Helium-argon mixed gas is a combination of two inert noble gases, helium (He) and argon (Ar), each possessing unique properties that, when blended, offer enhanced performance for specific industrial applications, most notably in welding.
The primary application of helium-argon mixed gas is in welding, particularly Gas Metal Arc Welding (GMAW or MIG) and Gas Tungsten Arc Welding (GTAW or TIG). The specific ratio of helium to argon is chosen based on the material being welded, its thickness, and the desired weld characteristics.
Benefits in welding, such as increased heat input and penetration, improved weld bead appearance and fluidity, reduced porosity, versatility.
Typical Compositions and Their Uses:
Low Helium Content (e.g., 75% Argon - 25% Helium):
Good for welding aluminum workpieces.
Often used for deeper root penetration and reduced porosity in both MIG and TIG welding.
Helium content above 25% may cause arc instability in TIG welding.
Medium to High Helium Content (e.g., 50% Argon - 50% Helium or 25% Argon - 75% Helium):
Ideal for welding thicker materials, especially non-ferrous metals like aluminum, copper, and magnesium, due to increased heat input and penetration.
Can significantly reduce porosity in laser welding of high-temperature alloys, with 50% helium often showing optimal results.
A 70% helium - 30% argon blend is excellent for mechanized aluminum MIG welding where high speeds are desired for material 10 mm or thicker.
Tri-Mixes (Argon-Helium-CO ):
These mixtures are also common, particularly for welding stainless steel and carbon/low-alloy steels.
For example: 90% Helium - 7.5% Argon - 2.5% CO for short-circuiting and spray transfer welding of stainless steel (low CO content helps corrosion resistance and high helium provides heat input).
66% Argon - 26.5% Helium - 7.5% CO for carbon and low-alloy steel welding.
