24 July 2021 7000 Series Aluminum Alloy
7255 Aluminum Alloy Plate
Alcoa developed aluminum alloy AA 7255 plate for use in aerospace applications requiring very high strength and fatigue resistance. Compared to alloy 7075, 7150 and 7055 plate, alloy 7255 offers higher strength and improved fatigue resistance with similar or better fracture toughness and corrosion resistance.
Alloy 7255 plate is available in the plant-aged T7751 temper and in the W51 temper for user age forming to the T79E01* temper. The available thickness range for 7255 plate is 0.75 to 1.5 inches (19.0 to 38.1 mm).
Alloy 7255 plate can replace alloys 7075, 7150 and 7055 and other high strength plate alloys in applications requiring high tensile or compressive strength such as upper wing panels. The machining and fabrication characteristics of 7255 plate are the same or very similar to that of other high strength 7xxx plate products.
Chemical Composition:
| Chemical Elements | Metric | English |
|---|---|---|
| Aluminum, Al | 86.1 - 88.52 % | 86.1 - 88.52 % |
| Chromium, Cr | <= 0.04 % | <= 0.04 % |
| Copper, Cu | 2.0 - 2.6 % | 2.0 - 2.6 % |
| Iron, Fe | <= 0.09 % | <= 0.09 % |
| Magnesium, Mg | 1.8 - 2.3 % | 1.8 - 2.3 % |
| Manganese, Mn | <= 0.05 % | <= 0.05 % |
| Other, each | <= 0.05 % | <= 0.05 % |
| Other, total | <= 0.15 % | <= 0.15 % |
| Silicon, Si | <= 0.06 % | <= 0.06 % |
| Titanium, Ti | <= 0.06 % | <= 0.06 % |
| Zinc, Zn | 7.6 - 8.4 % | 7.6 - 8.4 % |
| Zirconium, Zr | 0.08 - 0.15 % | 0.08 - 0.15 % |
Mechanical Properties:
| Static Properties • 7255 Plate • Minimum Values (S or A-Basis) | ||||||
|---|---|---|---|---|---|---|
| Alloy/Temper | Dir. | 7255-T7751 (AMS 4463) | 7255-T79E01 (S or A est.*) | 7075-T651 (AMS 4045) | 7150-T7751 (AMS 4252) | 7055-T7751 (AMS 4206) |
| Thickness, Inch (mm) | 0.75 – 1.50 (19.0 – 38.1) | 0.50 – 1.00 (12.7 – 38.1) | 1.00 – 2.00 (25.4 – 50.8) | 0.75 – 1.50 (19.0 – 38.1) | 0.50 – 1.50 (12.7 – 38.1) | |
| Tensile Strength, Ftu, ksi (MPa) | L | 91 (627) | 88 (607) | 76 (524) | 84 (579) | 89 (614) |
| LT | 91 (627) | 88 (607) | 77 (531) | 84 (579) | 89 (614) | |
| Tensile Yield, Fty, ksi (MPa) | L | 88 (607) | 86 (593) | 69 (476) | 78 (538) | 86 (593) |
| LT | 86 (593) | 84 (579) | 67 (462) | 77 (531) | 85 (586) | |
| Elongation, %, 4D | L | 9 | 8 | na | 8 | 7 |
| LT | 7 | 7 | 6 | 8 | 8 | |
| Comp. Yield, Fcy ksi (MPa) | L | 88 (607) | 86 (593) | 66 (455) | 77 (531) | 86 (593) |
| Fracture Toughness • 7255-T7751 | |||
|---|---|---|---|
| Alloy/Temper | Orient. | KIc Minimum ksi√in (MPa√m) | KIc Typical ksi√in (MPa√m) |
| 7255-T7751 | L-T | 22 (24) | 24 (26) |
| T-L | 21 (23) | 24 (26) | |
| 7055-T7751 | L-T | 22 (24) | 24 (26) |
| T-L | 21 (23) | 24 (26) | |
| 7150-T7751 | L-T | 22 (24) | na |
| T-L | 20 (22) | na | |
| 7075-T651 | L-T | na | 26 (29) |
| T-L | na | 22 (24) | |