Heat Exchange and Voltage Drop in Welding Arc Column

Abstract

The phenomena that are involved in arc welding processes are not well known, due to the difficulty in studying them experimentally, as a consequence of the complexity and interdependence of all the physical factors involved. One of the unclear issues is the electrical resistance of the arc column (composed of bulk plasma and presheath regions). Thus, the objective of this this was to investigate experimentally the relationship between heat exchange in the arc environment and the voltage drop as a means of understanding the nature of the resistance to the electrical current along the arc column. The observation of this phenomenon was performed through arc voltage analysis, using current as the input to the system. A pulsed Gas-Shielded Tungsten Arc Welding (GTAW) arc in an artificially created quasi-adiabatic environment was used and its arc voltage was compared with the voltage in an open environment. A heat-sinking environment was also used to validate the results. Evidence showed that, on the contrary to what has been sometimes mentioned in literature, the arc should not be treated as a pure ohmic electrical resistance and the voltage drop in the arc column would be significantly related to the electrical potential difference demanded to maintain the arc during atom deionization and reionization processes in the region.