Electron Beam Welding of Precipitation Hardening Copper Alloy

The complex design of the probe coupled with material thicknesses from 2mm to less than 1mm demanded a precise welding process with minimal heat input and distortion. Electron beam welding has long be used for these types of challenging applications which require a precise welding process.

The joints on the probe body and sensors are a mixture of fully penetrating and partial penetration welds into backing. Due to the nature of the environment the probe will be used in and the need to pressure test the completed welds to ~50Bar, each joint must meet exacting quality requirements.

The prototype component was assembled in a bespoke fixture designed and manufactured by CA with input from TWI. The fixture required careful design to accommodate the sensor tubes and additional thermocouple wiring. The assembled unit was secured in TWI’s 4kW 60kV electron beam welding facility which has full cnc control of all major axes (mechanical and electrical) and is fitted with TWI’s digital multi-axis beam deflection system. High definition CCTV fitted to the telescope optics was used to accurately locate the joints to a tolerance of +/-20µm.

The final welding plan was a complex multistage approach, in some cases using a two stage overlapping method to control heat-input and realise high quality welds. The complex geometry of the sensor components required welding paths defined by TWI’s deflection system. After successfully completing the welding plan, the probe was subjected to extended testing at CA and has produced promising results leading to further work on additional prototypes.

For more information on our electron beam technologies, please contact us.