The basic component of this mixture is argon, to which is added required quantity (%) of one or several additives. It is usually hydrogen (additional symbol is H%, helium (He%), oxygen (S%) or carbon dioxide (C%). FORMING GAS (90% of nitrogen + 10% of hydrogen) is also belongs to this group.
The choice of mixture type depends on welding task. Generally, VARIGON® mixtures are used in order to improve quality and increase welding speed. Such kind of mixture is usually expensive. The main VARIGON® application is MIG-MAG welding and TIG welding of important constructions made of stainless steel, aluminium alloys, etc.
One of the examples of VARIGON® mixtures with helium applications is MIG-MAG welding of stainless steel. For VARIGON® He 30 mixtures the depth of penetration increases twice in comparison with pure argon. It becomes possible to accelerate the speed of welding. Along with it the surface of weld is more plane. There are almost no any spatters.
There are interstices in weld at MIG-MAG welding of aluminium. VARIGON® He 30 and VARIGON® He 50 mixtures reduce the number of interstices that significantly improve the strength of weld.
Another example is VARIGON® mixtures with hydrogen for oxides reduction on the weld at TIG welding of stainless steel. After welding the weld always has oxide (the more oxygen, the darker colour) because there is always some oxygen in pure argon. Mechanical polishing or chemical etching is usually used for oxides removal. In the first case there is a lot of scratches on the surface, in the second there are harmful reagents left on the surface. It is impossible to use these methods, for example, for food purposes. It also can be difficult to access some parts in the construction and remove oxide.
Application of VARIGON® mixtures with hydrogen solves these problems. Usually it is enough 5% of hydrogen in mixture (VARIGON® H5).
VARIGON® mixtures application for weld root protection needs special devices. For independent adjustment of shielding gas flow it is recommended to use special regulator with T-connector and two flowmeters. Gas is injected earlier than welding starts and cut off with delay after welding completion.