A B Murphy et al 2009 J. Phys. D: Appl. Phys. 42 194006 doi:10.1088/0022-3727/42/19/194006
A B Murphy1,4, M Tanaka2, K Yamamoto2, S Tashiro2, T Sato3 and J J Lowke1
Show affiliationsThe methods used to model thermal plasmas, including treatments of diffusion in arcs in gas mixtures, are reviewed. The influence of thermophysical properties on the parameters of tungsten–inert-gas (TIG) welding arcs, particularly those that affect the weld pool, is investigated using a two-dimensional model in which the arc, anode and cathode are included self-consistently. The effect of changing each of six thermophysical properties on the characteristics of an argon TIG arc is assessed. The influence of the product of specific heat and mass density is found to be particularly important in determining the arc constriction. By examining the influence of the different properties on the heat flux density, current density and shear stress at the anode, it is concluded that the weld pool depth can be increased by using shielding gases with high specific heat, thermal conductivity and viscosity. The effect of metal vapour on the arc and weld pool properties is assessed. The most important effect of the metal vapour is found to be the increased electrical conductivity at low temperatures, which leads to lower heat flux density and current density at the weld pool, implying a shallower weld pool.
52.77.Fv High-pressure, high-current plasmas (plasma spray, arc welding, etc.)
Issue 19 (7 October 2009)
Received 20 April 2009, in final form 3 July 2009
Published 18 September 2009
A B Murphy et al 2009 J. Phys. D: Appl. Phys. 42 194006
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