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Shielding gases

With shielding gases, many parameters of the welding process can be controlled and optimised for specific applications.

The gas or gas mixture must be selected so as to bring about the desired effects.  Possibilities for optimisation include virtually every factor in the welding process.

Physical properties of the gas affect metal transfer, wetting behaviour, depth and form of penetration, welding speed and arc setting.  Gases with low ionisation energies, such as Argon, facilitate arc starting and stabilisation better than those with high ionisation energies, such as Helium.

On the other hand, Helium is a better choice for laser beam welding, where it helps control the plasma and thus the penetration depth.  The dissociation energy of polyatomic components in gas mixtures enhances heat delivery to the base metal by virtue of the energy release in recombination.

The thermal conductivity influences weld forming, weld-pool temperature, degassing and welding speed.  For example, the welding speed and penetration can be markedly increased by the addition of Helium in the MIG and TIG welding of aluminium materials, or by the addition of Hydrogen in the TIG welding of austenetic stainless steels.

Chemical properties influence the metallurgical behaviour as well as the weld surface qualities.  Oxygen, for example, burns off alloy constituents and leads to more fluid weld pools, while Carbon Dioxide adds carbon and gives slightly reinforced welds.  Argon and Helium show metallurgically neutral behaviour and Hydrogen acts as a reducing agent.

Coregas can offer advice on how to maximise your production whilst reducing overall costs, through the correct selection of gases to meet your company's needs.

GMA Welding

Metal inert gas (MIG) and metal active gas (MAG) welding is the most common welding method.  The high productivity offered by this method and the fact that it is simple to automate have contributed to its popularity.

Coregas has a complete range of products for all applications, for standard applications click here for our booklet on gas choices or contact us for more detailed information.

TIG Welding

In contrast to MIG and MAG, which are gas metal-arc processes, in TIG welding the arc burns between a non-melting tungsten electrode and the work piece.  Inert gases, such as Argon or Helium, or mixtures thereof with non-oxidising components, are used to protect the tungsten electrode and the weld pool.

For a handy trouble shooting guide for welding click here.