Ⅰ. Differences in the Function and Basis of Protective Gases

 

Characteristics of pure argon gas

 

Inert gas, which does not undergo chemical reactions with the molten pool, is suitable for welding active metals such as aluminum (like 5052 alloy), magnesium, and titanium.

The arc is stable with little spatter, but the penetration depth is relatively shallow (about 20%-30% shallower than the mixed gas), making it suitable for thin plate welding (<3mm).

The cost is relatively high (industrial-grade argon gas is about 30-50 yuan per cubic meter), but there is no need to frequently adjust the parameters.

 

Common types of mixed gas

-AR +CO₂ (commonly used ratio: 75%/25%) : Increase the penetration depth of carbon steel (by 15%-25%). The higher the CO₂ content, the greater the splashing, but the cost is lower (about 20-35 yuan per cubic meter).

-AR +O₂ (1%-5% O₂) : Improves the wettability of stainless steel and reduces undercut defects.

-Ar +He: Used in high thermal conductivity materials (such as copper), it increases heat input (when helium accounts for 30%, thermal efficiency increases by 40%).

 

Ⅱ. Key Performance Comparison and Selection Suggestions

Welding quality

Pure argon gas welds have a smoother surface, but mixed gases can reduce porosity (for example, Ar+CO₂ can lower the porosity of carbon steel by more than 50%).

The mixed gas has higher technical requirements for welders and the proportion needs to be adjusted according to the material (for example, for 304 stainless steel, Ar+2%O₂is recommended).

Economy and efficiency

The mixed gas can increase the welding speed (for example, Ar+CO₂ is 10%-15% more efficient than pure argon), and is suitable for mass production.

Pure argon gas has a high single cost, but the equipment wear and tear is small (the nozzle life is extended by 20%).

 

3.Typical application scenarios

 

- Pure argon: Aerospace titanium alloy components, food-grade stainless steel pipes.

- Mixture: Automotive chassis (Ar+15%CO₂), thick plate steel structure (Ar+He).

 

Ⅲ. Extended Question: How to Choose Gases?

 

Reference standard: AWS (American Welding Society) recommends using Ar+20%CO₂ for low-carbon steel and pure argon for aluminum-magnesium alloys. Testing and verification: First, conduct a test weld to assess spatter and penetration depth, and then use it in batches.