Which gas is used for welding?
The inert gas welding process is suitable for many applications. The gas used here protects the welding point from the effects of atmospheric air. Gas-shielded welding is divided into different processes.
In gas-shielded welding, a significant distinction is made between metal shielded arc welding and tungsten shielded arc welding. In gas-shielded metal arc welding, melting wire electrodes are used as filler material, whereas in tungsten gas-shielded welding a non-melting tungsten electrode is used.
Depending on the type of gas used in metal shielding gas welding, a distinction is made between MAG welding – metal active gas welding – and MIG – metal inert gas welding. Tungsten inert gas welding is also divided into TIG – tungsten inert gas welding and WP – tungsten plasma welding.
Metal Active Gas Welding
Active gases are used in MAG welding. These cause a chemical reaction in the weld metal. The active gases are carbon dioxide -MAGC – or mixed gases -MAGM. Welding with MAGC is associated with a large spatter ejection compared to welding with MAGM and with a limited welding power. This is why welding with mixed gases has become widely accepted in practice. The mixed gases used are either
- Argon-carbon dioxideArgon-oxygenArgon-carbon dioxide – oxygen with admixtures of helium
Metal inert gas welding
Metal inert gas welding uses the noble gases argon and helium as well as mixtures of these. In practice, metal inert gas welding is mainly used for welding aluminium, aluminium alloys, copper, titanium and many other non-ferrous metals, as the noble gases do not react with the base and filler materials.
Tungsten Inert Gas Welding
In TIG welding, an inert gas surrounds the electrode and protects it and the workpiece from air. Inert gases such as argon and helium and mixtures of these noble gases are used here. They offer good properties and do not form chemical compounds, so that almost all metals can be joined with them.
Tungsten Plasma Welding
Tungsten plasma welding uses gases consisting of neutral particles, ions and free electrons. For this reason these gases are electrically conductive. A high energy density is achieved by the arc bundling and the plasma flow created during this welding process.
Here, an argon-hydrogen mixture is used for low-alloy steels and chrome-nickel materials and an argon-helium mixture for non-ferrous metals.