Diffusion welding
The method is based on the diffusion of metals. The coupled parts are placed in the welding chamber that is filled with an inert or reducing gas (in our industry is rarely used), while maintaining a constant vacuum of the order of (10 2 - 10 5 ) mm Hg. of Art. Details of the chamber is heated and compress specific pressure of the order of 0.5-2 kg / mm 2 . The vacuum is maintained continuously, the work of vacuum pumps, bilge gases coming into the welding chamber through leaks of the system, as well as adsorbed surfaces of equipment and allocated continuously heated metal from the surface and from the volume. Very important is the temperature of heating the metal, steel is usually heated to 800 ° C. There is a purification of the metal surface, remove surface contamination and adsorbed gases are reduced and dissolved in the metal oxides. Welding surface should be well-machined to ensure the entire surface of contact welding. Continuously active pressure crushes all projections and irregularities of hot metal and provides the necessary adhesion to the surface.
The processes of cleaning, fitting surfaces and diffusion are quite slow and it takes 5-20 minutes, and sometimes more to complete the welding process. Heating of the parts are usually electric, and in different cases, the radiation of heaters, and sometimes the heat transfer from the heater through the heat conductivity and the possible induction heating.
The heating temperature and its control are of great importance, it is a small increase dramatically accelerates the diffusion on the other hand, the heating can reduce the quality of the metal. The method is distinguished by high flexibility with respect to weld metals can be welded many combinations of dissimilar metals, and metals with metal alloys, metal ceramics, and graphite, etc. The method was already widely used for different occasions, often are difficult in other ways.
See also:
Blacksmith (Forge) Welding
Blacksmith (Forge) Welding Part 2
Induction (high frequency) Welding
Diffusion Welding
Casting or Foundry Welding
Friction Welding
Electrolytic Welding
Welding Under Water
Explosive Welding
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