A fastener for assembling at least two structural elements having an aperture, may have a fastener comprising an enlarged head (12) and a shank (14) exhibiting, prior to fitting, an outside diameter (D1) greater than an inside diameter (DS) of the aperture, and a locking portion comprising a screw thread or annular grooves. The fastener further comprises a lubricating sacrificial ring (40) on the exterior surface of the fastener, extending at least between a distal end of the shank and a proximal end of the locking portion, said ring having, before the fastener is fitted into the structure, an outside diameter greater than a diameter of the aperture. The sacrificial ring comprises a polymer resin forming a matrix encapsulating dispersant molecules and oil molecules.
The fastener assembly may apply to the assembly of aircraft structures.