Answer: Argon arc welding: is short for tungsten inert gas shielded welding. In the welding process, the tungsten electrode does not melt, and the arc generated between the tungsten electrode and the weldment is used as the heating source to melt the weld metal. At the same time, argon gas is sent from the nozzle of the welding torch to protect the molten metal of the weld, and additional filler metal can be added as needed. Internationally known as: TIG welding.

Ordinary DC argon arc welding machine: It can weld almost all metals except aluminum and magnesium, because this welding method uses inert gas to protect the molten metal in the weld after heating by arc. Due to the protection of inert gas during welding, almost There are no other impurities and elements to participate in the welding process, and it is basically completed by the process of melting and condensing of the welded metal by itself, so a very high-quality weld can be obtained.

At the same time, because the stable welding current of DC tungsten arc welding can be adjusted very small, 3-5A can be stable welding, so it can weld very thin plates that cannot be welded by other common welding methods, including ordinary metals and their alloys.

AC argon arc welding machine: It is the best method for welding aluminum and magnesium among all the commonly used welding methods, because aluminum and magnesium are easily oxidized at room temperature. An oxide film with a melting point much higher than that of the metal itself will be formed on the metal surface (the melting point of aluminum is 657°C, and the melting point of alumina is 2050°C), so it is difficult to weld aluminum-magnesium and its alloys with high quality by ordinary welding methods. In the AC argon arc welding machine, when the current is in the negative half wave, the workpiece acts as an electrode and emits electrons, which will form a physical phenomenon called cathode crushing, which will break the refractory oxide layer on the surface of the workpiece. At the same time, due to the protection of inert gas, the new oxide layer will not be formed quickly; therefore, under the action of the arc heat, relying on the surface tension of the molten liquid metal itself, it is easy to fuse the weld metal together.

Because there is no need to add other chemicals and elements to remove the oxide film during AC argon arc welding, and only rely on the arc to remove the oxide film, the metal connection can be completed by the metal of the weldment under a pure welding arc, so that it will not be too much. Change the composition of the weld metal, resulting in excessive mechanical performance differences between the weld metal and the base metal. At the same time, there is no residual chemicals to corrode the weld metal, and it will not produce many welding defects like oxygen acetylene and electric welding. Therefore, argon arc welding is the best method for welding aluminum-magnesium and its alloys among all current welding methods. When choosing tungsten electrodes, in general DC welding, use cerium tungsten electrode as much as possible. For AC argon arc welding, because the rectification effect of pure tungsten is small, it is more effective to eliminate the DC component of the welding process, and it is easier to start the arc and maintain the arc. When welding aluminum workpieces, use pure tungsten electrodes as much as possible; however, because pure tungsten electrodes are not as high-temperature resistant as cerium tungsten electrodes, and when AC argon arc welding, the tungsten electrode heats up higher than DC welding, so the diameter of the tungsten electrode is slightly required. Big.

Disadvantages of argon arc welding: 1) shallow penetration and low production efficiency. 2) The inert gas is more expensive and the production cost is high.

Term explanation: W—non-melting extremely inert gas shielded welding machine S—manual welding M—pulse E—AC/DC