MIG welding feeds a wire electrode continuously through a gun while a shielding gas protects the weld pool. In Indian workshops it is often called CO2 welding, because carbon dioxide or an argon–CO2 mix is the usual gas for steel. It is fast and easy to learn, so it is the main process for mild steel fabrication: frames, structures, brackets, tanks and machine bases.
Quick facts
- Process
- Continuous wire electrode with shielding gas
- Gas
- CO2 or argon–CO2 for steel; pure argon for aluminium
- Wire
- ER70S-6 for mild steel, about 0.8–1.2 mm (0.0315–0.0472 inch)
- Thickness
- About 1 mm (0.0394 inch) upward; thick plate in several passes
- Speed
- Faster than TIG and stick
- Usually priced
- Per kg of weld, per metre or per part
MIG, TIG or stick?
| MIG (CO2) | TIG | Stick (arc) | |
|---|---|---|---|
| Speed | Fast | Slow | Medium |
| Look of the weld | Good, some spatter | Very neat | Slag to remove |
| Thin sheet | Good above about 1 mm (0.0394 inch) | Best | Hard |
| Outdoors, wind | Gas blows away | Gas blows away | Works well |
| Typical use | Mild steel fabrication | Stainless, aluminium, visible joints | Site work, repairs |
Quality checks
- Visual check for undercut, porosity and spatter
- Weld size measured with a fillet gauge
- Dye penetrant or ultrasonic testing for critical joints
- Welder qualification to the job's code where needed
What to send
- Drawing with weld symbols, sizes and lengths
- Material and thickness of each part
- Whether parts are supplied cut, or the workshop cuts and bends
- Finish after welding: grinding, painting, powder coating, galvanising
- Inspection or code needed, and quantity
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Questions
- Why is MIG called CO2 welding?
- Because CO2 gas is the cheapest and most common shielding gas for mild steel MIG welding in India.
- Can MIG weld stainless steel and aluminium?
- Yes, with the right wire and gas: argon-rich mixes for stainless and pure argon with a spool gun for aluminium.
- How do I reduce spatter?
- Use an argon–CO2 mix instead of pure CO2, the right voltage and wire speed, and clean material.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 29 October 2026.