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Thursday, June 10, 2004 - 10:30 AM
AFS3.4

Benefits from the Use of Extruded 2196 and C460 Al-Li Alloys in A380 Floor Beam Applications

V. C. Guillaumin, Airbus France, Toulouse, France

During the last 30 years, aluminum-lithium alloys have been developed with the objective to offer more fuel-efficient and high performance aircraft or aerospace structures. Indeed, reducing density without compromising strength, toughness and corrosion resistance has been shown to be the most efficient way to accomplish this goal. Lithium, can reduce the density of aluminum by three percent and increase the elastic modulus by six percent for every weight percent of lithium added. Airbus has been already contemplating first generations of aluminum-lithium alloys for several applications on A340 (fuselage, wing skins, stringers, frames, seat rails). The main identified issues such as thermal stability, anisotropy and crack deviation raised by these alloys, 8090 T8511, 2091 T851 led to give up. The improvement in the third aluminum-lithium alloys generation overcomes these concerns by reduction of lithium content together with optimization of other alloying elements contents to modify the precipitate types. C460 from Alcoa and 2196 from Pechiney, developed for extrusion applications, belong to this the third aluminum-lithium alloys generation. Both alloys exhibits higher or equal properties when compared to conventional 7175 T73511 alloy with improved corrosion resistance. These alloys have been successfully qualified for A380 floor beams applications with a significant weight saving. They are currently considered for A380 bottom wing stringer applications that could offer some additional weight saving. In the frame of A380 freighter development, new aluminum-lithium thin products are considered for fuselage skin sheet application. Today, Airbus R&T considers aluminum-lithium alloys as being the spearhead of metal products to maintain competitiveness of metallic structures against composite ones.