Tungsten cathode-arc plasma-weld pool interaction in the magnetically rotated or deflected gas tungsten arc welding configuration

摘要

The gas tungsten arc welding (GTAW) arc and weld pool are theoretically and experimentally determined to be rotated or deflected with an extra magnetic field (EMF). The configurations of variational GTAW with respectively extra axial magnetic field (EAMF) and extra transverse magnetic field (ETMF) are studied for their gradually increasing usage rate in magnetic control welding fields. Taking advantage of mathematical methode, we present the calculated results of temperature fields, flow fields, pressure fields in GTAW and with EMF for comparison. Especially for the explanation to the different flow patterns in the weld pool between GTAW and with EMF, the shear stresses and temperature distributions on the anode top surface of them are highlighted. The results of heat flux and current flux on the cathode and anode surfaces are calculated to analyze the heat transfer conditions between the arc and electrodes. Otherwise the metal vapour behaviours are also discussed on account of their different distributions in the arc with EMFs: in the EAMF, the metal vapour in the arc generates like a fountain; in the ETMF, the metal vapour gathers to one side in the deflected section and its mass fraction reaches 1.15%, hence the impact on the arc cannot be neglected any more. The increasing mixture conductivity of metal vapour and shielding gas in the low temperature region makes the current path on the anode top surface in GTAW to expand when even applying a weak ETMF (B = 0.001T). (C) 2018 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.