The commonly used laser welding protection gases are mainly N2, Ar, He, whose physical and chemical properties are different, so the effect on the weld is also different.

1. Nitrogen N2

The ionization energy of N2 is moderate, higher than that of Ar and lower than that of He. The ionization degree of N2 is general under the action of laser, which can better reduce the formation of plasma cloud and thus increase the effective utilization rate of laser. Nitrogen can react with aluminum alloy and carbon steel at a certain temperature, producing nitride, which will improve the brittleness of the weld, and reduce toughness, which will have a great adverse effect on the mechanical properties of the weld joint, so it is not recommended to use nitrogen to protect aluminum alloy and carbon steel welds.

The nitrogen produced by the chemical reaction of nitrogen and stainless steel can improve the strength of the weld joint, which will be conducive to the improvement of the mechanical properties of the weld, so nitrogen can be used as a protective gas when welding stainless steel.

Nitrogen gas bottle

2. Argon Ar

Ar ionization energy relative to the minimum, under the effect of laser ionization degree is higher, is not conducive to control the formation of plasma cloud, can effective utilization of laser produce certain effect, but the Ar activity is very low, it is difficult to react with common metals, and Ar cost is not high, in addition, the density of Ar is bigger, is advantageous to the sink to the weld molten pool above, It can better protect the weld pool, so it can be used as a conventional protective gas.