Application advantage of argon gas mixture
After a certain amount of another or two gases are included in one gas, satisfactory results can be obtained in such aspects as refining the droplet, reducing the splash, improving the stability of arc, improving the depth of fusion, improving the depth of fusion and improving the arc, respectively.
1. The advantages of Ar+He argon are very stable arc combustion and minimal splash. The advantages of helium gas are high arc temperature, large heat input of base metal and fast welding speed.
The advantages of argon gas can be obtained by adding a certain amount of helium gas.
When welding large thickness aluminum and aluminum alloy, Ar+He mixed gas can improve weld depth, reduce porosity and increase productivity. He with a volume fraction of 50% when the plate thickness is 10-20mm; When the plate thickness is greater than 20mm, 75% ~ 90% He is added.
When welding copper and copper alloy, Ar+He mixed gas can improve the wettability of welding seam and improve the quality of welding seam. The proportion of He is generally 50% ~75%(volume fraction).
2. The addition of Ar+H2 into argon can improve the arc temperature and increase the heat input of base metal. If TIG arc or plasma arc welding of stainless steel, in order to improve the welding speed, usually add volume fraction of 4% ~ 8%H2 in argon. < The reducibility of Ar+H2 mixed gas can be used to weld nickel and its alloys to suppress and eliminate CO pores in nickel welds. However, the added H2 content (volume fraction) must be less than 6%, otherwise hydrogen pores will be generated.
3. After adding N2 into Ar, the arc temperature of Ar is higher than that of pure argon. It is mainly used for welding copper and copper alloy. The disadvantages are spatter when welding, and the surface of the weld is rough, there is also a certain amount of smoke in the welding process.
4. There are two types of Ar+O2 mixed gas: one containing low O2 content (volume fraction), which is 1% ~ 5%, is used for welding stainless steel; The other has a higher O2 content (volume fraction), up to 20% or more, and is used for welding low carbon steel and low alloy structural steel.
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 spatter.
6. The mixture of Ar+CO2+O2 can be used to weld low carbon steel and low alloy structural steel, which has good effects on weld forming, joint quality, droop transition and arc stability.