The answer to this is a resounding no. The tungsten will disintegrate with out any shield gas. There will be no welding happening period. I read the other guys answer and it's so far out to lunch it's a joke. First off its spelled porosity not perosity and this other bullshit about by the the other factors like the weld pool and drying up is proof that he is full of crap. The entire answer is fantasy. By the way it's a weld puddle or in some fields a nugget. Various mixtures of gasses are used and in turn achieve different results. Argon , helium and some case carbon dioxide and trace amounts of oxygen are used in TIG WELDING. The welding is in the staight polarity setup for ferrous metals and AC is used for aluminum due to its abilityto help “wash “ the weld puddle. High frequency current is used for arc stability and non contact starts to reduce tungsten inclusion in the weld. This will show up like a beacon on an xray due to the high density of tungsten.