The electron beam (eb) welding process is used in a variety of industries. Applications range from fully automated, high productivity and low cost automotive in-line part production to single part batch processes in the high-cost aircraft engine industry at the other end of the industrial spectrum. For those manufacturers and many others not specifically mentioned here, welding processes have to meet increasingly stringent standards that have become more prevalent over the years. In this regard, the eb welding process is well-positioned to provide industries with the highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
What is an Electron Beam?
In an electron beam welder electrons are "boiled off" as current passes through a filament which is in a vacuum enclosure.
An electrostatic field, generated by a negatively charged filament and bias cup and a positively charged anode, accelerates the electrons to about 50% to 80% of the speed of light and shapes them into a beam. Due to the physical nature of the electrons - charged particles with an extremely low mass - their direction of travel can easily be influenced by electromagnetic fields.
Electron beam welders use this characteristic to electromagnetically focus and very precisely deflect the beam at speeds up to 10 kHz. Recent machine developments make it possible even to go up to 200 kHz. With today's CNC controls, the beam focus as well as the beam deflection are part of the weld schedule and can be variably programmed along with other process parameters.
What Materials can be Welded with the EB?
Virtually all metals can be welded with an electron beam. Of course, the quality of welds depends on the metallurgy as well as other technical criteria, such as welding parameters and joint design. 
Filler material is not typically used to join the majority of components hence the metallurgy does not change. This makes the electron beam welding process simple and more cost effective. As with any rule, there are exceptions. There are materials where it is advantageous to use filler metals, e.g. avoiding weld cracking in 6000 series aluminum.
The use of 4000 series aluminum filler wire changes the metallurgy and prevents cracking. It is beyond the scope of this paper to detail the weldability of various metals; therefore, the following examples will focus on certain production applications.
Low to medium carbon micro-alloyed steels are typically used for manual transmission gear components in the automotive industry. Some of these materials are more prone to develop cracks after welding due to the significant hardness increases in the HAZ. These are caused by the quenching effect after welding and can be influenced by the width of the weld and the welding speed. Preheating the components is a common remedy used to substantially reduce hardness increases. It has become common practice in the automotive industry to preheat gears prior to welding in order to reduce the quenching effect in the HAZ. A welcome side effect of preheating in mass production is that welding speeds can be safely increased, making the process more economical.