CO2 gas protection electric arc welding is using CO2 as a protective gas electric arc welding method is melting. This method for CO2 gas as a protection medium, make arc and molten pool and air around isolation and prevent oxygen in air, nitrogen and hydrogen for investment and drop of molten pool metal harmful material, so as to achieve excellent mechanical protection performance. In the general is to use a specialized production of welding torch, form enough CO2 gas protection layer, rely on welding wire and welding arc between hot, automatic or semi-automatic melting extremely gas protect welding. This kind of welding method using automatic wire welding wire, apply the large amount of metal, high efficiency, stable quality. Therefore, in being widely applied both at home and abroad.

In the early 1930 s with CO2 and water vapor was put forward as a protection gas, but the result was the discovery weld metal heavy oxidation, stomatal many, not ensure welding quality. So the argon and helium inert gas shielded welding first used in the welding production, solve the aviation industry was in non-ferrous metal welding, the superiority of the gas shielded welding also gradually be people know and attention. But the argon, helium is a rare gas, the price is more expensive, the application of certain limits. Therefore, to the 1950 s. People to study and CO2 shielded welding, and gradually applied in welding production.

Argon and helium is inert gas with metal produces chemical reaction, also not soluble in metal, can play a good protection, and CO2 is a kind of gas oxidation. Especially in high temperature under the role of has strong oxidizing, but CO2 gas price is low, supply. Although it has a strong oxidation, but of the molten metal oxide can more easily deoxidizing; But on the other hand strong oxidation performance enough in welding seams of the existence of hydrogen inhibition, prevent to produce hydrogen porosity and crack; And CO2 good protection effect, still can effectively prevent the nitrogen in the air for investment droplets and pool of metal harm, it's very valuable, because the metal once nitriding, it is difficult to make denitrification.

CO2 welding wire of different diameter according to use, can be divided into filaments CO2 welding (welding wire than 1.6 mm in diameter) and thick welding wire CO2 welding (wires > 1.6 mm in diameter). According to the operation of the way classification, and can be divided into CO2 semi-automatic welding and automatic CO2 welding.