As an efficient and accurate welding technology, laser welding is widely used in various industries. In the laser welding process, the protective gas plays a crucial role. It can not only prevent the oxidation of the weld, but also improve the quality of the weld and improve the welding efficiency.
This article will explore in depth the types, functions, selection and use of laser welding shielding gas to provide a comprehensive reference for the majority of laser welding engineers, equipment suppliers, researchers and enthusiasts.
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.
What is the Role of Laser Welding Shielding Gas
Prevent oxidation: Inert gas can form a protective layer to isolate active gases such as oxygen and nitrogen in the air, prevent weld oxidation, and ensure weld quality.
Stabilize the arc column: Shielding gas can stabilize the arc column, reduce the formation of plasma, and improve the utilization rate of laser energy.
Improve weld formation: Different shielding gases have different effects on weld formation. You can choose the appropriate shielding gas according to different welding requirements.
Cool weld: Some shielding gases have good thermal conductivity and can quickly cool the weld to reduce the heat affected zone.
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.
How to Choose Laser Welding Shielding Gas
Welding materials: Different welding materials have different requirements for shielding gas.
Welding process: Different welding processes have different requirements for the flow rate, purity, etc. of shielding gas.
Weld quality requirements: Select appropriate shielding gas according to the strength, toughness, appearance, etc. of the weld.
Cost: The cost of different shielding gases is different, and cost-effectiveness needs to be considered comprehensively.
How to Use Shielding Gas for Laser Welding
Gas purity: The purity of shielding gas directly affects the quality of welds, and generally requires a purity of more than 99.99%.
Gas flow: If the gas flow is too small, the weld cannot be effectively protected; if the gas flow is too large, gas is wasted.
Nozzle design: The design of the nozzle has an important influence on the distribution of shielding gas, and it is necessary to select a suitable nozzle according to different welding processes.
Gas preheating: In winter or in low temperature environments, the shielding gas needs to be preheated to prevent gas condensation.
Factors Affecting Welding Quality
- Type and purity of shielding gas
- Gas flow
- Nozzle design
- Welding speed
- Laser power
- Focus position
- Thickness and material of welding material
Conclusion
Laser welding shielding gas plays an important role in the laser welding process. Selecting the right shielding gas is the key to ensuring the quality of the weld. This article elaborates on the role, types, selection, and use of shielding gas, and gives corresponding optimization suggestions. I hope this article can provide valuable reference for readers.
