Suite of technologies – Alloys
Having created the majority of aviation alloys flying today, Alcoa is developing and introducing next-generation products that continue to offer optimum solutions for manufacturability, weight savings, structural integrity, damage tolerance, corrosion resistance and recyclability.
One focus at Alcoa has been on evolving a portfolio of new aluminum plate offerings for use in aircraft internal structures such as ribs, frames and bulkheads. These products include two new 7xxx alloys: 7085-T7451, developed for very thick applications (4-7 inches), which provides significant improvements in both strength and toughness, with excellent corrosion resistance; and C85T-T7651/-T7451 plate, developed for a range of thicknesses (1 to 6 inches), with substantially higher strength with similar or better toughness over incumbent 7050 plate in a given temper.
Among the company’s third-generation aluminum-lithium alloys is Al-Li 2099 (also designated C460), which is tailored for extruded products in high-strength applications requiring low density, high stiffness, superior damage tolerance, excellent corrosion resistance and weldability.
Extrusions made with alloy 2099 exhibit very good machining, forming, fastening, and surface finishing behavior in production. Such extrusions can replace 2xxx, 6xxx, and 7xxx aluminum alloys for applications such as statically- and dynamically-loaded fuselage structures, lower wing stringers and stiffness-dominated designs.
Alcoa’s 2099 alloy is commercially available and already has been adopted for structural applications on jetliners.
Aluminum-lithium solutions from Alcoa also include the 2199 alloy, which is tailored for use in sheet and plate on aircraft fuselages and in lower wing skin applications. Weight savings of nearly 20 percent can be realized with Al-Li 2199 due to its higher modulus, strength, lower density, and lower spectrum fatigue crack growth rates.
Alcoa has made significant production quantities of the Al-Li 2199 alloy – including full-sized samples, and material specifications exist for final evaluation by aircraft manufacturers for their future production applications.
As part of Alcoa’s capability to provide a portfolio of solutions, the Al-Li 2199 and Al-Li 2099 alloys can be combined for innovative lower wing applications on new aircraft – including the use on the successors to today’s single-aisle jetliners.
Another new Alcoa product is the aluminum-lithium S-4 alloy, tailored for wing and fuselage skins – offering lower density, higher-damage tolerance, and higher strength than incumbent alloys. When used in fuselages, its improved corrosion resistance eliminates the need for protective cladding. Mature specifications have been developed through Alcoa’s preparation of S-4 sheet production lots, which are ready for customer evaluation.