TWI Industrial Member Report Summary 965/2010
By C Punshon
Reduced pressure electron beam welding (RPEBW) using local sealing and pumping has been identified as an attractive alternative to high vacuum, in-chamber EBW. The welding process use a stable, reproducible and reliable beam, which can penetrate and weld metallic materials of greater than 150mm thickness in a single pass, whilst producing similar weld profiles to those achieved with high vacuum EBW, even for working distances between 50-500mm. Coupled with a functioning local sealing and pumping arrangement, providing the necessary reduced pressure conditions, this EB process variant has the potential to open up new spheres of welding applications, where the size of components and logistics of manufacture preclude the use of a vacuum chamber.
Applications in thick section materials that could benefit from this development are emerging in fields such as offshore (oil and gas and offshore wind energy), nuclear power (fission and fusion), fabrication of large pieces previously obtained as castings or monobloc forgings and manufacture of large components for the construction industry.
Following a review of previous work and a design study, an experimental mobile seal system has been established at TWI and has illustrated that with local sealing and pumping, the pressure levels required for successful high power EBW at reduced pressure (1mbar) can be sustained whilst moving at a typical welding speed. The next step identified was to develop this further and demonstrate the system in an industrial environment with a commercial EB generator. It is anticipated that the successful development and implementation of this method will lead to more widespread and greater exploitation of this welding process technology.
- Develop TWI's local, mobile vacuum seal for RPEBW re-visiting the design and materials used.
- Demonstrate the system in an industrial environment with a commercial EB generator.