Editing Inert gas (section)

===Welding===
In gas tungsten [[arc welding]] (GTAW), inert gases are used to shield the tungsten from contamination. It also shields the fluid metal (created from the arc) from the reactive gases in air which can cause porosity in the solidified weld puddle. Inert gases are also used in [[gas metal arc welding]] (GMAW) for welding [[non-ferrous]] metals.<ref>Davis, J.R., ed. ''Corrosion: Understanding the Basics.'' Materials Park, Ohio: ASM International, 2000. 188.</ref> Some gases which are not usually considered inert but which behave like inert gases in all the circumstances likely to be encountered in some use can often be used as a substitute for an inert gas. This is useful when an appropriate pseudo-inert gas can be found which is inexpensive and common. For example, [[carbon dioxide]] is sometimes used in gas mixtures for GMAW because it is not reactive to the weld pool created by arc welding. But it is reactive to the arc. The more carbon dioxide that is added to the inert gas, such as argon, will increase penetration. The amount of carbon dioxide is often determined by what kind of transfer is used in GMAW. The most common in industrial applications is spray arc transfer, and the most commonly used gas mixture for spray arc transfer is 90% argon and 10% carbon dioxide.  In non-industrial applications, short circuit transfer is most commonly used, particularly in the US.  With short circuit transfer, a gas mixture made up of 75% argon and 25% carbon dioxide (referred to as C25) is most often used.  Outside the US, a mixture of 80% argon and 20% carbon dioxide is often used.