Kjell-Arne Persson

Abstract

TIG welding has a number of very attracting features:

• No spatter
• Low surface oxidation
• High weld quality
• A heat source that is controlled independent of the filler metal addition.
• Low investment cost

Some of the drawbacks usually associated with conventional TIG welding are low welding speed, thermal distortion, rather low and sometimes varying penetration depth, difficult to robotize, disturbance from HF start, the arc is sensitive to magnetic deflection, unstable arc at very low currents. To overcome these drawbacks process modifications have been developed. Process and equipment modifications are described and explained. Some modifications have existed for many years while some are more recently developed. Examples of trademarks and performance are given. With arc constriction the energy density can be increased and the TIG process starts to compete in penetration depth, travel speed, and lower heat input with processes such as plasma welding and laser brazing. TIG brazing of zinc coated steel sheets can be performed with travel speeds as high as 5m/min. Plate thickness ranges from 0.1mm to 8mm can be TIG welded in one pass. With hot wire TIG deposition rates up to about 5kg/h can be utilized.