inert gas (Ar) was performed. An essential influence of metal surface temperature distribution in the region of anode binding of the arc on distribution of temperature and electric current density in near-anode plasma, as well as on distributed and integral characteristics of its thermal impact on evaporating anode surface, is shown. 18 Ref., 12 Figures. K e y w o r d s : electric arc, refractory cathode, evaporating anode, arc column, anode region, multicomponent plasma, metal vapour, diffusion, mathematical simulationElectric arc plasma in inert-gas nonconsumableelectrode welding, as a rule, is multicomponent, as alongside shielding gas particles, it contains atoms and ions of metal vapour coming to the arc gap due to evaporation of anode metal from weld pool surface. Presence of an even small amount of metal component in inert gas arc plasma has an essential influence on its ionization composition, thermodynamic, transport and optical properties. It leads to a significant difference of heat, electromagnetic and gas-dynamic characteristics of plasma in near-anode zone of arc column in nonconsumable-electrode welding from respective characteristics of arc discharge with refractory cathode and nonevaporating, for instance, water-cooled anode. Characteristics of welding arc anode region, determining the conditions of thermal and electromagnetic interaction of the arc with metal being welded and, consequently, nature of its penetration, are also different [1].In the first publications, devoted to mathematical simulation of the processes of heat, mass and charge transfer in refractory cathode arcs [2-10], arc plasma was assumed to be single-component, i.e. containing atoms and ions of just the shielding gas. Such idealization did not incorporate any conditions of running of real welding arcs, and required further improvement of mathematical models of the arc, in order to allow for a number of additional physical factors, related to multicomponent nature of arc plasma. Publications devoted to allowing for evaporation of anode material in simulation of nonconsumableelectrode welding arc, appeared in the world scientific literature comparatively recently [11][12][13]. When describing...

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confidence: 99%

Simulation of electric arc with refractory cathode and evaporating anode

Krikent¹,

Krivtsun²,

Demchenko³

2014

The Paton Welding J.

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“…The following conditions are assumed for this model: (i) the arc plasma was in a state of local temperature equilibrium [3][4][5], (ii) flow was steady/laminar flow, (iii) no account was taken of their self-absorption of radiation from argon and iron. With these assumptions, the following conservation equations were established for mass, movement, energy and electric current as governing equations.…”

Section: Governing Equationmentioning

confidence: 99%

Effects of a constricted nozzle on the arc phenomena in the TIG welding process

Konishi

Shigeta

Tanaka

et al. 2016

Welding International

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Figure 1 is a schematic of the computation model for TIG welding with a constricted nozzle attached. Since, however, in the actual computation model, the arc length is very much smaller than the horizontal dimension of the domain, Figure 1 is drawn so that the domain is readily comprehensible and is not to scale. The computational model, which assumed axial symmetry of the two-dimensional cylindrical coordinate system, comprised the tungsten electrode, gas nozzle, constricted nozzle and base metal. The dimensions of the domain are 37 mm in the axial direction and 25 mm in the radial direction. The diameter of the tungsten electrode was 1.6 mm and the electrode tip angle was 30°. The diameters of the (standard) gas nozzle and constricted nozzle were, respectively, 12.1 and 3.0 mm and the nozzle tip positions were, respectively, 4.0 and 2.5 mm from the base metal surface. The base metal is SUS304 and the arc length was 1.0 mm. The shield gas was argon and this was supplied between the tungsten electrode and constricted nozzle and between the constricted nozzle and the gas nozzle, at the top boundary of the computational domain, at rates of, respectively, 3 and 7 L/min, a total of 10 L/min. The same velocity distribution as in Sansonnens et al.[2] was used. The welding current was DC 80 A and this was introduced from the top boundary of the tungsten electrode.The boundary conditions were that the temperature of the outer edges (top edge, right edge and bottom edge) of the computational domain, excluding the tungsten electrode, nozzles and base metal,

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“…The temperature range is wide, ranging from about 20 000 K in the arc plasma, about 3000 K in the tungsten cathode, about 2000 K in the molten steel, down to room temperature in the surrounding regions [1]. Due to the remarkable progress in computer simulation and observation techniques recently, it has become possible to understand the phenomena in arc welding processes quantitatively [2][3][4]. However, it has not been possible to accurately predict the welding parameters, such as the arc voltage and the weld geometry.…”

Section: Introductionmentioning

confidence: 99%