Electronbeam WeldingElectron Beam is a power beam process that uses a stream of electrons brought to a focus to provide an intense heat source. Electrons are emitted at very high voltages, up to 200kV, accelerated through an anode and focussed by an electromagnetic lens. Electron beam welders work at about 100kW power. The whole process is normally carried out at low pressure in a vacuum chamber, but a non-vacuum form of electron beam allows welding to be carried out outside the chamber. The equipment requirements include the electron emitter, electromagnetic control systems, the vacuum chamber and pumps etc. These are all highly sophisticated and very expensive. The process may be used for welding a range of ferrous and non-ferrous alloys. It is most suited to welding thick section in a single pass using square-edged butt joints. Joint design to provide integral filler and backing is of critical importance as is high tolerance machining to ensure close fitting. The process tends to be used in specialised industries such as aerospace, nuclear, and power generation. The main safety issues are high voltage power, X-ray emission, and vacuum conditions.
|
