*TIG welding (Tungsten Inert Gas welding) sounds quite high-tech, and indeed it is an oxygen-free welding method with relatively high requirements. In principle, it involves introducing argon, a gas with stable properties, to expel air and continuously cover the welding area. This prevents the metal in the welding zone from coming into contact with air, avoiding reactions between oxygen, nitrogen, and other gases in the air with the electric arc and the welding area, thereby achieving a high-quality welding effect.

The overall working principle is not complicated, but the requirements are quite high. First, the welding torch releases the inert gas argon to expel air from the spot to be welded, forming a gas-insulated area, which is equivalent to creating a vacuum-like state. Then, the power supply of the welding torch is turned on, and the electrode releases an electric arc after being energized with high voltage. Under the protection of high temperature and the "vacuum" (argon gas shield), the argon arc rapidly heats the welding wire and the base metal to extremely high temperatures, melting them. At the same time, welding materials are continuously added to meet the ongoing welding needs, thus completely welding the butt-jointed workpieces together. It should be noted that the voltage must be adjusted at any time according to the type of workpieces, the thickness of the plates, and the position of the welding spot to avoid piercing the welding spot or causing new damage due to excessively high intensity.

TIG welding uses a high-voltage breakdown method for arc striking. First, a high-frequency and high-voltage is applied between the electrode needle (tungsten needle) and the workpiece to break down the argon gas, making it conductive. Then, a continuous current is supplied to ensure the stable operation of the arc.

During welding, the arc is ignited by bringing the electrode (welding rod) into contact with the workpiece. Then, the electrode is lifted and kept at a certain distance. The arc burns stably under the appropriate arc voltage and welding current provided by the welding power supply, generating high temperatures that locally heat the electrode and the workpiece to a molten state. The molten metal at the end of the electrode and the molten metal of the workpiece fuse together to form a molten pool.

During the welding process, as the arc moves along with the electrode, the liquid metal in the molten pool gradually cools and crystallizes to form a weld seam, thus welding the two workpieces together.

The reason why argon arc welding can be widely applied is mainly due to the following advantages:

1.Argon gas protection can isolate the adverse effects of oxygen, nitrogen, hydrogen, etc. in the air on the arc and molten pool, reduce the burning loss of alloying elements, and thus obtain dense, spatter-free, and high-quality welded joints.

2.The arc of argon arc welding burns stably, with concentrated heat and high arc column temperature, resulting in high welding production efficiency, a narrow heat-affected zone, and low tendencies of stress, deformation, and cracking in the welded workpieces.

3.Argon arc welding is an open-arc welding process, making operation and observation convenient.

4.The electrode has little loss, the arc length is easy to maintain, and there is no flux or coating during welding, so it is easy to realize mechanization and automation.

5.Argon arc welding can weld almost all metals, especially some refractory metals and easily oxidizable metals, such as magnesium, titanium, molybdenum, zirconium, aluminum, and their alloys.

6.It is not restricted by the position of the workpiece and can perform all-position welding.

Characteristics:

High efficiency, high current density, concentrated heat, high deposition rate, and fast welding speed. In addition, it is easy to strike an arc. Strengthened protection is required because the arc light is strong and there is a lot of fume.