7075 vs 7050 Aluminum: Choosing the Right High-Strength Alloy
By NOX METALS
7075 and 7050 both serve high-strength aluminum applications. Choosing between them requires the full alloy, temper and product specification. A strength number or plate thickness alone cannot decide whether one can replace the other. Start with the drawing, then compare the material and documentation each supplier can actually deliver.
Where thick-section performance matters
7050 is less sensitive to quench rate than 7075, which makes it useful in thick aerospace plate. Loading direction, fracture toughness and resistance to stress corrosion cracking also matter. There is no universal thickness at which every 7075 part must become 7050: the approved design and its material allowables determine that choice.
Compare tempers as well as alloys
7075-T651, 7075-T7351, 7050-T7451 and 7050-T7651 are separate purchasing requirements. T7351 is an overaged 7075 plate temper. Within the two 7050 tempers, T7451 prioritizes stress-corrosion resistance, while T7651 provides higher typical strength. Do not treat T7651 as an older name for T7451.
What the stress-relief suffix tells you
The 51 suffix identifies stress relief by stretching. It does not mean compression in T7351 and stretching in T7451. Stretching reduces residual stress; it does not guarantee that a heavily pocketed or thin-walled part will remain flat. Plan workholding, machining allowance and the roughing sequence around the finished geometry.
Typical properties are not acceptance limits
Kaiser lists typical longitudinal tensile/yield strengths of 76/68 ksi for 7050-T7451 and 80/71 ksi for T7651. These are reference values, not guaranteed minimums for every thickness and orientation. Use the drawing’s material specification and the actual mill certificate for acceptance, and the approved engineering data for design.
Specify what must arrive
AMS 4050 covers 7050-T7451 plate. State the required revision and any additional inspection requirements on the order. A heat-treatment process standard is not a substitute for a plate material specification.
- Alloy, temper, plate thickness and the finished blank’s width and length.
- Grain direction and enough stock for facing and finish machining.
- Required material specification, inspection, origin and certification.
- Quantity, delivery location and the date the material is needed.
Compare the cost of the required blank
Compare current quotes for the same dimensions, quantity, certification and delivery terms. A fixed percentage premium for one alloy hides differences in stock, cut yield and shipping. If an alternative looks attractive, obtain engineering approval for the substitution before purchasing it.
Use the exact alloy and temper on the drawing to select the material page, then confirm the offered sizes and certification. Choose an alternative only through the project’s material approval process.