Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

When do I use AC or DC for TIG welding?


Frequently Asked Questions

For materials, such as aluminium, which has a tenacious oxide film on the surface, AC power must be employed. By switching between electrode positive and electrode negative polarity at typically fifty times a second, the periods of electrode positive will be sufficient to remove the oxide and clean the surface, Fig.1.

Extracted from an article entitled 'Let's get technical - choosing an arc welding power source' by W Lucas and G Melton, published in Welding & Metal Fabrication, Vol.67, No.4, May 1999, pp.18-21. (Publishers - dmg BusinessMedia Ltd, Redhill, Surrey, UK -

For more information, please contact us.

For more information please email: