Tungsten inert Gauze (TIG) welding is a manner used to accompany or rebuild metal. The inert, or chemically unreactive, gases used as shielding gases are pure argon, pure helium or a alloy of the two.
Mixture
Pure argon produces a welding arc -- a luminous discharge between the gratuity of a welding rod and a metal surface -- that is elementary to begin and steady.
Argon
For welding automotive bodywork, a mixture of 90 percent argon and 5 percent carbon dioxide, or 80 percent argon and 20 percent carbon dioxide are best. These mixtures improve metal transfer and permit the creation of a weld that is smooth, clean and free from spattering.Pure helium, but, flows faster and penetrates too than argon; by mixing the gases, you can grip avail of the desirable properties of both.