Electron Beam Welding Welding Technology/4.3 Electron Beam Welding

Electron Beam Welding W.C.Roentgen in late 1800s found that when a beam of electrons were suddenly stopped by impact with a target, then it starts heating and melting the target. The first practical Electron beam welding machine was developed by the German physicist Dr. Karl-Heinz Steigerwald which began operation in 1958. Welding Technology/4.3 Electron Beam Welding

Electron Beam Welding Electron-beam welding (EBW) is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. The workpieces melt and flow together as the kinetic energy of the electrons is transformed into heat upon impact. It is fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. Free electrons in vacuum can be accelerated, with their paths controlled by electric and magnetic fields. Welding Technology/4.3 Electron Beam Welding

Principle This welding works on same principle of electron beam machining. This process uses kinetic energy of electrons to produce heat. This heat is further used to weld two welding plates. When a high jet of electrons strike at welding plates, its kinetic energy converts into heat energy. This heat energy is sufficient to fuse two metal plates together to form a weld joint. Electron beams are composed of electrons that are charged particles having a rest mass of 9.1x10-31 kg and can be accelerated in electron guns to relativistic velocities, giving them high kinetic energies. At 10 kV (13 hp), electrons travel at approximately 20% of the speed of light, while at 200 kV (270 hp) they travel at approximately 70% the speed of light Welding Technology/4.3 Electron Beam Welding

Principle Electron beam welding process is carried out in vacuum. In this process, electrons are emitted from the heated filament called electrode. These electrons are accelerated by applying high potential difference (30 kV to 175 kV) between cathode and anode. The higher the potential difference, the higher would be the acceleration of the electrons. The electrons get the speed in the range of 50,000 to 200,000 km/s. When high kinetic energy electron beam strikes the workpiece, high heat is generated resulting in melting of the work material. Molten metal fills into the gap between parts to be joined. Welding Technology/4.3 Electron Beam Welding

Electron beam weld setup An EBW set up consists of the following major parts Electron Gun Power Supply Unit Vacuum Chamber Work piece Handling Device . Welding Technology/4.3 Electron Beam Welding

Welding Technology/4.3 Electron Beam Welding

Process Parameters Major Process Parameters are Accelerating voltage Beam current Welding speed Beam Focusing Welding Technology/4.3 Electron Beam Welding

Applications Mostly used in joining of refectory materials like columbium, tungsten, ceramics. High Precision Welding of electronics components. High precision welding of nuclear fuel elements. Special alloy components of jet engines. Pressure vessels for rocket. Joining of Dissimilar metals. Welding of Titanium medical implants. Difficult to melt and weld metals Welding Technology/4.3 Electron Beam Welding

Advantages High penetration to width can be obtained. High welding speed is obtained. Material of high melting temperature can be welded. Superior weld quality due to welding in vacuum i.e. welds are corrosion free. Distortion is less due to less heat affected zone. Inaccessible joints can be made. Very wide range of sheet thickness can be joined (0.025 mm to 100 mm). Welding Technology/4.3 Electron Beam Welding

Disadvantages Very high equipment cost. Transportation of equipment is not easy. Vacuum is required. Skilled person is needed. X-rays generated during welding 60 kV 4 kW (610 mm3) electron beam welder including CNC controlled work manipulation systems £220,000.00 i.e. 17609882.40 INR (1 £ = 80.02 INR) Welding Technology/4.3 Electron Beam Welding