Table 2 Special shielding gas mixtures used in arc welding of aluminium and key gas characteristics (based on (Regis 2008))
From: Investigation of weld defects in friction-stir welding and fusion welding of aluminium alloys
Shielding gas mixtures | Resultant positive weld features | Gas characteristics |
|---|---|---|
Argon and helium (80 %) | Improvements in bead profile and fusion | Argon—low cost and better protection as its density is higher than air. |
Argon and chlorine | Significant reduction in porosity & improved process tolerance | Chlorine—extreme toxicity limits its suitability for many applications. |
Argon and Freon | Improved arc stability and weld bead geometry | Argon/Freon mixtures—non-toxic so Freon can substitute chlorine yet obtain similar effects to argon/chlorine mixtures. |
Helium | Greater penetration | Helium—welding Al leads to high levels of ozone. Small amounts of nitric oxide can control ozone formation. |