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The objective of this study is to determine the effect of solution treatment temperature, quenching media, and various machining sequences on the warpage behavior of aluminum 7249 alloy aged to T6 and T7¢ tempers. Large extrusions of 7249 aluminum alloy with fins were cut into 108 ''T'' sections. The samples were solution-treated, aged, and machined. Three solution temperatures (445, 474, and 505°C), two quenching media (water and 20% polyalkylene glycol), two aging treatments (T6 and T7¢), and three machine sequences were used. The flatness of the samples was measured on the surfaces orthogonal to the z-axis. Three points were on top of both shoulders (six total), six were at the bottom of the sample, and six were on the top of the fin, in the cases where the fin was not milled off. They were then averaged together by surface to represent the overall warpage of each sample.

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The recently developed aluminum alloy 6013-T6 has been selected for the fuselage skin and other applications on the u.s. Navy's P-7 A airplane, in place of the traditional 2024-T3 clad sheet. Alloy 6013-T6 is naturally corrosion resistant, like the well-established alloy 6061, and hence is used unclad. Its fatigue strength, fatigue crack growth and fracture toughness compare favorably with 2024-T3. Replacement of alloy 2024 with alloy 6013 also reduces manufacturing costs for formed parts, because 6013 is readily formed in the T4 temper, then simply aged to T6, thus avoiding the costly heat treatments and straightening required for alloy 2024.