Brazing refers to a welding method in which the solder below the melting point of the solder and the solder are heated to the melting temperature of the solder at the same time, and then the gap of the solid workpiece is filled with the liquid solder to connect the metal. When brazing, the oxide film and oil stains on the contact surface of the base metal must be removed first, so that the capillary will play a role after the solder is melted and increase the wettability and capillary fluidity of the solder. According to the melting point of the solder, brazing is divided into brazing and soft brazing.
The brazing deformation is small, and the joints are smooth and beautiful. It is suitable for welding precise, complex components and components composed of different materials, such as honeycomb structure plates, turbine blades, cemented carbide tools and printed circuit boards. Before brazing, the workpiece must be carefully processed and strictly cleaned to remove oil stains and excessively thick oxide film to ensure the interface assembly gap. The gap is generally required to be between 0.01 and 0.1 mm.
Compared with fusion welding, the base material does not melt during brazing, but only the solder melts; compared with pressure welding, no pressure is applied to the weldment during brazing. The weld formed by brazing is called brazing. The filler metal used in brazing is called brazing filler metal.
Brazing process: the cleaned surfaces of the workpieces are assembled together in a lap pattern, and the brazing material is placed near or between the joint gaps. When the workpiece and the solder are heated to a temperature slightly higher than the melting point of the solder, the solder melts (the workpiece is not melted) and is sucked into and fills the gap between the solid workpiece by capillary action. The liquid solder and the workpiece metal diffuse and dissolve each other. After condensation, a brazed joint is formed.
