Notwithstanding successive optimizations and refinements, the alloy system of choice for the fuselage skin of commercial aircraft has long been Al-Cu-Mg-Mn in the T3 temper. This product displays exceptional damage tolerance, particularly in its more recent incarnations (2524, 2056). More recently, products demonstrating very similar mechanical properties but with additional technological advantages such as weldability (6013-T6, 6056-T6) and corrosion resistance (6056-T78) have been successfully introduced. However, a requirement for a significant strength increment with respect to the above-mentioned products is increasingly being expressed.

This paper will present some options developed by Pechiney Aerospace that enable very significant increases in strength with equivalent toughness and resistance to fatigue crack growth. Two major approaches have been explored: the addition of silver to 2xxx-T8 products, which enables 30-50% increases in strength for identical toughness; the development of very high damage tolerance 7xxx alloys for such applications. Detailed property balances thus achieved will be presented in comparison with the incumbent products. In addition, the metallurgical principles underlying these significant increases in strength-toughness balance will be discussed. The weight savings enabled by these new products will be illustrated. Finally, some design approaches to mitigate some of the potential disadvantages of these solutions with respect to 2024-T3 will also be proposed.