Investigation of the thermal state of the welding arc at changes in the polarity of alternating current

Abstract

Investigations were carried out to determine the distribution of the optical density of blackening of the film characterizing the existence of the temperature ‘well’ in TIG welding of aluminium alloys in argon at changes in the polarity of alternating sinusoidal current. The results show that the concentration of the electrons in the arc gap decreases 9.8–11.8 times depending on current polarity. The conditions of stable repeated arc ignition at changes in current polarity were determined.

Keywords:

• WIG-welding
• alternating-current arc
• aluminium alloys
• optical density of the film blackening
• heat flow
• temperature ‘pit’