clecture 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