7075-T7351 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 | 0.1015 lb/in³ (2.81 g/cm³) | Nominal reference density |
| Ultimate tensile strength | 73 ksi typical | Representative T7351 plate value; confirm thickness and direction |
| Yield strength | 63 ksi typical | Representative value; not a substitute for design allowables |
| Elongation | 13% typical | Varies by thickness and specimen orientation |
| Hardness | 135 HB typical | Reference comparison with T651 |
History of 7075
7075 came from the rapid development of zinc-magnesium-copper aluminum for aircraft in the 1930s and 1940s. Peak-aged versions delivered extraordinary strength, but service experience also exposed the vulnerability of highly stressed 7xxx products to stress-corrosion cracking. Metallurgists responded with controlled overaging treatments that changed precipitate structure and improved resistance.
The T73 family represents that corrosion-resistance response. In T7351 plate, the alloy is solution heat treated, stretched for stress relief, and overaged. The “51” retains the dimensional-stability benefit needed by machine shops, while the T73 aging path distinguishes its service behavior from T651. Its history is therefore less about a new chemistry than about learning to manage a strong alloy over an aircraft lifetime.
- 1930s–40s
7075 enters aircraft structures
The alloy establishes a new high-strength aluminum benchmark for airframe design.
- Postwar era
Overaged tempers mature
Service-driven research improves resistance to stress-corrosion cracking in highly stressed 7xxx products.
- Today
T7351 serves durability-led designs
It remains a standard option where stress-corrosion performance outranks the last increment of strength.
T7351 versus T651
Both tempers use stretch stress relief, so both are suitable starting points for substantial machining. The main difference is the aging treatment. T651 is closer to peak strength. T7351 is overaged, lowering tensile and yield values while improving resistance to stress-corrosion cracking. That is a performance trade, not a quality ranking.
Do not select from a single strength number. Consider the governing allowable, part thickness, grain direction, sustained tensile stress, coating system, environment, inspection plan, and service life. If the print says T7351, a T651 cert with higher tensile strength is not an upgrade; it is the wrong temper.
Machining and surface protection
T7351 cuts much like other high-strength 7075 plate. Use rigid tooling, positive geometry, reliable chip evacuation, and a roughing sequence that removes material from opposing faces. Large monolithic parts still benefit from an intermediate rest before final dimensions, even though the plate was stretched.
Improved stress-corrosion resistance does not make the alloy immune to corrosion. Protect surfaces where the design requires it, seal end grain, isolate dissimilar metals, and avoid moisture traps. Follow the drawing for anodize, conversion coating, primer, and fastener installation rather than relying on a generic shop finish.
What to verify on the cert
Order the exact temper and specification—commonly AMS 4078 for aerospace plate or ASTM B209 for commercial requirements. Record nominal thickness, cut size, quantity, and any additional inspection, origin, ultrasonic, fracture, or traceability clause from the drawing.
On receipt, verify 7075-T7351, plate product form, specification and revision, heat or lot number, and reported results in the required test direction. Segregate it from T651 inventory. A visual inspection cannot tell the two tempers apart, and mixed stock defeats the reason T7351 was specified.
Specifications and purchase callouts
The controlling drawing decides which specification applies. A similar alloy name or typical-property table does not demonstrate compliance.
- ASTM B209
- SAE AMS 4078
- AMS-QQ-A-250/12 (legacy federal callout)
Frequently asked questions
Why choose 7075-T7351 instead of T651?
Choose T7351 when improved stress-corrosion resistance is more important than the higher peak strength of T651. This is common in thick, highly stressed aerospace parts or other long-life structures exposed to sustained load and a corrosive environment.
Is 7075-T7351 weaker than T651?
Its tensile and yield values are lower because it is intentionally overaged, but “weaker” misses the design purpose. T7351 trades some static strength for improved stress-corrosion behavior. Use the allowable and temper required by the engineering authority.
Can T651 be substituted when T7351 is unavailable?
Not without engineering approval. Higher peak strength does not reproduce T7351 stress-corrosion performance, and the substitution can undermine the service-life reason behind the drawing callout. Treat the two tempers as distinct materials.
What specification covers 7075-T7351 plate?
AMS 4078 is a common aerospace plate specification, and ASTM B209 may govern commercial aluminum plate. Legacy drawings may cite AMS-QQ-A-250/12. The purchase order should follow the exact specification and revision required by the drawing.
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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