Electron beam welding uses thermal emission or field emission cathode to generate electrons,  and accelerates to a high speed under the action of a high voltage electric field between the  cathode and the anode. After focusing by a primary or secondary magnetic lens, a dense  high-speed electron flow is formed.  when the high-speed electron flow hits the surface of the workpiece, the high-speed moving electrons interact with the internal atoms or molecules of the workpiece. Heating, melting and vaporization, so as to achieve the purpose of welding.

Due to its unique heat transfer mechanism and pure welding environment, vacuum electron beam welding has the following advantages compared with other fusion welding methods:

1.The penetration ability of the electron beam is strong, and the depth-to-width ratio of the weld is large, which can reach 50:1 internationally, and 15-25:1 on domestic production equipment.

2. Electron beam welding can achieve single-pass large-thickness welding without opening grooves. The one-time single-pass welding depth of foreign research institutions can reach 300 mm, and domestic production equipment can reach 70-100 mm, which can save auxiliary materials compared with arc welding. The consumption of materials and energy is dozens of times, and the welding efficiency is high.

3. Fast welding speed and small heat-affected zone. The welding speed of electron beam welding is generally above 0.5-1m/min, and the heat-affected zone of electron beam welding seam is very small, sometimes almost non-existent.

4. Small welding deformation. The minimum welding line energy of electron beam welding and the characteristics of "parallel weld seam" make the deformation of electron beam welding less. Therefore, for finished workpieces, electron beam welding can be used as the final connection process, and the high precision of foot movement can still be maintained after welding.

5. Welding in a vacuum environment is conducive to improving the quality of the weld. Vacuum electron beam welding can not only prevent the molten metal from being polluted by hydrogen, oxygen, nitrogen and other harmful gases, but also facilitate the degassing and purification of the weld metal, so it is especially suitable for the welding of active metals. Electron beam welding is also commonly used to weld vacuum-sealed components, and the interior of the components remains in a vacuum state after welding.

6. Good welding accessibility. The electron beam can be transmitted to a far position for welding in a vacuum, as long as the beam current can reach, it can be welded. Therefore, it is possible to carry out welding of difficult-to-access parts such as welding torches and electrodes by general welding methods.

7. The electron beam is easy to control. Welding of complex seams can be achieved by controlling the deflection of the electron beam. Defects can be eliminated by scanning the melt pool with an electron beam, improving joint quality.