Explain with sketch electron beam welding.
1 Answer
Answer :
Electron Beam Welding Process
In EBW process, the heat is generated when the electron beam impinges on work piece. As the high velocity electron beam strikes the surfaces to be welded, their kinetic energy changes to thermal energy and hence causes the work piece metal to melt and fuse. A schematic setup of the electron beam welding is shown in Fig.
This process employs an electron gun in which the cathode in form of hot filament of tungsten or tantalum is the source of a stream of electrons.
The electrons emitted from filament by thermionic emission are accelerated to a high velocity to the anode because of the large potential difference that exists between them.
The potential differences that are used are of the order of 30 kV to 175 kV. The higher the potential difference, higher would be the acceleration. The current levels are low ranging between 50 mA to 1000 mA. The electron beam is focused by a magnetic lens system on the work pieces to be welded.
The depth of penetration of the weld depends on the electron speed which in turn is dependent upon the accelerating voltage. When the high velocity electron beam strikes the work-piece all the kinetic energy is converted to heat. As these electrons penetrate the metal, the material that is directly in the path is melted which when solidifies form the joint.