7050-T7451 Aluminum Plate properties at a glance
Values labeled typical are orientation- and section-dependent references, not design allowables. Use the current governing specification and the supplied mill certificate for acceptance.
| Property | Reference value | How to use it |
|---|---|---|
| Density | 0.1022 lb/in³ (2.83 g/cm³) | Nominal reference density |
| Ultimate tensile strength | 76 ksi typical | Representative T7451 plate value; thickness and direction matter |
| Yield strength | 68 ksi typical | Representative value; consult AMS 4050 and design allowables |
| Elongation | 11% typical | Varies with thickness and test orientation |
| Hardness | 140 HB typical | Reference value rather than a universal acceptance limit |
History of 7050
7050 was registered in the United States in 1971 during an era of increasingly large, integrally machined aircraft structures. Designers needed a 7xxx alloy that retained useful strength, toughness, and corrosion performance deeper into thick plate. Its zirconium-bearing chemistry and lower quench sensitivity helped answer the thick-section limitations encountered with earlier high-strength alloys.
By 1973, government-indexed technical work was already comparing 7050 with established aircraft alloys. The T7451 treatment pairs overaging for stress-corrosion resistance with stretch stress relief for machining stability. It became associated with wing center sections, bulkheads, spars, fuselage frames, and other parts whose size makes through-thickness behavior and residual stress as important as a headline tensile number.
- 1971
7050 is registered
The alloy enters the Aluminum Association wrought-alloy system as a U.S. development.
- 1973
Early comparative data is published
Technical evaluations compare the new alloy with established high-strength aircraft aluminum.
- Today
A thick-plate aerospace standard
7050-T7451 remains a deliberate choice for large, deeply machined structural components.
Why 7050 exists
7050 is not simply “another 7075.” It was built around large sections, where rapid quenching is harder and short-transverse performance becomes critical. Its chemistry and heat-treatment response support a combination of strength, toughness, and stress-corrosion behavior that makes it useful for thick aerospace structure.
T7451 prioritizes stress-corrosion resistance and stability. T7651 is an alternative 7050 temper that can provide higher strength with a different corrosion tradeoff. Do not collapse the two into a generic 7050 callout; use the temper, thickness range, specification, and allowables approved for the part.
Plan for a large machining blank
The “51” stretch relief helps a large plate blank hold shape, but deep pockets and thin webs can still release residual stress. Establish datum strategy before roughing, remove stock in balanced stages, support the work without forcing it flat, and leave time and material for a stable finishing operation.
Grain direction is central to high-strength plate design. Mark rolling direction before nesting parts and preserve it through saw cutting and machining. A cert value in the longitudinal direction does not describe short-transverse behavior, and rotating a critical part to improve material yield can change the controlling property direction.
Buy to the drawing and inspection plan
Aerospace 7050 purchases often include more than alloy and temper: AMS 4050 revision, thickness, dimensions, grain orientation, ultrasonic class, fracture-toughness or stress-corrosion requirements, origin, and full heat or lot traceability may all matter. Flow every drawing note into the purchase order.
Compare the received cert with the ordered specification and test direction, not with a generic internet property table. Keep the heat identity attached to every remnant. Thick plate can represent substantial material and machining value, so traceability must survive cutting, storage, and issue to the machine.
Specifications and purchase callouts
The controlling drawing decides which specification applies. A similar alloy name or typical-property table does not demonstrate compliance.
- SAE AMS 4050
- ASTM B209 where specified
- Customer-specific ultrasonic and fracture requirements where applicable
Frequently asked questions
What is 7050-T7451 used for?
Common applications include wing center sections, bulkheads, spars, fuselage frames, and other large machined aerospace structures. It is selected where thick-section toughness and stress-corrosion performance matter alongside high strength.
How is 7050 different from 7075?
7050 was developed for stronger thick-section performance and lower quench sensitivity, with good toughness and stress-corrosion behavior in large plate. 7075 remains widely available and can be the better fit in thinner or strength-led applications.
What does T7451 mean?
It identifies a solution-heat-treated, stretched, and overaged condition. The overaging supports stress-corrosion resistance, while the 51 suffix identifies stretch stress relief used to improve dimensional stability during machining.
Which specification covers 7050-T7451 plate?
AMS 4050 is the common aerospace specification. Some commercial purchases may cite ASTM B209, and drawings can add ultrasonic, fracture, origin, or customer-specific requirements. Follow the exact controlling callout.
Primary references
Technical standards change. These sources support the history and reference discussion; obtain the current specification revision for design or acceptance work.
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