TIG-welding (Topic: 18009)

Quick consultant:

Recommended material thicknesses

Recommended welding positions

Recommended shielding gases

Joint geometry

Applications

The TIG-welding process.

TIG-welding (Tungsten Inert Gas) or GTAW-welding (Gas Tungsten Arc Welding) uses a permanent non-melting electrode made of tungsten. Filler metal is added separately, which makes the process very flexible. It is also possible to weld without filler material.

The most used power source for TIG-welding generates alternating current (AC). Direct current can be used, but due to high heat generation on the tungsten electrode when DC-EP (electrode positive) welding, that particular polarity is not feasible. In some cases DC-EN (electrode negative) is used, however, this requires special attention before welding, due to the arc's poor oxide cleaning action.

AC TIG-welding usually uses argon as a shielding gas. The process is a multi purpose process, which offers the user great flexibility. By changing the diameter of the tungsten electrode, welding may be performed with a wide range of heat input at different thicknesses. AC TIG-welding is possible with thicknesses down to about 0,5 mm. For larger thicknesses, > 5 mm, AC TIG-welding is less economical compared to MIG-welding due to lower welding speed.

DC TIG-welding with electrode negative is used for welding thicknesses above 4 mm. The negative electrode gives a poor oxide cleaning compared to AC-TIG and MIG, and special cleaning of joint surfaces is necessary. The process usually uses helium shielding gas. This gives a better penetration in thicker sections. DC TIG-welding is applicable for welding thicknesses in the range 0,3ñ12 mm. More and more popular is also pulsed DC TIG-welding, which makes it possible to weld uniform welds with deeper penetration at the same heat input. Pulse frequency is usually in the range 1ñ10 Hz.

References[61,62,68]