Carbon dioxide gas shielded arc welding (referred to as CO2 welding) protects the gas from carbon dioxide (sometimes with co2+o2 mixed gas). Due to the special effects of 0 thermal and physical properties of carbon dioxide gas, when using conventional welding power, the molten metal at the end of the weld wire is not able to form a balanced axial free transition, and it is usually necessary to use short circuit and droplet necking, therefore, compared with the MIG welding, the splash is more. But if the use of high-quality welder, parameter selection is appropriate, you can get a very stable welding process, so that the splash to a minimum degree. Because of the low price of the protective gas, the weld is well formed when the short circuit is used, and the welding wire with the deoxidation agent can be used to obtain the high quality welded joint without internal defect. Therefore, this welding method has become one of the most important welding methods for black metal materials.