What shielding gas should I use for laser welding machine?

In laser welding, shielding gas will affect the weld formation, the weld quality, the weld depth, and the weld width, etc.In most cases, the blowing of the shielding gas will have a beneficial effect on the weld, but bad use may also bring adverse effects.

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The positive effect of shielding gas on laser welding

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●Proper blowing of the shielding gas will effectively protect the weld pool from oxidation and even avoid oxidation;

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●Laser welder,Proper blowing of the shielding gas can effectively reduce the splash generated during the welding process and protect the focusing mirror;

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Proper blowing of the shielding gas can promote the uniform spreading of the weld pool during solidification so that the weld more  formed and beautiful;.

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●Laser welding machine,proper blowing of the shielding gas can effectively reduce metal vapor or the shielding effect of the plasma cloud on the laser so that the laser energy reaching the surface of the workpiece, and thereby increase the effective utilization rate of the laser;

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●Proper blowing of the shielding gas can effectively reduce weld porosity.

Choose right gas type, gas flow rate, and blowing , it can achieve good result.However, improper use of shielding gas can also have adverse effects on welding.

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Adverse effects of improper use of shielding gas on laser welding

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●Improper blowing of shielding gas may cause the weld to deteriorate;

●Choosing the wrong type of gas may cause cracks in the weld, and may also lead to the reduction of weld mechanical properties;

●Choosing the wrong type of gas may cause the weld to be more oxidized (whether the flow is too large or too small), or it may cause the weld pool metal to be seriously disturbed by the external force to cause the weld to collapse or form unevenly;

●Choose the wrong gas blowing method will result in the weld not achieving the protective effect or negatively affecting the weld formation;

●Insufflation of the shielding gas will have a certain effect on the weld penetration, especially when the thin plate is welded, the weld penetration will be reduced.The commonly used laser welding shielding gas is mainly N2(nitrogen), Ar(argon), He(helium), and their physicochemical properties are different, so the effect on the weld is different.

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●Nitrogen N2—can be used for welding shielding gas of stainless steel

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The ionization energy of N2 is moderate, higher than that of Ar, lower than that of He, and the ionization degree under the action of laser is general, which can better reduce the formation of plasma cloud, thereby increasing the effective utilization of laser.Nitrogen can react with aluminum alloy and carbon steel at a certain temperature to produce nitrides, which will improve the brittleness of welds and reduce the toughness, and have a great adverse effect on the mechanical properties of the weld joint.Therefore, it is not recommended to use nitrogen to protect the weld of aluminum alloy and carbon steel.The nitride produced by the chemical reaction between nitrogen and stainless steel can improve the strength of the welded joint and improve the mechanical properties of the weld. Therefore, nitrogen can be used as a shielding gas when welding stainless steel.

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●Argon Ar— high-cost performance, the most conventional shielding gas

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The ionization energy of Ar is relatively low, and the degree of ionization is high under the action of the laser, which is not conducive to controlling the formation of the plasma cloud, and will have a certain influence on the effective utilization of laser.However, the activity of Ar is very low, and it is difficult to react with common metals, and the cost of Ar is not high.Besides, the density of Ar is large, which is conducive to sinking above the weld pool and can better protect the weld pool. Therefore, Ar can be used as a conventional shielding gas.

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●Helium He—the best but also the most expensive shielding gas

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He has the highest ionization energy and low ionization under the action of laser.

It can control the formation of the plasma cloud very well, and the laser can work well on metal.

Moreover, the activity of He is very low, and it does not chemically react with metals, so it is a good weld shielding gas.However, the cost of He is too high to be suitable for mass production products.

Most of time it use for scientific research or products with very high added value.so 

Hope this information is helpful for you.If you have any questions of machine,please contact to us.

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