What is the Soldering and Brazing
Brazing, refers to the solder below the melting point of the weldment and weldment at the same time heated to the melting temperature of the brazing filler, the use of liquid solder to fill the gap of the solid workpiece so that the metal connection welding method. Brazing, the first to remove the base metal oxide film contact surface and oil, in order to facilitate the capillary tube after the solder melts play a role in increasing the solder wettability and capillary flow. According to the different solder melting point, brazing is divided into brazing and soldering.
Brazing deformation is small, the joints smooth and beautiful, suitable for welding precision, complex and made of different materials, such as honeycomb structural plates, turbine blades, carbide cutting tools and printed circuit boards. Brazing before the workpiece must be meticulous processing and strict cleaning, remove the oil and over thick oxide film to ensure that the interface assembly clearance. Gap is generally required between 0.01 ~ 0.1 mm.
Compared with the welding, welding the base metal is not melted, only the solder melts;
Compared with pressure welding, brazing does not exert pressure on the weldment.
The weld formed by brazing is called a brazing seam.
The filler metal used in brazing is called solder.
Brazing process: the surface of the workpiece is cleaned to lap the assembly together, the solder placed in the joints near the gap or joint gap between. When the workpiece and the brazing filler metal are heated slightly above the melting temperature of the brazing filler metal, the brazing filler metal melts (the workpiece is not melted), and is imbibed and filled with the capillary action between the solid workpiece gaps. The liquid brazing filler metal and the workpiece metal interdiffuse and dissolve, Condensation after the formation of brazed joints.
⑴ brazing heating temperature is low, the joint smooth and flat, small changes in mechanical and mechanical properties of small deformation, the workpiece size is accurate.
⑵ welding dissimilar metals, but also welding dissimilar materials, and the thickness of the workpiece without strict restrictions.
⑶ some brazing methods can weld more welding parts, more joints, high productivity.
⑷ brazing equipment is simple, less investment in production costs.
⑸ connector strength is low, heat resistance is poor, and the strict requirements before welding cleaning, solder prices more expensive
First, the joint surface smooth, good air tightness, shape and size stability, weldment and performance changes little organization, can be connected to the same or different metals and some non-metallic. Brazing, the workpiece can also be used to heat the whole, a lot of welding a lot of welding, improve productivity. However, the lower strength of brazed joints, and more use of lap joints, by increasing the lap length to improve the strength of the joint; In addition, the preparation of the pre-brazing work requires a higher.
Second, the solder is melted and the weldment is not melted. In order to make the brazing part firmly connected to enhance the adhesion of the brazing filler metal, brazing flux, in order to remove the brazing filler metal and the surface of the oxide. Brass (such as copper-based, silver-based, aluminum-based, nickel-based, etc.), with high strength, can be connected to bear the load parts, widely used, such as carbide cutting tools, bicycle frame. Solder (such as tin, lead, bismuth, etc.), the welding strength is low, mainly for welding does not bear the load but requires a good seal of weldment, such as containers, instrumentation components.
The brazing uses an alloy with a melting point lower than that of the base metal as a brazing filler metal. When heating, the brazing filler metal melts and fills and retains in the joint clearance by wetting and capillary action while the base metal is in a solid state. Mutual diffusion between the material to form a brazed joint. The physical and chemical properties of the parent metal has little effect on the parent metal, welding stress and deformation is small, the weldability of dissimilar metals with large differences in the ability to complete multiple weld at the same time, the appearance of the joints beautiful and tidy, simple equipment, small investment in production. However, the lower the strength of brazed joints, poor heat resistance.
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