Metal Inert Gas Welding
Gas metal arc welding employing a continuously fed wire electrode under inert gas, primarily applied for non-ferrous metals and high-alloy steels.
MIG welding is an arc process with a consumable wire electrode. The shielding gas keeps air away from the weld pool, otherwise the metal burns and the weld becomes porous. If the gas flow is wrong or the gas runs out, you see it immediately on the weld – it turns black and crispy. Don't run at full speed, otherwise the material overheats and the structure becomes coarse and brittle. Conversely, too little current doesn't give proper penetration, then the weld won't hold. For steel use argon with CO2 content, for aluminum pure argon – and set the wire feed to match the voltage, then it runs stable.