Welding

Which Gas for Tig Welding? The Best Options

Which Gas for Tig Welding

The most commonly used gases for TIG welding are argon and helium, either individually or in a mixture.

Pure helium is not commonly used but is often added to argon.

Hydrogen can be added to argon for high welding speed and penetration, but is limited to specific materials.

Nitrogen can be added for welding duplex stainless steel.

Small quantities of oxygen and carbon dioxide can be added for desired weld properties.

The most commonly used mixture for TIG welding is 75% helium and 25% argon, while another common mixture is 95% argon and 5% hydrogen.

Argon blended with helium or hydrogen is recommended for different types of stainless steel.

MIG welding requires different gas mixtures compared to TIG welding.

Did You Know?

1. Tig welding, also known as Gas Tungsten Arc Welding (GTAW), requires the use of an inert gas to protect the weld from atmospheric contamination.

2. The most commonly used gas for Tig welding is argon. It is preferred due to its excellent ability to protect the weld pool, its non-reactive nature, and its wide availability.

3. Pure argon gas is primarily used for welding non-ferrous metals such as aluminum, copper, and magnesium. It helps to prevent oxidation and produces high-quality welds.

4. In certain applications, a blend of argon and helium gases is used for Tig welding. This mixture allows for higher heat conductivity and increased arc stability, making it suitable for welding materials with higher heat input requirements, like stainless steel.

5. Helium gas can also be used as a standalone shielding gas for Tig welding. Although less common, it is sometimes chosen for its higher heat input, which is beneficial for welding thick materials or where faster travel speeds are desired.

Commonly Used Shielding Gases For Tig Welding

When it comes to TIG welding, the choice of shielding gas plays a vital role in achieving high-quality welds. The most commonly used shielding gases for TIG welding are argon and helium, either individually or as a mixture.

Argon, being an inert gas, provides excellent protection for the weld area by preventing the atmospheric contaminants from interfering with the welding process.

On the other hand, helium is known for its high heat capacity and thermal conductivity. Although pure helium is not commonly used in manual TIG applications, it is often used as an additive to argon. The addition of helium enhances the heat input and can improve the overall performance of the weld.

  • Argon is commonly used as a shielding gas in TIG welding.
  • Helium can be used as an additive to improve the performance of the weld.

Limitations And Benefits Of Different Additives In Shielding Gases

In addition to helium, other additives like hydrogen, nitrogen, oxygen, and carbon dioxide can be used in different concentrations to fine-tune the shielding gas for specific welding requirements.

Hydrogen is often used as an additive to argon for its high welding speed and deep penetration capabilities. However, it is important to note that hydrogen is limited to welding austenitic stainless steel and nickel alloys. Using an argon/hydrogen shielding gas mixture for other materials such as aluminum, mild steel, martensitic, ferritic, or duplex stainless steels, or alloy steels can lead to porosity and hydrogen cracking.

Nitrogen can be added to the argon blend for welding duplex or super-duplex stainless steel. This combination helps to improve the mechanical properties of the weld and enhances its resistance to corrosion.

Small quantities of oxygen and carbon dioxide can also be added to the shielding gas mixture to achieve desired weld properties. However, it is essential to carefully control the amount of oxygen and carbon dioxide, as excessive amounts can negatively impact the quality of the weld.

Shielding Gas Mixtures For Specific Materials And Alloys

To achieve optimal results, specific shielding gas mixtures are required for different materials and alloys.

For TIG welding, the most commonly used mixture is 75% helium and 25% argon. This blend provides good arc stability, heat input, and overall control.

Another widely used mixture is 95% argon and 5% hydrogen, which is particularly suitable for welding austenitic stainless steels. The addition of hydrogen provides deeper penetration and improved welding speed.

In the case of welding duplex, super duplex, austenitic stainless steels, and copper, a blend of 98% argon and 2% nitrogen is recommended. This mixture ensures good arc stability while maintaining the mechanical properties of the weld.

It is important to note that the use of helium should be avoided for thin stainless steel, as it can cause overheating and distortion.

  • 75% helium and 25% argon – good arc stability, heat input, and control
  • 95% argon and 5% hydrogen – suitable for welding austenitic stainless steels, deeper penetration and improved speed
  • 98% argon and 2% nitrogen – recommended for welding duplex, super duplex, austenitic stainless steels, and copper to maintain weld properties
  • Avoid using helium for thin stainless steel to prevent overheating and distortion.

Differences Between Shielding Gases For Mig And Tig Welding

While TIG welding relies on argon-based shielding gases, MIG welding requires a different approach. In MIG welding, a 75% argon and 25% carbon dioxide mixture, known as “75/25 MIG gas,” or 100% carbon dioxide is commonly used. These mixtures provide excellent arc stability and good penetration for welding carbon steel.

For MIG welding aluminum, pure argon is the preferred choice. Aluminum is highly reactive, and using a pure argon shielding gas ensures proper protection from atmospheric contamination.

It is critical to note that using a 75/25 MIG gas for TIG welding is not recommended. The carbon dioxide in the mixture conducts electricity and can lead to poor weld quality. Moreover, it can cause the tungsten electrode to burn, resulting in shorter electrode lifespan.

Recommended Shielding Gases For Different Types Of Welding

To achieve effective TIG welds, it is recommended to use plain argon or an argon and helium mixture.

  • For carbon steel, straight argon or Argon/Helium (Ar/He) mixtures work best.
  • These gas compositions provide optimal control and stability during the welding process.

When it comes to stainless steel, Ar/He mixtures or pure argon are recommended.

  • However, for thick austenitic stainless steel, adding up to 5% hydrogen to the argon shielding gas can improve the penetration and overall quality of the weld.

The choice of shielding gas plays a critical role in TIG welding. It is necessary to consider the requirements of the material being welded and to use the appropriate gas mixture to achieve the desired results. By understanding the limitations and benefits of different additives and gas mixtures, welders can ensure high-quality welds with excellent mechanical properties and corrosion resistance.

  • Key points:
  • Use plain argon or argon and helium mixture for effective TIG welds.
  • For carbon steel, straight argon or Argon/Helium (Ar/He) mixtures are recommended.
  • For stainless steel, Ar/He mixtures or pure argon are recommended.
  • Adding up to 5% hydrogen to the argon shielding gas can improve weld quality for thick austenitic stainless steel.

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Frequently Asked Questions

Is TIG welding CO2 or argon?

TIG welding uses pure Argon gas for a clean weld without oxidation. On the other hand, MIG welding utilizes a combination of Argon and CO2 gas to achieve higher penetration and heat. The gas in MIG welding serves the purpose of shielding and protecting the wire, arc, and molten weld metal from the atmosphere.

Can I use the same gas for MIG and TIG welding?

No, you cannot use the same gas for MIG and TIG welding. MIG uses an active gas, also known as semi-inert gas, while TIG requires an inert gas. Active gases are used in MIG welding to help stabilize the electric arc and shield the weld pool from outside contaminants. In contrast, inert gases used in TIG welding prevent oxidation and contamination of the weld. Therefore, it is essential to choose the appropriate gas based on the specific welding process being used.

Can you use CO2 for TIG welding?

No, CO2 cannot be used for TIG welding. TIG welding relies on the use of 100% Argon gas as a shielding gas. This is because CO2 will have a negative impact on the tungsten electrode, which is non-consumable in TIG welding. Unlike in MIG welding, where the weld pool is fed by a consumable electrode, TIG welding requires precise control of the weld pool by hand, making it incompatible with CO2 mixtures.

Which gas is not used in TIG welding?

One gas that is not used in TIG welding is oxygen. Although different gases such as helium, nitrogen, and hydrogen can be added to modify arc characteristics, the use of oxygen in the gas mixture should be avoided. Oxygen can lead to poor quality TIG welds that are weak and porous, affecting the overall integrity of the welding process. Similarly, carbon dioxide should also be excluded from the gas mixture to ensure optimal results in TIG welding.

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