Many friends did not understand the shielding gas of laser welding machines when they bought the laser welding machine. In fact, the physical and chemical properties of laser welding are different. The shielding gas mainly includes N2, Ar, He. The effect on the weld is also different.
What is shielding gas used for in welding
The use of shielding gas during laser welding is to protect the focusing lens, prevent the oxidation of the base material, and improve the quality of welding.
3 Kinds of Laser Welding Shielding Gas
- Nitrogen N2
- Argon Ar
- Helium He
Nitrogen N2
Can be used for laser welding shielding gas for stainless steel
The ionization energy of N2 is moderate, higher than that of Ar and lower than that of He. Under the action of the laser, the ionization degree is average, which can reduce the formation of a plasma cloud and increase the effective utilization rate of the laser.
Nitrogen can chemically react with aluminum alloy and carbon steel at a certain temperature to produce nitrides, which will increase the brittleness of the weld, reduce the toughness, and have a greater adverse effect on the mechanical properties of the weld joint. Therefore, it is not recommended to use nitrogen. Aluminum alloy and carbon steel welds are protected.
The nitride produced by the chemical reaction between nitrogen and stainless steel can increase the strength of the weld joint, which will help improve the mechanical properties of the weld. Therefore, nitrogen can be used as a shielding gas when welding stainless steel.
Argon Ar
Cost-effective, the most conventional protective gas.
The ionization energy of Ar is relatively low, and the ionization degree is high under the action of laser, which is not conducive to controlling the formation of plasma cloud, and will have a certain impact on the effective utilization of laser. However, the activity of Ar is very low and it is difficult to chemically interact with common metals The cost of Ar is not high. In addition, the density of Ar is higher, which is beneficial to sink to the top of the weld pool, and can better protect the weld pool, so it can be used as a conventional shielding gas.
Helium He
The best but also the most expensive protective gas.
He has the highest ionization energy, and the ionization degree is very low under the action of laser, which can well control the formation of plasma cloud. Laser can act on metal very well, and He has very low activity and basically does not chemically react with metal. It is a good shielding gas for welding seams, but the cost of He is too high.
Generally, mass production products will not use this gas. He is generally used for scientific research or products with very high added value.