Though many welders turn to argon as a solid all-rounder, for some jobs there are more specific gas mixes that are a better fit for certain welds and materials.
Here’s a round-up:
Argon - an inert gas that can be used on its own for TIG welding virtually any material and MIG welding aluminium alloys, or as a base for almost all gas mixes.
Carbon dioxide (CO2) – stabilises the arc, increases heat transfer and improves the weld penetration profile. Higher levels of CO2 can help when welding dirty, rusty or primed materials, and when mixed with argon, can produce a better weld for stainless steel. Pure CO2 cannot be used for welding stainless steel.
Oxygen - cannot be used on its own as a shielding gas, but when mixed with argon will help to stabilise the arc. An argon/oxygen mix works well for welds on thin carbon steel, where appearance is a priority (such as for furniture). Argon/oxygen mixtures used to be the “gas of choice” for MAG welding stainless steels, but far better results are easily achievable by using argon/CO2 mixtures.
Nitrogen - is rarely used on its own for shielding, but can be suitable for root shielding applications, and is added to argon for TIG welding Duplex steels.
Helium - provides high thermal conductivity, broadens the weld pool and improves the penetration profile. Though it’s rarely used on its own, it will improve virtually all aspects of a deposited weld when mixed with argon, or in CO2/argon mixes.
Hydrogen - constricts or narrows the arc giving a much more concentrated ‘hot spot’, providing better deposition rates and reducing distortion. Can be mixed with argon for TIG welding austenitic stainless steel.
Are you using the right shielding gas for the job in hand? Check out our
Welding Gas Finder and see.
If you’re struggling with welding defects, check out The Welder’s Toolkit. Your resource for detailed tips and advice from BOC’s welding experts.