K. P. Smith, Alcan Rolled Products, Ravenswood, WV; V. B. Dangerfield, Pechiney Rolled Products, Ravenswood, WV; D. Chellman, Lockheed Martin Aeronautical Systems, Marrietta, GA; E. S. Balmuth, Lockheed Martin Aeronautics, Fort Worth, TX

Summary:

Machining of aircraft structural components from thick rolled plates is often an avenue for lowering the overall cost of aircraft production through elimination of built-up structures and by providing alternative solutions to forged products. The 7040 alloy was first developed in the T7451 temper, primarily to offer significantly improved toughness over similar strength 7050 T7451 for thick plates in such applications. A recent project with Lockheed Martin Aeronautics led to the development of 7140 T7451 providing increased strength over 7040 T7451 temper, while still maintaining significantly higher toughness than 7050 T7451 and similar stress corrosion cracking (SCC) resistance.

Applications for 7140 T7451 may include wing spars and ribs, bulkheads, fuselage frames and various other fittings in aircraft structure. The plate product will be initially offered from 4 to 10 inches thick.

Over the last 7 months, an extensive testing program has been completed for submission of mechanical property data to MMPDS. In addition, Lockheed Martin Aeronautics has performed evaluation testing and has written a specification for the plate material, which will be used for aircraft structural components. Some producibility trials involving finishing and machining studies on 7140 T7451 plate have been conducted and will be described in the presentation.