1. When N2 is added into Ar, the temperature of arc is higher than that of pure argon. It is mainly used for welding copper and copper alloy. The disadvantage is that the welding spatter, and the weld surface is rough, the welding process is also accompanied by a certain amount of smoke.

2. Ar+O2 gas mixture has two types: one containing O2 content (volume fraction) is low, 1% ~ 5%, used for welding stainless steel; The other contains higher O2 content (volume fraction), can reach more than 20%, used for welding low carbon steel and low alloy structural steel.

The phenomenon of spot instability of arc cathode (cathode drift) can be overcome by adding 1% O2 in pure argon for welding stainless steel.

Cathode drift: The arc itself has the characteristics of jumping and adhesion. For black metals, because the oxide film on their surface is not as dense as magnesium and aluminum alloys, in the process of welding, the arc always looks for the oxide points on the microscopic surface of the metal to gather. Due to the jumping and adhesion of the arc, the arc is discontinuous, which will also produce arc deviation, that is, cathode drift. This leads to the instability of the arc. Adding some oxygen can oxidize the metal surface during welding to ensure the stability of welding arc.

3. Ar+CO2 is widely used in welding carbon steel and low alloy structural steel, can improve the impact toughness of weld metal and reduce spatter.

4. Ar+CO2+O2 three mixed can be used to weld low carbon steel, low alloy structural steel, weld forming, joint quality, drop transition and arc stability has a good effect.