Do you know what welding is?

Welding is the process of joining metal parts using various fusible alloys (solders). The melting point of solder is lower than that of the material to be welded, so that the component will end the welding through the contact between molecules on its surface without being melted.

Welding can be divided into soft soldering and hard soldering, the temperature of soft soldering is lower than 450°C, and the temperature of hard soldering is higher than 450°C. Hard soldering is usually used for silver, gold, steel, copper and other metals. Its solder joints are much stronger than soft soldering, and its shear strength is 20~30 times that of soft soldering. The term soldering is commonly used for both of the above thermal connections, since in both cases molten solder is written into the elongated gap between the two clean and close solid metal surfaces to be mounted.
Hand-held Welding Machine (MMA/Stick)

Welding ensures the continuity of the metal. On the one hand, the two metals are connected to each other by bolts or physical adhesion, which is a strong metal whole, but this connection is discontinuous. Sometimes, if there is an oxide insulating film on the surface of the metal, they even Right or wrong physical contact. Another disadvantage of mechanical connection compared with welding is that the contact surface continues to oxidize, resulting in an increase in resistance. Additionally, vibration and other mechanical shocks can loosen joints. Welding eliminates these problems, the welding part does not move relative to each other, the contact surface will not be oxidized, and the continuous conduction method can be maintained. Welding is a fusion process between two metals. In the molten state, solder will dissolve some metals that are in contact with it, and the surface of the metal to be welded often has a thin layer of oxide film that cannot be dissolved by solder. Flux is used to remove it. This layer of oxide film.
The welding process usually includes:

1) The melting of the flux, and then remove the oxide film on the surface of the metal to be welded;

2) Melting the solder to float the impure substances and lighter fluxes suspended in it to the surface;

3) Some of the metals connected with the solder are partially dissolved;

4) Cool and end the melting of metal and solder.