What is brazing?

The energy source of brazing can be chemical reaction heat or indirect heat energy. It uses a metal with a melting point lower than that of the material to be welded as the solder. After heating, the solder melts, and the capillary action pushes the solder into the gap between the contact surfaces of the joint to wet the surface of the metal to be welded so that the liquid phase and the solid phase are separated. Interdiffusion between the phases to form a brazed joint. Therefore, brazing is a solid-phase and liquid-phase welding method.

1.The characteristics and application of brazing

Brazing uses an alloy with a melting point lower than that of the base metal as the solder. When heated, the solder melts and fills and remains in the joint gap by wetting and capillary action, while the base metal is in a solid state, relying on liquid solder and solid base Interdiffusion between materials forms a brazed joint. Brazing has little effect on the physical and chemical properties of the base metal, less welding stress and deformation, can weld dissimilar metals with large differences in properties, can complete multiple welds at the same time, the appearance of the joint is beautiful and tidy, the equipment is simple, and the production investment is small. However, the brazed joint has low strength and poor heat resistance.

Applications: Carbide cutting tools, drilling bits, bicycle frames, heat exchangers, conduits and various containers, etc.; in the manufacture of microwave waveguides, electron tubes and electronic vacuum devices, brazing is even the only possible connection method.

2. Solder and Flux

Brazing filler metal is the filler metal that forms the brazing joint, and the quality of the brazing joint depends largely on the brazing filler metal. The brazing filler metal should have a suitable melting point, good wettability and joint filling ability, can diffuse with the base metal, and should have certain mechanical properties and physical and chemical properties to meet the performance requirements of the joint. According to the different melting points of solder, brazing is divided into two categories: soft soldering and hard brazing.

Brazing can be used to weld metal materials such as carbon steel, stainless steel, superalloy, aluminum, copper, etc., and can also connect dissimilar metals, metals and non-metals. It is suitable for welding joints with little load or working at normal temperature, especially for precision, miniature and complex multi-braze weldments.