Alcoa introduced alloy 7055 in the -T7751 temper for plate and the -T77511 for extrusions in 1991. This new 7XXX alloy was specifically developed for use in compression-dominated structures and provides advantages over alloy 7150 in compressive and tensile strengths while maintaining other important properties such as fracture toughness and corrosion resistance. Alloy 7055-T7751 plate is available in thicknesses from 0.375 in. (9.53mm) to 1.25 in. (31.75mm) in widths up to 110 in. (2.79m). Alloy 7055-T77511 extrusions are available with wall thicknesses from 0.5 in. (12.7mm) to 2.5 in. (63.5mm) with a maximum circle size of 10 in. (254mm).

Alloy 7055 in the -T77 temper is best suited for applications where compressive strength is the critical design criteria such as upper wing structures, horizontal stabilizer, and keel beams. Other potential applications include seat and cargo tracks. When compared to 7150-T651 or -T7751, 7055-T77 typically provides a 7 to 10% increase in specific minimum compressive and tensile yield strength. The advantage of increased compressive strength of alloy 7055 permits significant weight savings when compared to alloy 7150.

CHEMICAL COMPOSITION LIMITS (WT.%)
                     Alloy 7150 Alloy 7055
Si . . . . . . . . . . . 0.12         0.10
Fe . . . . . . . . . . . 0.15        0.15
Cu . . . . . . . . . . . 1.9-2.5    2.0-2.6
Mn. . . . . . . . . . . 0.10        0.05
Mg. . . . . . . . . . . 2.0-2.7    1.8-2.3
Cr . . . . . . . . . . . 0.04        0.04
Zn . . . . . . . . . . . 5.9-6.9    7.6-8.4
Zr . . . . . . . . . . . 0.08-0.15 0.08-0.25
Ti . . . . . . . . . . . . 0.15       0.06
Others, each . . . . 0.05        0.05
Others, total . . . . 0.15        0.15
Balance . . . . . . . Aluminum Aluminum
Note: Value maximum if range not shown

MECHANICAL PROPERTIES (ROOM TEMPERATURE)
TYPICAL PROPERTIES (DESIGN ALLOWABLE DATA EXISTS)
                     1 in. (25.4mm) Plate           1 in. (25.4mm) Extrusion
                    7150-T7751 7055-T7751   7150-T77511 7055-T77511
Ftu, ksi (MPa)
L                      88 (607)    92 (634)             94 (648)    97 (669)
LT                    88 (607)    93 (641)             86 (593)    91 (627)
Fty, ksi (MPa)
L                      83 (572)    89 (614)             89 (614)    95 (655)
LT                    82 (565)    89 (614)             82 (565)    89 (614)
Fcy, ksi (MPa)
L                      82 (565)    90 (621)             92 (634)    97 (669)
LT                    87 (600)    94 (648)
e, percent
L                      12             11                     12              11
LT                    11             10                       9              10