# Argon-carbon dioxide shielding mixtures

Composition, transfer-mode selection, delivery controls and handling limits for argon–carbon dioxide welding gases.

Reviewed: 2026-11-01

Tags: consumables, gases, welding

Linde **CORGON 18** specifies **18% CO₂, balance argon**, by ideal volume fraction (equivalent to mole fraction), **M21-ArC-18**. Air Liquide France **ARCAL Speed** specifies **8% ±0.8% CO₂, balance argon**, **M20-ArC-8**, with **40 ppm v/v water at 5 bar**, **50 ppm v/v oxygen** and **200 ppm v/v nitrogen** as limits. Match the blend to the wire, transfer mode and welding procedure. [Linde, *CORGON 18 Product Data Sheet*](https://static.prd.echannel.linde.com/wcsstore/DE_REC_Industrial_Gas_Store/datasheets/pds/corgon_18.pdf) [Air Liquide, *ARCAL Speed Product Sheet*](https://fr.airliquide.com/product-assets/e/5/0/6/e506d23cb56bb91a137f337ef469ae700fccfabb_ARCAL%E2%84%A2_Speed_fr_FR_v1.5.pdf)

## Identity and function

Carbon dioxide is an active component in argon–CO₂ shielding. The MAG designation reflects the active blend even where the equipment is called MIG. [Linde, *MIG/MAG Welding*](https://www.linde-gas.nl/shop/en/nl-ig/mig-mag-lassen)

Gas choice affects arc behavior and weld metallurgy as well as protection. Linde identifies penetration, bead shape, travel speed and mechanical properties among the selection considerations, and specifically warns that carbon dioxide in stainless-steel MAG shielding can compromise weld-metal corrosion resistance. A gas that produces an apparently stable arc is therefore not automatically suitable for the required weld properties. [Linde, *Shielding Gases*](https://www.linde-gas.com/products-and-services/gases/shielding-gases).

## Composition, grade and designation

The German CORGON 18 sheet is dated **7 August 2017** and specifies **DIN EN ISO 14175 M21-ArC-18**. [Linde, *CORGON 18 Product Data Sheet*](https://static.prd.echannel.linde.com/wcsstore/DE_REC_Industrial_Gas_Store/datasheets/pds/corgon_18.pdf)

The French ARCAL Speed sheet identifies **EN ISO 14175-M20-ArC-8** and carries **23 December 2024, V1.5**. Confirm the applicable product sheet when ordering outside that market. [Air Liquide, *ARCAL Speed Product Sheet*](https://fr.airliquide.com/product-assets/e/5/0/6/e506d23cb56bb91a137f337ef469ae700fccfabb_ARCAL%E2%84%A2_Speed_fr_FR_v1.5.pdf)

Airgas’s **ACLSPEED300XLT** listing identifies its ARCAL Reference Line and states conformance against specified AWS A5.32 and ISO 14175 editions. Verify grade, composition, connection and the qualified procedure for the actual supply. [Airgas, *ARCAL Speed, ACLSPEED300XLT*](https://www.airgas.com/p/ACLSPEED300XLT)

## Transfer modes and material boundaries

For mild-steel applications, Miller describes 75% argon/25% carbon dioxide, commonly called C-25, as providing favorable arc and bead characteristics. It identifies 90% argon/10% carbon dioxide, C-10, as an option for spray transfer. These names encode different mixtures, not interchangeable settings on a regulator. Miller also directs users to the filler-metal manufacturer's gas recommendations. [Miller, *What Type of Gas Is Best for MIG Welding in DIY Applications?*, 30 September 2025](https://www.millerwelds.com/en-us/resources/knowledge-hub/mig-welding/how-to/what-type-of-gas-is-best-for-mig-welding-in-diy-applications).

Transfer depends jointly on gas, voltage and current. Miller's pulsed-MIG guide says carbon-steel spray and pulsed transfer typically require at least 80% argon and identifies 90/10 as common. Pulsed spray additionally requires a capable power source: peak current transfers droplets while lower background current maintains the arc. An argon percentage alone is not a universal transition-current recipe or assurance that a selected waveform will operate correctly. [Miller, *Guide to Pulsed MIG Welding in Manufacturing*, 2 February 2024](https://www.millerwelds.com/en-US/resources/knowledge-hub/mig-welding/how-to/guide-to-pulsed-mig-welding-in-manufacturing).

Wire construction changes the boundary. Miller separately notes that carbon-steel spray applications may use mixtures down to 75% argon with some metal-cored wires, compared with its 80% guidance for solid wire. It recommends different gas selections for stainless steel and aluminum and points to each wire's specification sheet. Do not apply the solid-wire rule to every cored wire, or substitute a carbon-steel mixture merely because it is available. [Miller, *10 Welding Operation Mistakes and How to Solve Them*, shielding-gas section](https://www.millerwelds.com/fr-ca/resources/knowledge-hub/industrial-welding/top-10-mistakes-in-running-a-welding-operation-and-simple-ways-to-solve-them).

For a bounded stainless example, Miller describes 98% argon/2% carbon dioxide as typical for pulsed MIG, with its guide limiting carbon dioxide to no more than 5% to avoid sensitization. This is guidance for the discussed process, not blanket permission for all stainless grades, wires or corrosion-service requirements. Aluminum uses inert argon or argon/helium shielding in that guide; carbon-dioxide blends are excluded. [Miller, *Guide to Pulsed MIG Welding in Manufacturing*](https://www.millerwelds.com/en-US/resources/knowledge-hub/mig-welding/how-to/guide-to-pulsed-mig-welding-in-manufacturing).

## Delivered gas versus shielding at the arc

Correct cylinder contents do not guarantee adequate coverage. Miller identifies wrong gas-port connections, a poorly seated gun, nozzle spatter and excessive distance from the work as shielding problems. It suggests checking delivery with an external flowmeter at the gun when troubleshooting. A regulator indication upstream cannot by itself prove that gas reaches and protects the weld pool. [Miller, *What Type of Gas Is Best for MIG Welding in DIY Applications?*](https://www.millerwelds.com/en-us/resources/knowledge-hub/mig-welding/how-to/what-type-of-gas-is-best-for-mig-welding-in-diy-applications).

Set flow for the approved procedure, nozzle and transfer mode rather than adopting one value for all jobs. Hobart explains that insufficient, restricted or turbulent flow can produce porosity; wind can displace shielding, while excessive flow relative to nozzle diameter can entrain atmosphere. Check nozzle and diffuser obstruction, environmental drafts and delivery settings before increasing flow. Hobart also identifies oil, rust, moisture and other base-metal contamination as porosity sources, so a porous weld is not proof of incorrect gas composition. [Hobart Brothers, *MIG Troubleshooting for Metal-Cored and Solid Wire*, updated 10 July 2026](https://www.hobartbrothers.com/resources/technical-articles/mig-troubleshooting-for-metal-cored-and-solid-wire/).

For process setup, record the exact blend and grade, wire identification and diameter, material, transfer mode and machine program, nozzle configuration and validated flow. This is a practical selection checklist synthesized from the cited guidance. Keep composition changes visible when comparing trials; changing gas, waveform and wire together obscures the cause of a different result.

## Cylinder handling

Linde's Austrian SDS for 18% carbon dioxide/82% argon, version 1.7, classifies the mixture as compressed gas and warns of pressure hazards and asphyxiation at high concentrations. Its handling instructions require suitable pressure-rated equipment, leak checks, secured cylinders and appropriate cylinder carts; valves and relief devices must not be modified or repaired by the user. It requires well-ventilated storage and protection from heat. Follow the actual delivered product's regional SDS and container instructions. The linked document has conflicting revision dates between its first-page header and page footers, so it is identified here by version rather than assigning a single date. [Linde, *CO2 18%; Ar 82% Safety Data Sheet*, version 1.7, sections 2 and 7](https://produkte.linde-gas.at/sdb_konform/000010022086_EU_AT_EN_1.7.pdf).