7050-T74 (formerly T736)
Solution heat-treated, quenched and overaged. The standard condition for closed-die forgings where the forged shape is close to the final part and residual stress is not a major concern.
Aerospace · die and hand forgings
7050 Aerospace Aluminium Forgings (T74 / T7452)
7050 forgings combine high strength, good fracture toughness and strong resistance to stress-corrosion cracking in thick sections, which makes them a first choice for bulkheads, wing and landing-gear fittings and engine mounts. Die forgings are ordered in T74 (AMS 4107) or T7452 (AMS 4333), and hand forgings in T7452 (AMS 4108). Metline supplies 7050 die forgings, hand forgings, rings and forged blocks with full certification to customers worldwide.
- Alloy
- 7050 (Al-Zn-Cu-Mg-Zr)
- Tempers
- T74 (formerly T736), T7452
- Forms
- Die, hand and ring forgings
- Standards
- AMS 4107 · 4108 · 4333 · ASTM B247
Why aircraft designers choose 7050 forgings
Forging works the metal into the shape of the part, so the grain flows around corners and lugs instead of being cut through as it is when a part is machined from plate. That grain flow improves fatigue life and short-transverse properties, which is exactly where heavily loaded aerospace fittings tend to fail.
7050 suits forging particularly well. Its zirconium addition keeps the grain structure fine and makes the alloy far less quench sensitive than 7075, so the centre of a thick forging still reaches high strength. Overageing to T74 then gives strong resistance to stress-corrosion cracking. This combination replaced 7075-T73 forgings on many airframes, since 7050-T74 offers similar corrosion resistance with noticeably higher strength.
The T74 temper was originally designated T736, and some older drawings and certificates still use that name. Forgings that are compressed after quenching to relieve residual stress carry the T7452 temper, which is preferred for hand forgings and large die forgings that will be machined heavily.
7050 chemical composition (wt %)
Forgings use the same registered 7050 composition as plate and extrusions. Some published tables list germanium or strontium for 7050, or give copper and zinc ranges that belong to other alloys; the correct limits are below.
| 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 % |
Mechanical properties of 7050 forgings
Forging properties depend on section thickness, test direction and where the specimen is taken, so specifications set separate minimums for longitudinal, long-transverse and short-transverse directions and for each thickness band. The values below are approximate typical figures for moderate sections; use the specification minimums for design.
| Temper | Tensile strength (typical) | Yield strength (typical) | Elongation | Typical product |
|---|---|---|---|---|
| T74 die forgings (AMS 4107) | About 495 – 510 MPa / 72 – 74 ksi | About 430 – 455 MPa / 62 – 66 ksi | About 10 – 13 % | Closed-die fittings and frames |
| T7452 hand forgings (AMS 4108) | About 490 – 505 MPa | About 420 – 440 MPa | About 9 – 12 % | Open-die blocks and bar |
| T7452 die forgings (AMS 4333) | About 495 – 510 MPa | About 425 – 445 MPa | About 9 – 12 % | Large die forgings for heavy machining |
Short-transverse values are lower than longitudinal values. Hardness of T74 forgings is typically around 140 HB.
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
T74 versus T7452 forgings
7050-T7452
Solution heat-treated, then compressed by about 1 – 5 % permanent set to relieve quench stresses before overageing. Used for hand forgings and large die forgings that will be extensively machined, because they distort much less.
Forging stock (F)
Bar or billet supplied as fabricated for the forging shop, with heat treatment carried out after forging.
7050 forging specifications
| Specification | Scope |
|---|---|
| AMS 4107 | 7050-T74 die forgings up to 6 in (152 mm) thick, and forging stock |
| AMS 4108 | 7050-T7452 hand forgings up to 8 in (203 mm) thick, and forging stock |
| AMS 4333 | 7050-T7452 die forgings |
| ASTM B247 | Die forgings, hand forgings and rolled ring forgings (general) |
| AMS 2772 / AMS 2770 | Heat treatment of aluminium-alloy raw materials and parts |
| AMS-STD-2154 / ASTM B594 | Ultrasonic inspection |
| UNS / EN | A97050 / EN AW-7050 (AlZn6CuMgZr), EN 586 for forgings |
Defence programmes may call military detail specifications, and aircraft manufacturers add their own forging specifications covering grain flow, first-article approval and frozen process routes. Please quote every applicable document on the enquiry.
Forging types and size range
Closed-die forgings
Near-net-shape parts produced in matched dies: fittings, frames, bulkhead sections and landing-gear components. Economic for repeat parts where tooling cost can be spread over the programme.
Hand (open-die) forgings
Blocks, bars and simple shapes worked between flat or simple dies. Ideal for prototypes, low volumes and large machined parts.
Rolled rings
Seamless rings for engine mounts, launch-vehicle joints and rotating structures.
Forged discs and shafts
Upset discs and stepped shafts for hubs and actuator parts.
Size limits depend on press capacity and the heat-treatment and quench equipment available for the part. Hand forgings up to 203 mm thick are covered by AMS 4108; larger sections and very large die forgings are quoted case by case. Send the machined-part envelope and we will propose the forging type and stock size.
Inspection and certification of 7050 forgings
- Chemical analysis per cast and tensile testing per lot in the directions the specification requires
- Electrical conductivity and hardness checks to confirm the overaged temper
- Ultrasonic inspection to AMS-STD-2154 at the class ordered
- Grain-flow macro-etch and first-article inspection on new die forgings where specified
- Fluorescent penetrant inspection of machined or forged surfaces when called up
- EN 10204 3.1 certificate with full traceability to cast, heat-treatment lot and forging number
Machining and finishing 7050 forgings
7050 forgings machine cleanly with sharp carbide tools, high speeds and flood coolant. T7452 forgings hold their shape better than T74 when large amounts of material are removed. Balance roughing between faces and allow a finishing pass after stress has redistributed.
Fusion welding is not recommended. Parts are fastened, bushed and sealed into the structure. Surface protection is normally chromic, sulphuric or boric-sulphuric anodising, or conversion coating plus primer. Fatigue-critical lugs and fillets are often shot peened, and interference-fit bushings or cold expansion of holes are used to extend fatigue life.
Typical 7050 forging applications
- Fuselage: main frames, pressure-bulkhead parts and door-surround fittings
- Wing: wing-to-body fittings, spar fittings and flap-track and slat-track parts
- Landing gear: trunnion fittings, side braces, wheel and brake parts in aluminium designs
- Engines and nacelles: engine mounts, pylon fittings and thrust-reverser parts
- Helicopters: rotor hubs, swashplate parts and transmission mounts
- Defence: structural forgings for armoured vehicles and missile airframes
7050 forgings compared with 7075 and 2014
| Property | 7050-T74 | 7075-T73 | 7075-T6 | 2014-T6 |
|---|---|---|---|---|
| Typical tensile strength | About 500 MPa | About 470 – 500 MPa | About 560 MPa | About 480 MPa |
| Stress-corrosion resistance | Very good | Excellent | Poor | Fair |
| Thick-section strength | Very good | Fair | Fair | Fair |
| Fracture toughness | Good | Moderate | Moderate | Moderate |
7050-T74 gives most of the corrosion resistance of 7075-T73 with clearly higher strength in thick sections, so it is usually the preferred replacement when a 7075-T73 forging needs upgrading.
How to order 7050 forgings
- SpecifyAlloy and temper, drawing or envelope dimensions, quantity and the governing specification with its revision (AMS 4107, AMS 4108, AMS 4333 or ASTM B247, plus any customer forging 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 4107 – Aluminum Alloy Die Forgings, 7050-T74
- SAE AMS 4108 – Aluminum Alloy Hand Forgings, 7050-T7452
- SAE AMS 4333 – Aluminum Alloy Die Forgings, 7050-T7452
- ASTM B247 – Standard Specification for Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
- 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) forgings: FAQ
What is the difference between 7050-T74 and T736?
They are the same temper. T736 was the original designation and was later renamed T74. Older drawings and certificates may still show T736.
What does the 52 in T7452 mean?
After quenching the forging is compressed by about 1 – 5 % permanent set to relieve residual stress, then overaged. This reduces distortion during machining.
Which specification covers 7050 hand forgings?
AMS 4108 covers 7050-T7452 hand forgings up to 8 in thick. AMS 4107 covers T74 die forgings and AMS 4333 covers T7452 die forgings.
Why use 7050 instead of 7075 for forgings?
7050 keeps high strength in thick sections and has better toughness, while T74 gives stress-corrosion resistance close to 7075-T73. The result is a stronger forging with similar durability.
Can 7050 forgings be welded?
Fusion welding is not recommended because of cracking and strength loss in the weld zone. Forgings are joined mechanically.
Can you supply prototype forgings without die tooling?
Yes. Hand forgings and forged blocks are a practical route for prototypes and small batches; die forgings make sense once volumes justify the tooling.
Need 7050 forgings?
Send the drawing, temper, specification and quantity. Our team will confirm the forging route, certification and a delivered price.
