What is the difference between brazing and pressure welding

First, brazing is to use the metal material with lower melting point than the base metal as the brazing filler metal, to heat the weldment and the brazing filler metal to a temperature higher than the melting point of the brazing filler metal and lower than the melting temperature of the base metal, use the liquid brazing filler metal to wet the base metal, fill the joint gap and realize the connection of the weldment by mutual diffusion with the base metal. With small brazing deformation and smooth and beautiful joints, it is suitable for welding precise, complex and components composed of different materials, such as honeycomb structure plate, turbine blade, cemented carbide cutter and printed circuit board. Before brazing, the workpiece must be processed carefully and cleaned strictly to remove the oil stain and the too thick oxide film, so as to ensure the assembly clearance of the interface. The clearance is generally between 0.01 and 0.1mm.

As one of the three welding processes, brazing is different from fusion welding and pressure welding. Fusion welding uses external heating (such as electric arc) to heat and melt the local area of the interface of the connected component (i The material is melted.

Second, pressure welding, commonly known as solid-state welding, is a welding process that under the action of pressure (or heating at the same time), plastic deformation occurs on the separated metal joint surface to make the metal connection become a whole. There are two forms of this kind of welding, which can be pressed after heating or directly cold pressed, and the compression joint is relatively firm.

Heating and pressing: heat the contact part of the welded metal to the plastic state or local melting state, and then apply certain pressure to make the metal atoms combine with each other to form a solid welding joint. For example, forging welding, contact welding, friction welding, gas pressure welding, resistance welding, ultrasonic welding and so on are the pressure welding methods of this type.