Ultrasonic gas measurement technology realizes the measurement of mixed gas, long life, high precision, and maintenance-free, which ensures the stability of the mixed gas concentration.
Measurement and application of mixed gas, tests have confirmed that after adding a certain amount of another gas or two gases to one gas, it can be used to refine the droplets, reduce splashes, improve the stability of the arc, improve the penetration depth and Satisfactory results were obtained in terms of arc temperature.
There are several commonly used mixed gases:
- The advantages of Ar + He argon are that the arc combustion is very stable and the splash is very small. The advantages of helium gas are high arc temperature, large heat input of base metal, and fast welding speed.
With argon as the matrix, adding a certain amount of helium can get the advantages of both.
When welding large thickness aluminum and aluminum alloy, using Ar + He mixed gas can improve weld penetration, reduce porosity and increase productivity. When the thickness of the plate is 10-20mm, the volume fraction of He is 50%; when the thickness of the plate is greater than 20mm, the volume fraction of He is added 75% -90%.
When welding copper and copper alloys, the Ar + He mixed gas can improve the wettability of the weld and the quality of the weld. The proportion of He is generally 50% to 75% (volume fraction).
- Ar + H2 Adding H2 in argon can increase the arc temperature and increase the heat input of the base metal. For example, when welding stainless steel by TIG arc or plasma arc, in order to increase the welding speed, 4% to 8% H2 is often added in argon.
Utilizing the reducibility of Ar + H2 mixed gas, it 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.
- Ar + N2 After adding N2 to Ar, the temperature of the arc is higher than pure argon. It is mainly used for welding copper and copper alloys. Compared with Ar + He mixed gas, this mixed gas has the advantages of more N2 sources and cheaper prices . The disadvantage is that there are spatters during welding, and the surface of the weld is rough, and there is a certain amount of smoke during the welding process.
- There are two types of Ar + O2 mixed gas: one with low O2 content (volume fraction), which is 1% to 5%, used for welding stainless steel; the other with high O2 content (volume fraction), can be More than 20%, used for welding low carbon steel and low alloy structural steel.
When adding O2 with a volume fraction of 1% in pure argon to weld stainless steel, the phenomenon of arc cathode spot instabilit.com. y (cathode drift) can be overcome when welding pure stainless steel with pure argon.
- Ar + CO2 is widely used in welding carbon steel and low alloy structural steel, which can improve the impact toughness of the weld metal and reduce spatter.
- The mixture of Ar + CO2 + O2 can be used to weld low carbon steel and low alloy structural steel, which hasgood effects on weld formation, joint quality, droplet transfer and arc stability.
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