In TIG welding (tungsten argon arc welding), it is true that gas mixtures can be used, and in some specific cases, better welding results can be achieved by using a mixture of shielding gases other than argon. However, whether to use a gas mixture and what ratio to choose needs to be considered based on the welding material, welding process requirements and cost factors.
Common gas mixture types
1.Ar+H₂
Typical ratio: Hydrogen content is usually 2%~10%
Merit:
Increase arc temperature and heat input, suitable for welding stainless steel and nickel alloys;
Improve weld wettability and make the weld bead smoother;
It has reducing properties and reduces oxidation.
Note:
It is not suitable for welding materials such as aluminum and titanium, which can easily lead to porosity;
The hydrogen content should not be too high to prevent weld cracks or metal embrittlement.
2.Ar+He
Typical ratio: helium proportion can be from 25%~75%
Merit:
Enhance arc energy and improve penetration depth;
It is suitable for high thermal conductivity materials such as thick plates, copper, and aluminum;
Improved welding speed.
Shortcoming:
High cost;
The point arc is slightly worse than pure argon and requires a higher arcing voltage.
3.Ar+N₂
For partial austenitic stainless steel and duplex stainless steel welding;
Enhance melt pool fluidity, but use it less and require careful control of nitrogen content.
When To Use Gas Mixtures?
When welding thick plates and requiring higher heat and penetration depth, helium mixture can be used;
When welding stainless steel and pursuing a smoother weld surface, hydrogen can be added in moderation;
When higher welding speeds are required or in special processes such as automated welding, gas ratios can be customized according to requirements.
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