Laser Welding Protective Gases: How to Choose the Right Shielding Gas for Optimal Weld Quality

Protect the welding area

Prevent oxidation: During the laser welding process, the metal in the welding area is in a high-temperature state and is extremely prone to an oxidation reaction with the oxygen in the air. The protective gas can form a protective film in the welding area, isolating the air from the high-temperature metal and preventing the metal from oxidizing, thus ensuring the quality and performance of the weld seam. For example, when welding stainless steel, using argon gas protection can prevent the formation of scale on the weld seam.

4Fe+3O₂ → 2Fe₂O₃  

2Al+3O₂ →2Al₂O₃

Reduce porosity: The protective gas can expel the air around the welding area and reduce the dissolution of gases such as nitrogen and hydrogen in the air into the welding metal, thereby reducing the probability of the occurrence of defects such as porosity. This is because gases like nitrogen and hydrogen dissolve into the metal at high temperatures and form pores after cooling, affecting the compactness and strength of the weld seam. Nitrogen is extremely not recommended for welding materials including Ferrite.

3Fe+N₂ → Fe₃N₂

Improve the welding process

Stabilize the plasma: During laser welding, the high – energy – density laser beam causes the metal to evaporate and form plasma. The plasma scatters and absorbs the laser, reducing the energy transmission efficiency of the laser and affecting the welding quality and penetration. The protective gas can interact with the plasma to stabilize it, reducing its scattering and absorption of the laser, enabling the laser to act more effectively on the welding area, and improving the welding efficiency. For example, helium has a high ionization energy, which can effectively suppress the formation of plasma and stabilize the welding process. Helium’s heat higher transfer rate makes it easier to conduct the heat which will reduce the plasma in the seam surface surrounding.