spg car shoe the laser welding

The predominant constituent of the shield gas is generally an inert gas such as
helium or argon. A shield gas providing a higher ionisation potential is required since the
plasma can deflect or absorb a portion of the laser energy when CO2 lasers are employed.
Helium is therefore often preferred to argon for laser welding, but its lightness is a
disadvantage and it is often combined with argon which is heavier without substantial
alteration of the weld penetration depth. The addition of reactive gases such as oxygen and
carbon dioxide has been shown to have an influence on the weld pool wetting characteristics
and bead smoothness.