Dry Sharing of Gas Mixture Selection During Welding

In welding operations, selecting the appropriate gas mixture is the key to ensuring welding quality and efficiency. Here are some tips on selecting mixed gases to help you make more direct and accurate decisions.

The role of common welding gases

Ar: Commonly used in TIG welding and MIG welding because it can provide a stable arc and clean weld seam.

O ₂: Adding a small amount of O ₂ during certain welding processes can increase the temperature and fluidity of the molten pool.

CO ₂: When mixed with Ar, it is commonly used in MIG welding to improve welding speed and penetration depth.

He: Although the cost is high, it can increase the arc temperature and welding speed, especially suitable for welding materials such as aluminum alloys.

Mixed gases are mainly divided into two categories: binary mixtures and ternary mixtures.

Binary mixture gas

Binary gas mixture is a gas system composed of two gases mixed in a certain proportion. In welding, common binary mixtures include the following:

1. Ar+O ₂: Adding an appropriate amount of O ₂ to Ar can effectively improve arc stability and refine droplets. The combustion characteristics of O ₂ can increase the temperature of the metal in the molten pool, promote metal flow, reduce welding errors, make the weld bead smoother, accelerate welding speed, and improve welding efficiency. This mixed gas is suitable for welding carbon steel, low-alloy steel, and stainless steel of various thicknesses.

2. Ar+CO ₂: CO ₂ can improve welding strength and corrosion resistance, but pure CO ₂ protective gas splashes too much. Mixing stable Ar in it can effectively reduce the metal splashing rate. This mixed gas is also suitable for welding carbon steel and stainless steel.

3. Ar+H ₂: H ₂ is a reducing combustion gas that can increase arc temperature, accelerate welding speed, prevent bottom flow, reduce the formation of CO pores, and prevent welding defects. This mixed gas has good welding effects on nickel based alloys, nickel copper alloys, and stainless steel.

Ternary mixture

A ternary mixture is a gas system composed of three gases mixed in a certain proportion. In welding, common ternary mixtures include the following:

1. Ar+O ₂+CO ₂: This ternary mixture combines the advantages of Ar+O ₂ and Ar+CO ₂ binary mixtures, which can reduce welding spatter, improve melt flow, reduce bubble generation, and improve weld quality. It can be used for welding carbon steel, low-alloy steel, and stainless steel of different thicknesses, with a wide range of applications.

2. Ar+He+CO ₂: This mixed gas can improve arc stability and operability, as well as increase melt temperature, improve fluidity, and enhance welding quality and speed. Due to He being an inert gas with inactive chemical properties, its oxidation effect on the weld seam is minimal. This mixed gas is commonly used in various types of short-circuit arc welding and over welding.

Pay attention to the proportion of mixed gases during welding

The proportion of mixed gases directly affects the welding effect. For example, in a mixture of Ar and CO ₂ gas, an increase in the proportion of CO ₂ can improve welding speed and penetration depth, but may also increase the risk of splashing and porosity. Therefore, it is necessary to adjust the proportion of the mixed gas according to specific needs.

When selecting a mixed gas, factors such as the type and characteristics of welding materials, welding methods, and welding process requirements need to be considered. Different mixed gases have different characteristics and applicable ranges, and need to be selected according to specific situations.