Dayang Welding Materials Lecture Hall | MAG Welding Method
Today we introduce a welding method-MAG welding.
MAG welding is the English abbreviation for Fused Arc Active Arc Welding. MAG welding is a metal electrode gas shielded welding method that uses an active gas (such as CO2; Ar + CO2; Ar + CO2 + O2, etc.) as a shielding gas. It is called a molten electrode active gas shielded arc welding method, referred to as MAG welding.
The protective gas is made by adding a small amount of oxidizing gas (O2, CO2 or other mixed gas) to the inert gas. Because the protective gas is oxidizing, it is often used for welding of ferrous metals. 80% Ar + 20% CO2 mixed gas is commonly used in China. Because of the large proportion of argon in the mixed gas, it is often called argon-rich mixed gas shielded welding.
Combination of argon and oxidizing gas (small amount)
(1) Ar (argon) + O2 (oxygen)
The active gas containing O2 in Ar can be used for welding of stainless steel and other materials. Its biggest advantage is that it overcomes the problems of high viscosity of liquid metal and high surface tension when pure Ar protection welding stainless steel is used, and it is easy to produce pores. Poor wettability of the weld metal can easily cause undercuts. .
(2) Ar (argon) + CO2 (carbon dioxide)
This mixed gas is used to weld low carbon steel and low alloy steel. The commonly used mixing ratio (volume) is Ar 80% + CO2 20%. It has the advantages of stable Ar arc arc, small splash, easy to obtain axial spray transition, and oxidation. It overcomes the problems of large surface tension, viscous liquid metal, and easy drifting of cathode spots during argon welding. At the same time, it improves the welding depth of the mushroom shape.
(3) Ar (argon) + CO2 (carbon dioxide) + O2 (oxygen)
When using Ar 80% + CO2 15% + O2 5% mixed gas (volume ratio) to weld low-carbon steel and low-alloy steel, regardless of weld formation, joint quality, metal droplet transfer and arc stability, it is better than the above two. The mixed gas is better.
Use of oxidizing mixed gas as protection has the following advantages
(1) Improve the stability of the droplet transfer.
(2) Stabilize cathode spots and improve the stability of arc combustion.
(3) Improve the shape and appearance of weld penetration.
(4) Increase the thermal power of the arc.
(5) Control the metallurgical quality of welds and reduce welding defects.
(6) Reduce welding costs.
MAG welding can adopt short-circuit transition, spray transition and pulse spray transition for welding. It can obtain stable welding process and good welding joints. It can be used for welding in various positions, especially for ferrous metals such as carbon steel, alloy steel and stainless steel. Welding of materials.
MAG welding is mainly applicable to the welding of ferrous metals such as carbon steel, alloy steel and stainless steel, especially in the welding of stainless steel.