1. the advantages of Ar+He argon arc combustion is very stable, minimal splash. The advantages of helium are high arc temperature, large heat input of base metal and fast welding speed.

The advantages of both can be obtained by adding a certain amount of helium in argon matrix.

When welding large thickness aluminum and aluminum alloy, Ar+He mixed gas can improve weld penetration, reduce porosity and increase productivity. When the plate thickness is 10-20mm, the volume fraction of He is 50%. When the plate thickness is greater than 20mm, He with volume fraction of 75% ~ 90% is added.

When welding copper and copper alloy, Ar+He mixed gas can improve the wettability and quality of weld. The proportion of He is generally 50% to 75%(volume fraction).

2. Adding H2 into argon can increase arc temperature and heat input of base metal. For example, when TIG arc or plasma arc welding stainless steel, in order to improve the welding speed, the volume fraction of 4%-8% H2 is often added in argon.

The reducibility of Ar+H2 gas mixture can be used to weld nickel and its alloys to suppress and eliminate CO porosity in nickel welds. But the added H2 content (volume fraction) must be less than 6%, otherwise hydrogen pores will be created.