Gas shielded welding is a welding method that uses external gas to protect the arc and molten pool, achieving the connection of metal materials. Gas shielded welding has become one of the most commonly used welding methods in modern industry due to its advantages of good welding quality, high efficiency, and easy automation.

This article will introduce several common welding methods of gas shielded welding, including carbon dioxide gas shielded welding, melt inert gas shielded welding, non melt inert gas shielded welding, etc., as well as their characteristics, applicability, and precautions.

I. Carbon dioxide gas shielded welding

Carbon dioxide gas shielded welding (CO2 welding) is a welding method that uses pure carbon dioxide gas as the shielding gas and molten metal electrodes as the arc medium and filler metal. CO2 welding has the following characteristics:

The welding current density is high, the arc is stable, and the melting depth is large, making it suitable for welding thick plates.

Fast welding speed, high efficiency, low cost, suitable for mass production.

The weld seam is well formed, with a flat surface and high mechanical properties, suitable for welding with high quality requirements.

During the welding process, there is a significant amount of splashing and smoke, and effective protective measures need to be taken.

During the welding process, carbon dioxide will decompose into carbon monoxide and oxygen, which have a certain active effect on the molten pool, which may lead to a decrease in carbon content or an increase in oxygen content in the molten pool, affecting the mechanical properties and corrosion resistance of the weld.

Scope of application of CO2 welding: CO2 welding is suitable for the welding of black metals such as low-carbon steel, low alloy steel, stainless steel, etc. It can also be used for surfacing or repair welding of non-ferrous metals such as cast iron and aluminum alloy. CO2 welding usually adopts a direct current positive electrode connection method, which means that the workpiece is connected to the negative electrode and the electrode is connected to the positive electrode. This can concentrate the arc energy on the workpiece, increase the melting depth, and reduce splashing. CO2 welding can also use pulse power or low-frequency pulse power to improve arc stability and transition mode.

II Metal inert gas shielded welding

MIG/MAG is a welding method that uses inert gas or a mixture of gases as the shielding gas and molten metal electrodes as the arc medium and filler metal. MIG/MAG welding has the following characteristics:

Welding current density is low, arc is gentle, and fusion depth is small, suitable for thin plate or position welding.

Welding speed is slow, efficiency is low, and cost is high, making it suitable for small batch or precision production.

The weld formation is poor, and the surface is prone to defects such as dents, cracks, and holes, which require post-treatment or repair.

During the welding process, there is less spatter and smoke generated, resulting in lower protection requirements.

During the welding process, the protective gas has no active effect on the molten pool and will not affect the chemical composition of the molten pool, ensuring the mechanical and corrosion resistance of the weld seam.

Application scope of MIG/MAG welding: MIG/MAG welding is suitable for the welding of non-ferrous metals and their alloys such as aluminum, magnesium, copper, titanium, etc. It can also be used for the welding of ferrous metals such as stainless steel and high-strength steel. MIG/MAG welding usually adopts a DC positive electrode connection method, which means that the workpiece is connected to the negative electrode and the electrode is connected to the positive electrode. This can concentrate the arc energy on the electrode, increase the melting speed of the electrode, and reduce the melting depth. MIG/MAG welding can also use AC power or high-frequency pulse power to improve arc stability and transition mode.

III. Non consumable inert gas shielded welding

Non melting inert gas shielded welding (TIG) is a welding method that uses inert gas as the shielding gas, non melting tungsten electrode as the arc medium, and adds or does not add filler metal. TIG welding has the following characteristics:

The welding current density is small, the arc temperature is high, and the penetration depth is large, making it suitable for thick plate or deep penetration welding.

Welding speed is fast, efficiency is high, and cost is low, making it suitable for large-scale or high-efficiency production.

The weld seam is well formed, with a smooth surface and high mechanical properties, suitable for welding with high quality requirements.

During the welding process, there is less spatter and smoke generated, resulting in lower protection requirements.

During the welding process, the protective gas has no active effect on the molten pool and will not affect the chemical composition of the molten pool, ensuring the mechanical and corrosion resistance of the weld seam.

Application scope of TIG welding: TIG welding is suitable for the welding of difficult to weld metals and their alloys such as aluminum, magnesium, titanium, zirconium, etc. It can also be used for the welding of black metals such as stainless steel and alloy steel. TIG welding usually adopts a DC reverse electrode connection method, which connects the workpiece to the positive electrode and the electrode to the negative electrode. This can concentrate the arc energy on the workpiece, increase the melting depth, and reduce electrode loss. TIG welding can also use AC power or high-frequency pulse power to improve arc stability and transition mode.