Gas is used in welding to protect the weld from atmospheric gases and to affect the appearance and heat produced by the weld. Some common gases used in welding include:
Argon: An inert gas used in Tungsten Inert Gas (TIG) welding to shield the weld area
Helium: An inert gas used in TIG welding to shield the weld area
Carbon dioxide: Used in MIG welding, often in a 75/25 mix with argon