Types of shielding gases for laser welding machines
The commonly used shielding gases for laser welding are mainly N2, Ar, and He, and their physical and chemical properties are different, so their effects on the weld are also different.
1. Nitrogen N2
The ionization energy of N2 is moderate, higher than that of Ar, and lower than that of He. Under the action of laser, the ionization degree is average, which can better reduce the formation of plasma cloud, thereby increasing the effective utilization of laser. Nitrogen can chemically react with aluminum alloy and carbon steel at a certain temperature to generate nitrides, which will increase the brittleness of the weld and reduce the toughness, which will 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 nitrides produced by the chemical reaction between nitrogen and stainless steel can improve the strength of the weld joint, which will help improve the mechanical properties of the weld, so nitrogen can be used as a protective gas when welding stainless steel.
The ionization energy of Ar is relatively low, and the degree of ionization under the action of the laser is relatively high, which is not conducive to controlling the formation of plasma clouds, and will have a certain impact on the effective utilization of the laser. However, the activity of Ar is very low, and it is difficult to chemically react with common metals. reaction, and the cost of Ar is not high. In addition, the density of Ar is large, which is conducive to sinking to the top of the weld pool, which can better protect the weld pool, so it can be used as a conventional shielding gas.
3. Helium He
The ionization energy of He is the highest, and the ionization degree is very low under the action of the laser, which can well control the formation of the plasma cloud. It is a good weld shielding gas, but the cost of He is too high. Generally, this gas is not used in mass-produced products. He is generally used for scientific research or products with very high added value.
The selection of shielding gas directly affects the quality, efficiency and cost of welding production. However, due to the diversity of welding materials, the selection of welding gas is also relatively complicated in the actual welding process. It is necessary to comprehensively consider welding materials, welding methods, and welding positions. As well as the required welding effect, only through the welding test can a more suitable welding gas be selected to achieve better welding results.