Numerical Analysis of Metal Vapor Behavior with Multi-diffusion System in TIG Welding of Stainless Steel

Yamamoto, K.; Tanaka, Manabu; Tashiro, Shinichi; Nakata, Kohei; Yamazaki, Kei; Yamamoto, Eri; Suzuki, Keiichi; Murphy, Anthony B.

doi:10.2207/qjjws.27.4s

Cited by 13 publications

(6 citation statements)

References 13 publications

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“…Iron vapour is swept upward without being dispersed due to the flow rate being increased by the constricted nozzle. It is thought that the decrease in arc plasma temperature caused by the presence of iron vapour is controlled due to this [6,10]. Figure 5 shows the thermal flux distribution at the base metal surface.…”

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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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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“…The simulation model employed in this study consists of a GTA welding model [8] and a fume formation model. Additionally, a GMA welding model taking account of metal transfer process has also been developed for coupling that with the fume formation model.…”

Section: Simulation Modelmentioning

confidence: 99%

“…n 1 is the number density of iron atoms. is a dimensionless surface energy expressed by equation (8).…”

Section: Homogeneous Nucleation Model Of Primary Particlementioning

confidence: 99%

“…Tanaka and Lowke quantitatively showed its formation mechanism using a unified numerical model taking account of thermal and dynamic interactions between the arc and the weld pool [7]. Furthermore, Yamamoto et al and Mori et al improved this model and additionally discussed the evaporation of the metal vapour from the weld pool and its diffusion in the arc [8,9]. However, the fume formation mechanism from the metal vapour has not been reported in arc welding.…”

Section: Introductionmentioning

confidence: 99%

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Numerical analysis of fume formation mechanism in arc welding

Tashiro

Zeniya

Yamamoto

et al. 2010

J. Phys. D: Appl. Phys.

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In order to clarify the fume formation mechanism in arc welding, a quantitative investigation based on the knowledge of interaction among the electrode, arc and weld pool is indispensable. A fume formation model consisting of a heterogeneous condensation model, a homogeneous nucleation model and a coagulation model has been developed and coupled with the GTA or GMA welding model. A series of processes from evaporation of metal vapour to fume formation from the metal vapour was totally investigated by employing this simulation model. The aim of this paper is to visualize the fume formation process and clarify the fume formation mechanism theoretically through a numerical analysis. Furthermore, the reliability of the simulation model was also evaluated through a comparison of the simulation result with the experimental result. As a result, it was found that the size of the secondary particles consisting of small particles with a size of several tens of nanometres reached 300 nm at maximum and the secondary particle was in a U-shaped chain form in helium GTA welding. Furthermore, it was also clarified that most part of the fume was produced in the downstream region of the arc originating from the metal vapour evaporated mainly from the droplet in argon GMA welding. The fume was constituted by particles with a size of several tens of nanometres and had similar characteristics to that of GTA welding. On the other hand, if the metal transfer becomes unstable and the metal vapour near the droplet diffuses directly towards the surroundings of the arc not getting into the plasma flow, the size of the particles reaches several hundred nanometres.

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“…The measurements and modelling of Gonzalez et al [10] showed that the presence of iron vapour resulted in a reduction of the temperature of an argon arc by about 1000 K within 2 mm of the anode in a 20 mm-long arc with 90 A arc current. Computational modelling of the metal vapours produced from stainless steel workpieces for argon and helium arcs likewise predicted that the vapour would remain confined to the region close to the anode workpiece [11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the effects and transport mechanisms of iron vapour in tungsten inert-gas welding in argon

Xiang¹,

Park²,

Tanaka³

et al. 2019

J. Phys. D: Appl. Phys.

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Tungsten inert-gas (TIG) welding uses an electric arc between a tungsten cathode and a metal anode to partially melt the anode workpiece, forming a weld pool. Metal vapour emanating from the weld pool has important effects on the arc welding process. An axisymmetric computational model of the arc and weld pool is used to examine the transport and influence of iron vapour on an argon arc plasma. In contrast to previous studies that use approximate and incomplete treatments of diffusion, the present model incorporates the combined diffusion coefficient method, which takes into account all important driving forces. The influence of metal vapour is first examined for an arc current of 400 A. Metal vapour is predicted to be present in high concentrations above the anode and near the cathode tip, and in a lower concentration in the arc column. The presence of metal vapour in the arc is found to lead to a substantial reduction in arc temperature (up to 1600 K) and current density, resulting in a significant decrease in the weld pool depth and volume. It is shown that ordinary diffusion leads to iron vapour transport upward from the anode region along the arc fringes and into the recirculating convective flow, which carries the iron vapour to the cathode region. Here the upward diffusion driven by the electric field and temperature gradient traps the iron vapour below the cathode tip, leading to a high concentration in this region. The influence of arc current is investigated in the range from 150 to 400 A. The results obtained for standard welding currents of 150, 200 and 250 A also predict significant concentrations of iron vapour in the arc, with the concentration increasing with current in the arc column and near the anode. The concentration near the cathode tip is lower at 400 A because the temperature and electric field diffusion coefficients are lower at the higher temperatures present near the cathode. Spectroscopic measurements of atomic chromium emission for argon TIG welding of a chromium anode are presented and compared to predictions of the code. The measurements show the presence of metal vapour in both the cathode and anode regions, in agreement with the model.

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Numerical Analysis of Metal Vapor Behavior with Multi-diffusion System in TIG Welding of Stainless Steel

Cited by 13 publications

References 13 publications

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

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

Numerical analysis of fume formation mechanism in arc welding

Numerical study of the effects and transport mechanisms of iron vapour in tungsten inert-gas welding in argon

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