Welding is the process of joining metal parts with various fusible alloys (solder). The melting point of the solder is lower than that of the material to be soldered, so that the part will be welded by intermolecular contact on its surface without being melted.
Welding ensures the continuity of the metal. On the one hand, the two metals are connected to each other by bolting or physical attachment, which is expressed as a strong metal whole, but the connection is discontinuous, and sometimes the surface of the metal has an oxide insulating film, even Right or wrong physical contact. Another drawback compared to soldering is that the contact surface continues to oxidize and the resistance is added. In addition, chatter and other mechanical shocks can also loosen the joint. Welding eliminates these problems, the welding parts do not move relative to each other, the contact surfaces do not oxidize, and continuous conductive methods are adhered to. Welding is a process of fusion between two metals. In the molten state, the solder will dissolve some of the metal in contact with it, while the surface of the metal to be welded often has a thin layer of oxide film that cannot be dissolved by the solder. The flux is used to remove it. This layer of oxide film.