Gas welding (GMAV), by definition, is an arc welding process that produces metal coalescence by heating an arc between the auxiliary metal electrode and the part. The process uses gas protection from the outside to protect the molten weld pool. Application GMAV generally requires DC + (reverse) polarity of the electrode.
In non-standard terminology, GMAV is commonly known as MIG (under inert gas) welding, and less commonly known as MAG (under active gas) welding. In both cases, the GMAV process is suitable for welding a wide range of solid carbon steel and tubular electrodes with a metal core. The range of alloyed materials for GMAV includes: carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze and tubular alloys for surface treatment with a metal core. The GMAV process is suitable for semi-automatic, robotic automation and hard automated welding applications. 
Advantages of GMAV
The GMAV process enjoys wide application due to its ability to provide high quality welded joints, for a wide range of alloys of iron and non-ferrous iron, at a low cost. GMAV also has the following benefits:
• Ability to combine a wide range of types and thicknesses of materials.
• Simple equipment components are easily accessible and affordable.
• GMAV has higher electrode efficiency, usually between 93% and 98%, compared to other welding processes.
• Higher welder efficiency and operator factor, compared to other open arc welding processes.
• GMAV easily adapts to high robot speeds, heavy automation and semi-automatic welding applications.
• Possibility of welding in all positions.
• Great seam appearance.
• Lower layer of hydrogen in the weld – generally less than 5 mL / 100 g of weld metal.
• Lower heat input compared to other welding processes.
• Minimal splashes and slag make cleaning welds quick and easy.
• Less welding fumes compared to SMAV (protected arc metal welding) and FCAV (core arc welding) processes.
• Generally, lower cost per length of weld metal applied when compared to other open arc welding processes.
• Lower electrode cost.
• Minor distortions with GMAV-P (impulse spray transfer mode), GMAV-S (short circuit transfer mode) and STT (surface Tension Transfer ™).
• Resolves bad fit with GMAV-S and STT modes.
• Reduced welding fumes.
• Minimal cleaning after welding.
Limitations of GMAV
• Lower thermal input, short-circuit characteristic, metal transfer mode limits its use to thin materials.
• Higher heat input and axial spray transfer generally limit its use for material thicknesses.
• The higher heat input mode of the axial spray is limited to straight or horizontal welding positions.
• The use of shielding gas based on argon for axial spraying and pulse spray transfer regimes are expensive than 100% carbon dioxide (CO2).