Tungsten inert gas welding (TIG welding) is a protective gas welding process and is one of the fusion welding processes. It is used wherever the highest quality and spatter-free weld seams are important. TIG welding is suitable for stainless steel, aluminum and nickel alloys as well as thin sheets of aluminum and stainless steel. Applications can be found in pipeline and tank construction, in portal construction or in the aerospace industry.
TIG WELDING: HOW IT WORKS
With TIG welding, the required current is supplied via a tungsten electrode that is temperature-resistant and does not melt. An arc arises from this electrode, which heats and liquefies the material. There is a protective gas nozzle around the electrode. This protects the heated material from chemical reactions with the ambient air. The noble gases argon, helium or mixtures thereof are used for this. The inert, i.e. non-reactive gases prevent chemical reactions with the molten pool and the heated material. This ensures high quality welds.
Because the tungsten electrode does not melt, the filler material is added manually or mechanically using an external wire feeder during TIG welding.
THE TUNGSTEN ELECTRODE
The tungsten electrode is the heart of TIG welding. At 3,380 degrees Celsius, tungsten has the highest melting point of all pure metals in the periodic table. As a result, the electrode does not melt while an arc is emanating from it, which heats and liquefies the material. The electrodes are manufactured using a sintering process. To improve their properties, they can be alloyed with oxidic additives. Depending on the alloy, the electrodes are marked in different colors:
/ Smooth spherical electrode surface
/ Ignition problems with direct current
/ Low current carrying capacity
/ Suitable for all materials
/ Very good ignition properties
/ Longer service life than WT or WC electrodes
/ Suitable for all materials
/ Very good ignition properties
/ Longer service life than tungsten thorium or tungsten cerium oxide electrodes
/ Poor ignition properties
ADVANTAGES OF TIG WELDING
TIG WELDING: HOW IT WORKS
With TIG welding, the required current is supplied via a tungsten electrode that is temperature-resistant and does not melt. An arc arises from this electrode, which heats and liquefies the material. There is a protective gas nozzle around the electrode. This protects the heated material from chemical reactions with the ambient air. The noble gases argon, helium or mixtures thereof are used for this. The inert, i.e. non-reactive gases prevent chemical reactions with the molten pool and the heated material. This ensures high quality welds.
Because the tungsten electrode does not melt, the filler material is added manually or mechanically using an external wire feeder during TIG welding.
THE TUNGSTEN ELECTRODE
The tungsten electrode is the heart of TIG welding. At 3,380 degrees Celsius, tungsten has the highest melting point of all pure metals in the periodic table. As a result, the electrode does not melt while an arc is emanating from it, which heats and liquefies the material. The electrodes are manufactured using a sintering process. To improve their properties, they can be alloyed with oxidic additives. Depending on the alloy, the electrodes are marked in different colors:
- PURE TUNGSTEN (WP) (GREEN):
/ Smooth spherical electrode surface
/ Ignition problems with direct current
/ Low current carrying capacity
- RARE OXIDE (WS2) (TURQUOISE):
/ Suitable for all materials
/ Very good ignition properties
/ Longer service life than WT or WC electrodes
- CEROXIDE (WC 20) (GRAY):
/ Suitable for all materials
/ Very good ignition properties
- LANTHANOXIDE (WL 20) (BLUE):
/ Longer service life than tungsten thorium or tungsten cerium oxide electrodes
/ Poor ignition properties
ADVANTAGES OF TIG WELDING
- No formation of welding spatter
- Optically high quality welds
- All welding positions are possible
- Very high weld quality
DISADVANTAGES OF TIG WELDING
- Requires high skill
- Low welding speeds
- Rust must be removed when preparing the weld
- Not suitable for large workpiece thicknesses
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