Welding gas mixtures can be more than just a mixture of carbon dioxide and argon

1, The advantage of Ar+He argon is that the arc combustion is very stable and the splash is extremely small. The advantages of helium are high arc temperature, large base metal heat input, and fast welding speed.

With argon as the matrix, a certain amount of helium can be added to obtain the advantages of both.

When welding large thickness aluminum and aluminum alloys, the use of Ar+He gas mixture can improve the penetration depth of the weld, reduce porosity and increase productivity. When the plate thickness is 10~20mm, the volume fraction is 50% He; after the plate thickness is greater than 20mm, he with a volume fraction of 75% to 90% is added.

When welding copper and copper alloys, Ar+He gas mixture can improve the wettability of the weld and improve the quality of the weld. The proportion of He is generally 50% to 75% (volume fraction).

2, Ar+H2 in argon to add H2 can increase the arc temperature, increase the heat input of the base metal. For example, when welding stainless steel with TIG arc or plasma arc, in order to improve the welding speed, a volume fraction of 4% to 8% H2 is often added to argon.

Utilizing the reducibility of the Ar+H2 gas mixture, nickel and its alloys can be used to suppress and eliminate CO porosity in nickel welds. However, the added H2 content (volume fraction) must be less than 6%, otherwise it will lead to the production of hydrogen pores.

3, Ar +N2 After adding N2 in Ar, the temperature of the arc is higher than that of pure argon, mainly used for welding copper and copper alloys, this mixed gas is compared with Ar +He mixed gas, the advantage is that there are many sources of N2 and the price is cheap. The disadvantage is that there is a splash during welding, and the surface of the weld is rough, and there is also a certain amount of smoke during the welding process.

4, Ar + O2 gas mixture has two types: one contains low O2 (volume fraction), 1% to 5%, used for welding stainless steel; the other has a higher O2 content (volume fraction), up to more than 20%, used for welding low-carbon steel and low-alloy structural steel.

When adding O2 with a volume fraction of 1% to pure argon for welding stainless steel, it is possible to overcome the phenomenon of unstable arc cathode spots (cathode drift) when pure argon welds stainless steel.

Cathodic drift: the arc itself has jumping and adhesion, for ferrous metals, because the oxide film on their surface does not have the density of alloys such as magnesium and aluminum, in the process of welding, the arc always looks for oxide points on the microscopic surface of the metal to accumulate, due to the jumping and adhesion of the arc, resulting in arc discontinuity, which will also produce arc shift, that is, cathode drift, resulting in instability of the arc. Add a certain amount of oxygen, the metal surface will be oxidized during welding, ensuring the stability of the welding arc.

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

6. Ar+CO2+O2 hybrid can be used to weld low-carbon steel and low-alloy structural steel, which has a good effect on weld forming, joint quality, droplet transition and arc stability.

Turn to my gas network, if there is infringement, please inform, thank you.