Argon tungsten-arc welding
The tungsten electrode argon arc welding is often referred to as a TIG welding, and is an arc welding method for generating heat between the non-expendable electrode and the working object, This protection is supplied by a gas or mixed gas stream, which must be full protection because even a very small amount of air is mixed into the weld bead.
Principle
The tungsten electrode argon arc welding is a welding method for protection by using a tungsten rod as an electrode and argon, and the method is as shown in the figure. The argon gas is continuously sprayed from the nozzle of the welding gun at the time of welding, and the protective layer is formed around the arc to isolate the air so as to prevent the oxidation of the tungsten electrode, the molten pool and the adjacent heat-affected zone so as to obtain the high-quality welding seam. The welding wire can be added or not filled according to the specific requirements of the workpiece during the welding process.
Characteristic
Because the arc is burned in argon, it has the following advantages and disadvantages: 1) Argon has excellent protective effect and can effectively isolate the surrounding air; it itself does not react with metal or is insoluble in metal, which makes the metallurgical reaction in welding process simple and easy to control, so it provides good conditions for obtaining high quality weld. 2) the tungsten arc is very stable and can burn stably even at a very small current (< 10A), which is especially suitable for welding thin plate materials. 3) the heat source and the filled welding wire can be controlled separately, so the heat input can be adjusted easily, so this welding method can carry on the omni-directional welding, and it is also an ideal method to realize the one-sided welding and double-sided forming. 4) because the filled welding wire does not pass through the current, it does not produce splashing, and the weld is beautiful. 5) AC argon arc welding can automatically remove the oxide film on the surface of welding parts, so some non-ferrous metals with strong chemical activity, such as aluminum, magnesium and alloys, can be successfully welded. 6) the carrying current capacity of tungsten electrode is poor, excessive current will cause the melting and evaporation of tungsten electrode, and its particles may enter the molten pool and cause tungsten inclusion. Therefore, the deposition speed is small, the penetration depth is shallow, and the productivity is low. 7) Argon is more expensive, the deposition rate is low, and the argon arc welding machine is more complex, and other welding methods (such as electrode arc welding, submerged arc welding, CO2).
