Argon

Argon is approximately one and one third times as heavy as air and ten times heavier than helium. Argon, after leaving the torch nozzle, forms a blanket over the weld area. ,Welding grade argon is refined to a minimum purity of 99.95 %. This isacceptable for TIG welding of most metals except for the reactive and refractory metals, for which a minimum purity of 99.997 % is required.

Advantages of argon.

• Smoother, quieter arc action.
• Reduced penetration & cleaning action when welding materials such as aluminium and magnesium.
• Lower cost and greater availability.
• Lower flow rates for good shielding.
• Better cross draft resistance.
• Easier arc starting due to low ionisation potential of 2.52 x 1G- 18J (15 JeV)
• The reduced penetration of an argon shielded arc is particularly helpful in vertical or overhead welding since the tendency for the base metal to sag or run is decreased.