Yes, ER70S-6 welding wire absolutely requires gas.
Although ER70S-6 is a solid wire, it belongs to the MIG/MAG system, not the flux-cored system. During welding, it relies entirely on an external shielding gas to isolate it from oxygen and nitrogen in the air, preventing porosity, oxidation, or embrittlement of the weld.
Warning: Welding without a shielding gas is strictly prohibited.
If ER70S-6 welding is performed without a shielding gas, the molten metal will be directly exposed to the air. This will lead to severe porosity, slag inclusions, and cold cracking of the weld metal, resulting in a significant decrease in weld strength.
Recommended Gas Combinations
Based on AWS A5.18 standards and industry practice, the most commonly used gas protection combinations for the ER70S-6 are as follows:
- Gas mixture (most commonly used): 75% Ar + 25% CO₂
This is the "golden combination" for the ER70S-6. Argon provides arc stability, while carbon dioxide provides sufficient oxidizing power to promote the transition of liquid metal and increase the wettability of the weld.
- General: Pure argon (Ar)
It is commonly used in TIG welding or in applications where high weld formation is required. Pure argon gas provides a gentler arc and a more aesthetically pleasing weld shape, but it is more expensive.
Why can't we use other gases?
- Not recommended for use alone.
High spatter: Extremely high spatter rate during pure CO2 welding, resulting in a rough weld appearance.
High heat input: Slow cooling rate, easily leading to brittle heat-affected zone.
Poor applicability: Typically only used for thick plate welding or specific flux-cored wires.
- Argon-Oxygen Mixture (Ar+O₂)
For flat welding only: Excessive oxygen content can lead to unstable arcs and easily cause porosity.
Many limitations: Primarily used for repair welding or special processes; not a standard configuration.
