AerMacchi (Italy) is responsible for the design, the manufacturing and the certi®cation of
the underwing pylons of the Euro®ghter Efa 2000. These items present severe performance
requirements; weight, stiness, static strength, fatigue and corrosion resistance, installation
compatibility and cost eectiveness were all goals to be achieved [8]. Several trade-o studies
were carried out on dierent structural con®gurations and manufacturing technology. The
results of these feasibility analysies led AerMacchi to explore the capabilities of the EBW
process applied to the 7050-T7451, an aluminium alloy that, as all the 7xxx alloys, has poor
weldability characteristics. On the other hand, the mechanical properties of more weldable
aluminium alloys, such as the 6xxx series, were not consistent with the performance required
for this structure.
The set-up of the welding process required long experimentation, not least because many
factors in¯uence the quality of the welded joint; these are, for example, the beam current, the
focus current, the welding speed, the oscillation of the beam across the welding direction and
the thickness of the joint. A number of plates welded during the quali®cation process were
supplied to the Department of Aerospace Engineering of the University of Pisa, to carry out
tests on the susceptibility to stress corrosion of the welded material, as well as to characterize
the residual stresses acting in the welded plates. The present paper describes the results of these
activities.