Effects of evaporation-determined model of arc-cathode coupling on weld pool formation in GMAW process simulation

Simplified surface heat source distribution for GMAW process simulation based on the EDACC principle

“…It should be noted that in this model, the surface flows cannot be considered accurate, as no Marangoni convection was considered. Also visible is, as was already pointed out in [12], a slight local maximum of heat flux close to the center of the attachment, where the influence of the droplets modifies the weld pool surface temperature. Additionally, it can be seen that the considered weighting factor limits the maximum surface temperature to T W, max ≈ 2700 (K) and the EDACC model causes a very even distribution of the surface temperature over the whole area of attachment.…”

“…3, the resulting heat flux and surface temperature distributions are shown. It can be seen that the maximum characteristic of the heat flux on the weld pool front is apparent, just as in [12]; however, also a local maximum of the heat flux towards the tail of the weld pool appeared, which has its reason in the consideration in the smooth distribution of T plasma, bulk , while in [12], the distribution was flat and confined to a specific radius. It should be noted that in this model, the surface flows cannot be considered accurate, as no Marangoni convection was considered.…”

“…The results for the heat source have been exemplified for a typical steady-state weld pool simulation, based in the hydrodynamics model shown in [12]. The process parameters under consideration were U PowerSource = 26.9 (V) and I Arc = 200 (A), for a weld pool width of 10.9 (mm), i.e.…”

“…A thorough validation of the presented heat source model in terms of cross-section comparisons can not yet be presented. A first initial spot sample evaluation with a comparison of the EDACC model and with a Gaussian heat source was presented in [12], However, as was discussed there also, the new EDACC formulation gives results, at least for the surface temperature field, which are not physically inconsistent, i.e., where boiling temperature is not exceeded. Another argument in favor of the EDACC model in terms of physical consistency is that when applying the Gaussian heat source, the forces due to the Marangoni effect are often overestimated due to the much larger surface temperatures and resulting temperature gradients, as well as uncertainties on the value of the surface tension which is very sensitive to the chemical composition (see [16]).…”

“…It follows that there is a demand for a method to consider the cathode sheath processes more accurately. In [11], a model for the evaporation-determined arc-cathode coupling in GMAW (EDACC) was presented and its effects were investigated in [12]. In this model, the heat deposition from the plasma to the weld pool is realized by the arc-cathode interaction in the cathode layer and heat transfer by heat conduction plays only a minor role.…”