In the welding process, the external impurities and moisture in the air will affect the welding seam, which will weaken the corrosion resistance of the welding seam, produce gas holes and reduce the durability of the welding seam. In order to protect metal melting droplets, molten pools and welding parts, and avoid metal being affected by external impurities and moisture in the air at high temperature, the welding area and the outside world will be isolated by protective gas in order to prevent adverse effects from the outside world.
Protective gases can be divided into two categories: inert gases and active gases. Inert gas refers to helium and argon, which do not react with the melt weld at all, and is used in MIG welding (metal-inert gas arc welding). Active gases generally include carbon dioxide, oxygen, nitrogen and hydrogen. These gases participate in the welding process by stabilizing the arc and ensuring that the material is smoothly transmitted to the weld. Most of them will destroy the weld, but a small amount of them can improve the welding characteristics for MAG welding (metal-active gas arc welding).
Therefore, in order to ensure the welding quality, the protective gas must be continuously released to form a protective barrier to protect the weld seam, and the protective sleeve must be kept free of blockage and gaps.