Compared with conventional brazing, vacuum brazing mainly has the following characteristics:
vacuum brazing does not use flux, does not appear porosity, slag inclusion and other defects, can significantly improve the corrosion resistance of the product, not only can avoid environmental pollution, but also create conditions for safe production;
Vacuum brazing can save a lot of expensive metal flux, and does not need to use complex flux cleaning process, reducing production costs;
The wettability and fluidity of vacuum brazing filler metal are good, and it is easy to weld the workpiece with complex shape or narrow channel;
Suitable for brazing stainless steel, high-temperature alloys, especially heat-resistant alloys containing aluminum and titanium, which can obtain high-quality brazing joints, and also suitable for the connection of titanium, iron, niobium, molybdenum, tin and tantalum equivalent refractory alloys or dissimilar metals;
Because the weldment is heated under vacuum conditions, there will be no oxidation carburization, decarburization, pollution deterioration and other problems, the weldment is in the overall heating state in the furnace, so the thermal stress can control the deformation to the minimum limit; The matrix metal and filler metal are in a low pressure state around, which is easy to exclude the volatile impurities and gases released by the metal at the brazing temperature, which can improve the performance of the matrix metal itself; The heat treatment process of the welded part can be carried out together with the vacuum brazing process, and the brazing process can also be arranged as the final process.
The surface of the workpiece after vacuum brazing is not only clean and bright, but also easy to check the quality of the weld; The shortcomings of vacuum welding are that the one-time investment is large, the use of high consumption costs, maintenance is more complex, the requirements for the filler metal are more strict, and the assembly positioning requirements are higher, so that its application is subject to certain restrictions. It can braze multiple adjacent joints, and can braze multiple groups according to the capacity of the furnace, so it is a highly efficient welding method. Because vacuum brazing has many of the above advantages, its application field is very wide.
