The Lincoln Electric Square wave TIG 200 is a user-friendly welder that allows you to TIG weld metal. TIG stands for (Tungsten Inert Gas). It is sometimes referred to as GTAW (Gas Tungsten Arc Welding). It is a welding process in which an electric arc forms between a consumable wire electrode that is continuously fed out of the welding torch and the metal workpieces. The electric arc heats the metal workpieces and causes them to melt and join.