clecture electron beam welding

lecture electron beam welding

Introduction The principles of electron beam generation and control were discussed in the early 1900's and by 1930 these principles had been used to construct electron microscopes. In the 1950's the use of electron beams for welding was made a commercial reality and the process was developed over the following decade into a very useful joining process Electron Beam Welding Principle The principles of electron beam generation and control were discussed in the early 1900's and by 1930 these principles had been used to construct electron microscopes. In the 1950's the use of electron beams for welding was made a commercial reality and the process was developed over the following decade into a very useful joining process Electron Beam Welding Modes of operation The earliest electron beam systems operated with a working chamber vacuum of 10-3 torr but recent developments have allowed the workpiece to be held under less vacuum or even at atmospheric pressure. In all cases the electron gun is operated under high vacuum but a series of seals and differential pressure enclosures is used to enable the work piece to be at a higher pressure than the gun. There are currently three main operating modes: - high vacuum (10-3 or less) - medium vacuum - non vacuum Electron Beam Welding Equipment The EBW system consists of: - an electron gun and beam delivery system - a power source - vacuum chamber and pumping equipment - work handling equipment Electron Beam Welding Features of the electron beam welding process The main features of EBW are: - the beam is produced and the process is normally conducted in a vacuum - the energy conversion (electrical to thermal) is very efficient - the power density at the workpiece is high -the beam can be magnetically deflected As a result of these basic features the process has the following advantages: - weld soundness is excellent - depth to width ratios of welds are high - keyhole operation is possible - travel speeds are high - beam access is good - heat input is low Electron Beam Welding Features of the electron beam welding process The main limitations of the process are: - the need to use a vacuum (long cycle times) - the high equipment cost - very good (machined) edge preparations are necessary - contaminants and surface coatings may damage the system Applications Electron beam welding may be applied to most engineering materials including; ferritic steels, stainless steels, aluminium alloys, reactive and refractory metals. Electron Beam Welding