A unified numerical modeling of stationary tungsten-inert-gas welding process

Abstract

In order to clarify the formative mechanism of weld penetration in an arc welding process, the development of a numerical model of the process is quite useful for understanding quantitative values of the balances of mass, energy, and force in the welding phenomena because there is still lack of experimentally understanding of the quantitative values of them because of the existence of complicated interactive phenomena between the arc plasma and the weld pool. The present article is focused on a stationary tungsten-inert-gas (TIG) welding process for simplification, but the whole region of TIG arc welding, namely, tungsten cathode, arc plasma, workpiece, and weld pool is treated in a unified numerical model, taking into account the close interaction between the arc plasma and the weld pool. Calculations in a steady state are made for stationary TIG welding in an argon atmosphere at a current of 150 A. The anode is assumed to be a stainless steel, SUS304, with its negative temperature coefficient of surface tension. The two-dimensional distributions of temperature and velocity in the whole region of TIG welding process are predicted. The weld-penetration geometry is also predicted. Furthermore, quantitative values of the energy balance for the various plasma and electrode regions are given. The predicted temperatures of the arc plasma and the tungsten-cathode surface are in good agreement with the experiments. There is also approximate agreement of the weld shape with experiment, although there is a difference between the calculated and experimental volumes of the weld. The calculated convective flow in the weld pool is mainly dominated by the drag force of the cathode jet and the Marangoni force as compared with the other two driving forces, namely, the buoyancy force and the electromagnetic force.

A Multiphysics Simulation Approach for Efficient Modeling of Lightning Strike Tests on Aircraft Structures

“…Herein the lightning strike electric arc model is based on the preceding Gas Tungsten Arc (GTA) models available in the literature [19][20][21][22][23][24][25][26][27][28][29]. In general the preceding plasma modelling has assumed the thermal plasma to be in local thermodynamic equilibrium.…”

“…The Lago and Gonzalez et al models [22,23] did not include the cathode region in their simulations, but developed a model to simulate the effect of metal vapour in the plasma column combined to a moving welding torch. The plasma models of Tanaka and Lowke summarized in [25,26] are the most complete, based on the Sansonnens et al model [27], they also include the cathode and anode regions with weld pool formation, and the boundary conditions are directly applied at the external borders with no assumption on the cathode surface temperature.…”

Numerical Analysis of Heat Source Properties of Pulsed Tungsten Inert Gas Arc

“…The governing equations (1)-(6) are solved iteratively by the SIMPLER numerical procedure [4]. The other numerical modeling methods are given in detail in our previous paper [5].…”

Numerical Modeling Of GMAW ARC

“…Many models have been developed to model the heat transfer and fluid flow in the arc plasma for both GTAW [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and GMAW [19][20][21][22][23][24]. Mckelliget and Szekely [1], Choo et al [2] and Goodarzi et al [3] have simulated the arc column by assuming the current density distribution at the cathode surface in GTAW.…”

“…The simplified models [7][8] reduced the computation time to 1% of the original unified model and gave fair results in agreement with experimental results when 0.005-0.01 cm mesh size was chosen around the cathode tip. These simplified models have been used and further developed by many researchers [9][10][11][12][13][14][15][16][17][18] to calculate the heat transfer and fluid flow in the arc column.…”