Surfi-Sculpt®: The Metallurgical Implication of Electron Beam (EB) Surface Sculpting in Hyper-Joints for Composite to Metal Joining

The significant weight reduction offered by composite materials has led to an increase in their usage within the aerospace industry. However, in airframes composites are often required to be joined to metal components which are very challenging owing to their different thermo-physical properties. One approach of improving joint performance is to engineer locking features on the metal part which penetrate into the fibre layers to reinforce adhesively bonded joints. Such hybrid joints are known as “hyper-joints”. The Surfi-Sculpt process is one of several hyper-joint manufacturing routes under investigation, through which these features can be made. It is acknowledged that the Surfi-Sculpt process will alter the microstructure of the substrate material and that the built features will not have the same structure as the wrought substrate. A range of EB structured surfaces (with features of between 0.8 and 1.5 mm in height) have been produced in a Ti-6Al-4V substrate and characterised to assess the impact of the process on the metallurgy of the surface features. The extent to which the surface is modified is related to the design of the beam pattern and the EB parameters employed in the process. These results provide an insight to allow the generation of surface structuring patterns with minimal metallurgical impact.