7050-T7451 (AMS 4050)
Solution heat-treated, stretched about 1.5 – 3 % and overaged. The usual temper for thick plate, giving good stress-corrosion resistance in the short-transverse direction. Covers plate across a very wide thickness range.
Aerospace · thick 7xxx plate
7050 Aerospace Aluminium Plate (T7451 / T7651)
7050-T7451 is the standard thick plate for machined aircraft structure: wing spars and ribs, fuselage frames and bulkheads, and large fittings cut from plates up to about 150 mm thick and more. It combines high strength with good fracture toughness and stress-corrosion resistance through the full thickness. Metline supplies 7050 plate in T7451 (AMS 4050) and T7651 (AMS 4201), cut to size and certified, to aerospace buyers worldwide.
- Alloy
- 7050 (Al-Zn-Cu-Mg-Zr)
- Tempers
- T7451, T7651
- Thickness
- About 6 – 200 mm and up
- Standards
- AMS 4050 · AMS 4201 · ASTM B209
Why 7050-T7451 became the default thick aerospace plate
Modern airframes are increasingly machined from solid plate: a single wing rib or fuselage frame can start as a plate weighing hundreds of kilograms and end as a part weighing a tenth of that. The plate must be strong in the centre as well as at the surface, stay flat as most of it is machined away, and resist stress-corrosion cracking across its thickness. 7050-T7451 was designed to do all three.
Two features make it work. Zirconium, in place of the chromium used in 7075, forms fine dispersoids that keep the grain structure unrecrystallised and make the alloy far less sensitive to quench rate, so the centre of a thick plate still reaches high strength. The T7451 temper then stretches the plate to remove quench stresses and overages it to a condition that balances strength against resistance to stress corrosion and exfoliation.
Low iron and silicon limits (0.15 % and 0.12 % maximum) give 7050 better fracture toughness and fatigue performance than 7075. For these reasons 7050-T7451 plate is used on most current commercial and military aircraft for machined internal structure, while 7075 plate is now chosen mainly for thinner, less critical parts or where cost dominates.
7050 chemical composition (wt %)
Limits are the registered Aluminum Association values used by AMS 4050, AMS 4201, ASTM B209 and EN 573-3 (EN AW-7050). The mill certificate gives the actual analysis for each cast.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | — | 0.12 | Held very low for fracture toughness |
| Iron (Fe) | — | 0.15 | Held very low; fewer coarse intermetallics |
| Copper (Cu) | 2.0 | 2.6 | Raises strength and stress-corrosion resistance in T7 tempers |
| Manganese (Mn) | — | 0.10 | Residual |
| Magnesium (Mg) | 1.9 | 2.6 | Forms MgZn2 with zinc |
| Chromium (Cr) | — | 0.04 | Deliberately low; zirconium replaces it |
| Zinc (Zn) | 5.7 | 6.7 | Main strengthening element |
| Titanium (Ti) | — | 0.06 | Grain refiner |
| Zirconium (Zr) | 0.08 | 0.15 | Controls grain structure and lowers quench sensitivity |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 87.3 – 90.3 % |
7050 is about 5 % denser than 6061 (2.83 against 2.70 g/cm³). Allow for this when estimating plate weights.
Mechanical properties of 7050 plate
Typical values describe material of moderate thickness. AMS 4050 and AMS 4201 set minimum tensile, yield and elongation values in the longitudinal, long-transverse and short-transverse directions, and those minimums fall as plate thickness rises. Design allowables come from those specified values, not from typical data.
| Temper | Tensile strength (typical) | Yield strength (typical) | Elongation | Hardness |
|---|---|---|---|---|
| T7451 (AMS 4050) | 524 MPa / 76 ksi | 469 MPa / 68 ksi | About 11 % | About 140 HB |
| T7651 (AMS 4201) | About 550 MPa / 80 ksi | About 490 MPa / 71 ksi | About 10 % | About 145 HB |
Short-transverse properties matter most for thick plate. Strength and ductility through the thickness are lower than in the rolling direction, so parts with loads across the plate thickness (lugs, fittings, frames with integral attachments) are designed to short-transverse allowables, and the T7451 temper is chosen to keep stress-corrosion risk low in that direction.
Physical properties
- Density
- 2.83 g/cm³ (0.102 lb/in³)
- Modulus of elasticity (tension)
- About 71.7 GPa (10,400 ksi)
- Shear modulus
- About 26.9 GPa
- Thermal conductivity
- About 155 – 160 W/m·K (T74 tempers)
- Electrical conductivity
- About 39 – 44 % IACS (T74 / T76), used as a check on the overaged temper
- Coefficient of thermal expansion
- About 23.5 µm/m·°C (20 – 100 °C)
- Melting range
- About 490 – 630 °C
T7451 versus T7651 plate
7050-T7651 (AMS 4201)
Stretched and moderately overaged for higher strength with good exfoliation resistance. AMS 4201 covers plate 6.35 – 76.2 mm (0.250 – 3.000 in) thick. Often used for wing skins and parts loaded in the plane of the plate.
Other tempers
F and O are supply conditions for later heat treatment. T7452 belongs to hand forgings rather than plate, and older designs may call T73 or T7351 in other alloys.
7050 plate specifications and designations
| System | Designation / standard | Scope |
|---|---|---|
| SAE AMS | AMS 4050 | 7050-T7451 plate, solution heat-treated, stress-relieved and overaged |
| SAE AMS | AMS 4201 | 7050-T7651 plate, 0.250 – 3.000 in |
| ASTM / ASME | ASTM B209 | Aluminium and aluminium-alloy sheet and plate |
| Inspection | AMS-STD-2154 / ASTM B594 | Ultrasonic inspection, Class A or AA as ordered |
| Heat treatment | AMS 2772 | Heat treatment of aluminium-alloy raw materials |
| UNS | A97050 | — |
| European | EN AW-7050 (AlZn6CuMgZr) | EN 485, EN 573-3 |
| German Werkstoff | 3.4144 | — |
| Japan | A7050P | JIS H4000 |
Aircraft manufacturers add their own plate specifications with extra requirements, typically on fracture toughness, ultrasonic class, residual stress and grain structure. Quote the specification and revision from your drawing or purchase order so we can supply material certified against it.
7050 plate sizes and weights
Supply range
- Thickness
- About 6 mm to 200 mm; thicker plate by enquiry
- Common sheet sizes
- 1250 × 2500 mm, 1525 × 3660 mm (60 × 144 in), 2020 × 4020 mm
- Width and length
- Widths to about 2600 mm and long lengths by enquiry; saw-cut blanks to your nesting
- Imperial thickness
- 0.25 in to 6 in and above, in common 1/8 in or 1/4 in steps
- Cut pieces
- Saw-cut blocks and strips, for example 12 × 12 in or 24 × 36 in blanks
Thick 7050 plate is a high-value product. Cutting blanks close to the part envelope saves material and freight.
Weight is 2.83 kg per square metre for every millimetre of thickness. The plate weight calculator gives other sizes; set the density to 2.83 g/cm³.
| Thickness (mm) | kg per m² | 1220 × 2440 mm (kg) | 1525 × 3660 mm (kg) |
|---|---|---|---|
| 6.35 | 17.97 | 53.5 | 100.3 |
| 10 | 28.30 | 84.2 | 158.0 |
| 12.7 | 35.94 | 107.0 | 200.6 |
| 20 | 56.60 | 168.5 | 315.9 |
| 25.4 | 71.88 | 214.0 | 401.2 |
| 30 | 84.90 | 252.7 | 473.9 |
| 40 | 113.20 | 337.0 | 631.8 |
| 50.8 | 143.76 | 428.0 | 802.4 |
| 60 | 169.80 | 505.5 | 947.7 |
| 76.2 | 215.65 | 641.9 | 1203.6 |
| 100 | 283.00 | 842.4 | 1579.6 |
| 127 | 359.41 | 1069.9 | 2006.0 |
| 150 | 424.50 | 1263.7 | 2369.3 |
| 200 | 566.00 | 1684.9 | 3159.1 |
Inspection, tolerances and certification
What an aerospace 7050 plate order normally includes
- Dimensional tolerances
- ANSI H35.2 / ASTM B209 tables unless tighter limits are ordered; saw-cut blanks typically ±1 mm or as agreed
- Flatness
- Controlled by stretching; specified by the plate standard and checked on dispatch
- Tensile tests
- Per lot, in the directions required by the specification
- Fracture toughness
- KIc testing per ASTM E399 where the specification requires it
- Conductivity and corrosion
- Electrical conductivity check, with stress-corrosion and exfoliation testing as called up
- Ultrasonic
- Immersion testing to AMS-STD-2154 or ASTM B594, typically Class A, or AA for critical parts
- Certification
- EN 10204 3.1 certificate with chemistry and test data, traceable to cast and lot
Machining and processing 7050 plate
High-speed machining
Machines very well with sharp carbide tools at high spindle speeds. Large pocketing operations are routine; the stretched temper keeps distortion low, though removing more than about 90 % of the plate from one side may still need balanced roughing.
Distortion control
Rough both faces symmetrically, leave stock for a finishing pass after a rest period, and clamp lightly on the final cut. These steps matter more as part thickness falls.
Joining
Not suitable for arc welding. Assemblies are fastened, riveted or bonded. Friction stir welding is used in some aerospace and space structures after qualification.
Forming
Limited cold formability in T7451. Creep forming or age forming is used for curved wing panels; small bends should use generous radii.
Surface treatment
Chromic, sulphuric or boric-sulphuric anodising, or conversion coating and primer. Shot peening is often added to fatigue-critical surfaces.
Temperature
Keep service temperature below about 120 °C to avoid further overageing and loss of strength.
Where 7050 plate is used
- Wing structure: spars, ribs, bulkheads and integrally stiffened panels
- Fuselage: frames, floor beams, bulkheads and door surrounds machined from thick plate
- Fittings: wing-to-body, engine-mount and landing-gear support fittings
- Helicopters: transmission decks, frames and rotor-support structure
- Space: launch-vehicle rings, adaptors and machined panels
- Defence and tooling: armour-adjacent structure and high-strength jigs and moulds
A typical example is a machined wing rib: a 100 mm 7050-T7451 plate is ultrasonically inspected, nested and saw-cut into blanks, then high-speed machined to a pocketed part with webs a few millimetres thick, shot peened and anodised before assembly.
7050 plate compared with 7075, 7055 and 2024
| Property | 7050-T7451 | 7075-T7351 | 7075-T651 | 7055-T7751 | 2024-T351 |
|---|---|---|---|---|---|
| Typical tensile strength | 524 MPa | 505 MPa | 570 MPa | About 640 MPa | 470 MPa |
| Typical yield strength | 469 MPa | 435 MPa | 505 MPa | About 610 MPa | 325 MPa |
| Thick-plate strength retention | Very good | Poor–fair | Poor–fair | Good | Fair |
| Stress-corrosion resistance | Good–very good | Very good | Poor | Good | Fair |
| Fracture toughness | Good | Moderate | Moderate | Moderate | Good |
| Typical role | Thick machined structure | Fittings, legacy parts | Thin plate, tooling | Upper wing skins | Lower wing, fuselage skin |
7050-T7451 is the best general choice for thick, machined airframe parts. 7055 or 7150 are chosen for compression-dominated upper wing structure where higher strength pays off, and 2024 or 2324 for tension-dominated, damage-tolerant lower wing skins.
How to order 7050 aerospace plate
- SpecifyAlloy and temper, thickness and blank sizes, quantity and the governing specification with its revision (AMS 4050, AMS 4201 or ASTM B209, plus any customer specification).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests (ultrasonic class, conductivity, fracture toughness) and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, straightness or flatness and surface condition; tests named on the order are carried out or arranged with an independent laboratory.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry, tensile results and conductivity where specified, traceable to the cast and lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases or on pallets, with interleaving where surfaces are critical, shipped by sea or air to your port or door.
References and standards
- SAE AMS 4050 – Aluminum Alloy Plate, 7050-T7451
- SAE AMS 4201 – Aluminum Alloy Plate, 7050-T7651
- ASTM B209 – Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
- ASTM B594 – Standard Practice for Ultrasonic Inspection of Aluminum-Alloy Wrought Products
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- ASM Handbook, Vol. 2 – Properties and Selection: Nonferrous Alloys and Special-Purpose Materials
7050 aerospace aluminium (aluminum) plate: FAQ
What does T7451 mean on 7050 plate?
The plate has been solution heat-treated, stretched to relieve quench stresses (the 51) and overaged (the T74) to balance strength against stress-corrosion resistance. It is the standard temper for thick 7050 plate.
Is 7050 plate stronger than 7075 plate?
In thin plate, 7075-T651 is slightly stronger. In thick plate, and against the corrosion-resistant 7075-T7351 temper, 7050-T7451 is stronger and tougher because it is much less quench sensitive.
Which specification covers 7050-T7451 plate?
AMS 4050. AMS 4201 covers T7651 plate and ASTM B209 covers sheet and plate in general. Aircraft manufacturers often add their own specifications on top.
Can 7050 plate be welded?
Not by conventional arc welding. It is joined by fasteners, rivets or bonding. Friction stir welding is used in some structures after qualification.
How much does a 7050 plate weigh?
About 2.83 kg per m² per millimetre of thickness. A 1525 × 3660 × 50.8 mm plate weighs about 802 kg.
Do you cut 7050 plate to size?
Yes. Plate can be saw-cut into blanks to your nesting, with ultrasonic inspection and full certification, and shipped worldwide in export cases.
Need 7050-T7451 plate?
Send thickness, blank sizes, specification and quantity. Our team will reply with availability, certification and a delivered price.
