What Gases Are Needed For Laser Welding?

Laser welding is a high-precision welding method that uses a laser beam to melt the material of the workpiece and then forms a weld after cooling. In laser welding, gas plays a key role. The protective gas not only affects the welding seam formation, welding seam quality, welding seam penetration, and penetration width but also directly affects the quality and efficiency of laser welding. What gases are needed for laser welding? This article will take an in-depth look at the importance of laser welding gases, the gases used, and what they do.

Why is gas needed for laser welding?

During the laser welding process, a high-energy-density laser beam is focused on the welding area of the workpiece, causing instantaneous melting of the surface material of the workpiece. Gas is required during laser welding to protect the welding area, control the temperature, improve the quality of the weld, and protect the optical system. Choosing the appropriate gas type and supply parameters are important factors in ensuring an efficient and stable laser welding process and obtaining high-quality welding results.

Protection of welding areas

During the laser welding process, the weld area is exposed to the external environment and is easily affected by oxygen and other gases in the air. Oxygen triggers oxidation reactions that may lead to reduced weld quality, and the creation of pores and inclusions. The weld can be effectively protected from oxygen contamination by supplying an appropriate gas, usually an inert gas such as argon, to the welding area.

Heat Control

Gas selection and supply can help control the temperature of the welding area. By adjusting the flow rate and type of gas, the cooling rate of the welding area can be affected. This is important to control the heat-affected zone (HAZ) during welding and reduce thermal distortion.

Improved weld quality

Some auxiliary gases, such as oxygen or nitrogen, can improve the quality and performance of welds. For example, adding oxygen can improve the penetration of the weld and increase the welding speed, while also affecting the shape and depth of the weld.

Gas cooling

In laser welding, the welding area is usually affected by high temperatures. Using a gas cooling system can help control the temperature of the welding area and prevent overheating. This is essential to reduce thermal stress in the welding area and improve welding quality.

Gas protection of optical systems

The laser beam is focused on the welding area through an optical system. During the soldering process, the molten material and aerosols generated may contaminate optical components. By introducing gases into the welding area, the risk of contamination is reduced and the life of the optical system is extended.

Which gases are used in laser welding?

In laser welding, the gas can isolate the air from the welding plate and prevent it from reacting with the air. This way, the welding surface of the metal plate will be whiter and more beautiful. Using gas also protects the lenses from welding dust. Usually, the following gases are used:

Protective gas

Shielding gases, sometimes called “inert gases,” play an important role in the laser welding process. Laser welding processes often use inert gases to protect the weld pool. The commonly used protective gases in laser welding mainly include argon and neon. Their physical and chemical properties are different, so their effects on the weld are also different.

Argon: Argon is one of the most commonly used inert gases. It has a high degree of ionization under the action of the laser, which is not conducive to controlling the formation of plasma clouds, which will have a certain impact on the effective use of lasers. The inert nature of argon keeps it out of the soldering process, while it also dissipates heat well, helping to control the temperature in the soldering area.
Neon: Neon is often used as an inert gas, similar to argon, and is mainly used to protect the welding area from oxygen and other pollutants in the external environment. It is important to note that neon is not suitable for all laser welding applications. It is mainly used for some special welding tasks, such as welding thicker materials or when deeper weld seams are required.

Auxiliary gas

During the laser welding process, in addition to the main protective gas, auxiliary gases can also be used to improve welding performance and quality. The following are some common auxiliary gases used in laser welding:

Oxygen: Oxygen is commonly used as an assist gas and can be used to increase heat and weld depth during welding. Adding oxygen can increase welding speed and penetration, but needs to be carefully controlled to avoid excess oxygen causing oxidation problems.
Nitrogen: Nitrogen is also often used as an auxiliary gas in laser welding. The ionization energy of nitrogen is moderate, higher than argon and lower than hydrogen. The ionization degree is generally under the action of a laser. It can better reduce the formation of plasma clouds, provide higher quality welds and appearance, and reduce the impact of oxygen on the welds. Nitrogen can also be used to control the temperature of the welding area and reduce the formation of bubbles and pores.
Hydrogen/Hydrogen Mixture: Hydrogen improves the quality of welds and reduces the formation of porosity. Mixtures of argon and hydrogen are used in some special applications, such as welding stainless steel. The hydrogen content of the mixture typically ranges from 2% to 15%.
Helium: Helium is usually used for high-power laser welding because it has low thermal conductivity and is not easily ionized, allowing the laser to pass smoothly and the beam energy to reach the workpiece surface without any obstacles. Conducive to higher power welding. Helium can also be used to improve weld quality and control welding temperatures. This is the most effective shielding gas used in laser welding, but it is relatively expensive.

Cooling gas

Cooling gas is often used during laser welding to control the temperature of the welding area, prevent overheating, and maintain welding quality. The following are some commonly used cooling gases:

Water: Water is a common cooling medium often used to cool laser generators and laser welding optical systems. Water cooling systems can help maintain a stable temperature of the laser generator and optical components to ensure laser beam stability and performance.
Atmospheric gases: In some laser welding processes, ambient atmospheric gases can be used for cooling. For example, in the optical system of a laser generator, the surrounding atmosphere gas can provide a cooling effect.
Inert gases: Inert gases such as argon and nitrogen can also be used as cooling gases. They have lower thermal conductivity and can be used to control the temperature of the welding area and reduce the heat-affected zone (HAZ).
Liquid Nitrogen: Liquid nitrogen is an extremely low-temperature cooling medium that can be used for extremely high-power laser welding. It provides a very effective cooling effect and ensures temperature control in the welding area.

Gas selection in different applications

In different applications of laser welding, choosing the appropriate gas is crucial, because different gas combinations can produce different welding quality, speed, and efficiency. Here are some guidelines to help you choose the right gas for your specific application:

Type of welding material

Different materials require different gas combinations. Generally speaking:

Stainless steel typically uses argon or an argon/hydrogen mixture.
Aluminum and aluminum alloys often use pure argon.
Titanium alloys often use nitrogen.
High-carbon steels often use oxygen as an auxiliary gas.

Welding speed and penetration

If higher welding speed or deeper welding penetration is required, the gas combination can be adjusted. Adding oxygen often improves speed and penetration, but needs to be carefully controlled to avoid oxidation problems.

Weld quality

Some gas combinations can improve the quality and appearance of welds. For example, nitrogen can provide a better appearance and surface quality.

Pore and Bubble Control

For applications that require very high-quality welds, special attention needs to be paid to the formation of pores and bubbles. Proper gas selection can reduce the risk of these defects.

Control of Heat Affected Zone (HAZ)

Depending on the material being cleaned, hazardous waste that requires special handling procedures may be generated during the cleaning process. This can add to the overall cost of the laser cleaning process.

Equipment and cost considerations

Gas selection is also influenced by equipment type and cost. Some gases may require special supply systems or higher costs.

For specific applications, it is recommended to work with a welding engineer or a professional laser welding equipment manufacturer to obtain professional advice and optimize the welding process. Some experimentation and optimization are usually required before the final gas combination is selected. Depending on the specific application, different gas combinations and parameters can be tried to find the optimal welding conditions.

Summarize

In short, laser welding needs to use gas to protect welding areas, control temperature, improve weld quality, and protect optical systems. Selecting appropriate gas types and supply parameters is an important factor in ensuring an efficient and stable laser welding process and obtaining high-quality welding results. Different materials and applications may require different types and mixed proportions to meet specific welding requirements.
If you need to find a suitable customized laser welding machine, you can contact the account. We will provide you with a complete solution based on your budget and application, including appropriate machines, installation, and technical training. When you choose an AccTek Laser, you get more than just an excellent laser welding machine. You will also get the help of a special expert team, and they are committed to providing unparalleled customer support, training, and maintenance services.

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