Brazing/soldering is the process of joining metal objects using an additional molten metal, called solder, whose melting point is much lower than the melting point of the metals being joined. Therefore, during brazing/soldering, there is no melting of the materials to be joined, and the joint is achieved primarily by diffusion of the liquid solder into the metals to be joined and vice versa, and to a lesser extent by adhesion.
From the point of view of the type of solder used, brazing/soldering is divided into:
- soft brazing/soldering – components are joined using solders with a melting point below 500 ◦C, low hardness and high ductility,
- hard brazing/soldering – components are joined using solders with a melting point above 500 ◦C.
Brazing/soldering varieties also include:
- ultrasonic brazing/soldering – which uses the phenomenon of cavitation induced in the molten solder (which covers the surfaces of the parts to be soldered) and causes the breakdown and removal of the oxide layer so that the solder and the metal (aluminium or its alloys) are joined,
- non-fusion brazing/soldering – in which the joint is achieved solely by diffusion of the molten solder into the parent material, and the technique and preparation of the edges of the metals to be joined are analogous to those used in gas welding (the heat source is essentially an oxy-acetylene flame).
