ELECTRON BEAM WELDING

In this process fusion is achieved by focusing a high power density beam of electrons on the area to be joined. Upon striking the metal, the kinetic energy of the high velocity electrons changes to thermal energy causing the metal to melt and the beam passes through the thickness of the plate thus making a keyhole. As the beam is moved, the keyhole also is moved leaving behind the molten metal to solidify. The electrons are emitted from a tungsten filament heated to approximately 3000 °C. The electron gun, the job and the fixtures are kept in a vacuum chamber. Very high welding speeds, high purity of welds and a very good control of weld parameters are possible to obtain by using this process. EB welding is highly suitable for welding of refractory metals such as tungsten, molybdenum, columbium tantalum and metals, which oxidise readily such as titanium, beryllium and zirconium. It can also be used to join aluminium, Steel and ceramics. EB machine is highly expensive but its use is justified for critical applications such as nuclear  and aerospace components fabrication.