Closed-die (die) forgings
Metal is pressed between shaped dies to near-final geometry. Best for repeat parts: fittings, brackets, wheels, frames and bulkhead segments. Specified as die forgings in AMS and ASTM B247.
Forgings for aircraft and space
Aerospace Aluminium Forgings
Aerospace forgings are aluminium parts shaped under compression so that the grain follows the part outline, giving better fatigue life, toughness and reliability than plate or bar machined to the same shape. Metline supplies die forgings, hand forgings, rolled rings and forged blanks in 7050, 7075, 7175, 2014, 2219, 2618 and 6061 to AMS, ASTM and EN specifications, for aircraft, launch vehicle and satellite programmes worldwide.
- Forging types
- Die, hand, rolled ring, blanks
- Main alloys
- 7050 · 7075 · 2014 · 2219
- Standards
- AMS · ASTM B247 · EN 586
- Inspection
- UT to AMS-STD-2154
Why aerospace structures use forgings
A forging is not simply a stronger piece of metal. Its advantage is direction: the hot working stretches grains and inclusions along the contours of the part, so cracks have to run across that grain flow rather than along it. In fatigue-critical parts such as wing-to-fuselage fittings, landing-gear components and engine mounts, that difference shows up as longer life and slower crack growth.
Forging also closes internal porosity left from casting, refines the grain and lets the designer place material only where it is needed. A closed-die forging of a bulkhead fitting may need only a fraction of the machining that the same part cut from thick plate would need, which saves both material and machine time on expensive high-strength alloys.
Aluminium forgings dominate in airframes because the 7xxx and 2xxx alloys offer high strength at low density. Where temperatures exceed about 150 °C for long periods, as in engine hot sections or nozzle hardware, designers move to titanium or nickel alloys. Metline focuses on aluminium forgings and forging stock; titanium and steel hot-section parts are outside our range.
Types of aerospace forgings
Open-die (hand) forgings
Blocks, bars and simple shapes worked between flat or simple dies. Used for prototypes, low volumes and large blanks that will be machined. Thick hand forgings are often supplied in stress-relieved tempers such as T7452 or T7352.
Seamless rolled rings
A pierced billet is expanded on a ring mill into rings with circumferential grain flow. Used for fuselage and tank interface rings, engine casings, flanges and launch-vehicle joints.
Precision / near-net forgings
Thin webs and tight draft angles that need little machining. Suitable for high-volume parts once tooling cost is justified.
Forged discs and shafts
Upset discs for wheel, flange and turbine-adjacent parts; drawn-out shafts for actuators and control linkages.
Forging stock
Extruded or cast billet and bar supplied to forge shops, with chemistry and ultrasonic quality controlled for the forging process.
Aluminium forging alloys, tempers and specifications
The table lists the alloys most often forged for aerospace use, with representative SAE AMS material specifications. Revisions change, so always quote the specification and revision from your drawing.
| Alloy | Typical tempers | Representative specifications | Why it is chosen |
|---|---|---|---|
| 7050 | T74, T7452 | AMS 4107 (die), AMS 4108 (hand), AMS-A-22771 | High strength with good toughness and SCC resistance in thick sections; low quench sensitivity |
| 7075 | T6, T73, T7352 | AMS 4126, AMS 4141, AMS-QQ-A-367 | Long-established high-strength alloy; T73 for stress-corrosion resistance |
| 7175 | T74, T7452 | AMS 4149 and related | Higher-purity 7075 variant for better toughness and fatigue |
| 7049 / 7149 | T73, T7352 | AMS-QQ-A-367, AMS-A-22771 | High strength in heavy sections such as landing-gear components |
| 2014 | T6, T652 | AMS 4133, AMS 4134, AMS-QQ-A-367 | High strength, good machinability; wheels and heavy fittings |
| 2219 | T6, T852 | AMS 4143, AMS 4144 | Weldable, good at cryogenic and moderately elevated temperatures; launch-vehicle tank rings |
| 2618 | T61 | AMS 4132 | Retains strength to about 150 – 200 °C; engine-adjacent parts, impellers |
| 6061 | T6, T652 | AMS 4127, ASTM B247 | Weldable, corrosion resistant, economical; secondary structure and ground equipment |
AMS-QQ-A-367 and AMS-A-22771 are general forging specifications that replaced the old federal and military documents; individual AMS numbers give tighter, alloy-specific requirements.
Typical properties of aerospace forging alloys
Values below are typical for forgings of moderate section, drawn from published handbook data. Specified minimums depend on section thickness and test direction (longitudinal, long-transverse, short-transverse) and are lower than these typical values.
| Alloy-temper | Tensile strength | Yield strength | Elongation | Density |
|---|---|---|---|---|
| 7050-T74 | ~510 MPa | ~455 MPa | ~11 % | 2.83 g/cm³ |
| 7075-T6 | ~570 MPa | ~505 MPa | ~11 % | 2.81 g/cm³ |
| 7075-T73 | ~505 MPa | ~435 MPa | ~13 % | 2.81 g/cm³ |
| 7175-T74 | ~525 MPa | ~455 MPa | ~11 % | 2.80 g/cm³ |
| 2014-T6 | ~485 MPa | ~415 MPa | ~13 % | 2.80 g/cm³ |
| 2219-T6 | ~415 MPa | ~290 MPa | ~10 % | 2.84 g/cm³ |
| 2618-T61 | ~440 MPa | ~370 MPa | ~10 % | 2.76 g/cm³ |
| 6061-T6 | ~310 MPa | ~276 MPa | ~12 % | 2.70 g/cm³ |
Short-transverse properties matter most in thick forgings, because that is where stress-corrosion cracks start. This is the main reason why 7050-T74 and 7075-T73 have largely replaced 7075-T6 for primary-structure forgings.
Where aerospace aluminium forgings are used
| System | Typical forged parts | Common alloys |
|---|---|---|
| Wing and fuselage | Wing-root and pylon fittings, frame segments, door surrounds, bulkhead fittings | 7050, 7075, 7175 |
| Landing gear | Support brackets, trunnion fittings, wheel halves, brake housings | 7050, 7049, 2014 |
| Flight controls | Hinge brackets, actuator lugs, bellcranks, control shafts | 7075, 7050, 2024 |
| Engine mounting | Mount brackets, nacelle fittings, intake rings | 2618, 7050, 2014 |
| Launch vehicles | Tank Y-rings, dome rings, inter-stage and payload adapter rings | 2219, 2195 (Al-Li), 7050 |
| Satellites | Interface rings, separation-system flanges, structural nodes, antenna mounts | 7075, 2219, 6061 |
| Ground and test equipment | Test-stand flanges, handling fixtures, transport-cradle fittings | 6061, 6082, 7075 |
A typical example: a launch-vehicle propellant tank joins its cylindrical barrel to its dome through a forged 2219 Y-ring. The ring is rolled seamless, heat treated, machined to its Y profile and then friction-stir or fusion welded to the tank, because 2219 keeps good strength and toughness both after welding and at cryogenic temperatures.
Heat treatment, inspection and certification
For aerospace use, how a forging is processed matters as much as the alloy. Specifications control the heat-treatment cycle, quench, stress relief, testing locations and acceptance criteria.
Key controls
- Heat treatment
- Solution treatment, quench and ageing per AMS 2770 (parts) or AMS 2772 (raw material), with furnace uniformity per AMS 2750
- Stress relief
- Compression or stretch stress relief (T7352, T7452, T652) to limit distortion during machining
- Ultrasonic testing
- AMS-STD-2154 (formerly MIL-STD-2154), class AAA to B depending on criticality
- Mechanical tests
- Tensile in L, LT and ST directions from prolongations or sacrificial parts; hardness and conductivity checks for 7xxx
- Grain flow
- Macro-etch of a sectioned first article to confirm flow lines follow the contour
- First article
- First Article Inspection to AS9102 where the customer requires it
- Certification
- EN 10204 3.1 mill certificate with chemistry, heat-treatment lot, test results and traceability
Third-party inspection by an agency named by the customer can be arranged before shipment.
Design and buying advice
- Choose the temper for the environment: T73 or T74 for thick 7xxx parts exposed to sustained tensile stress; T6 only where stress-corrosion is not a risk
- Watch section thickness: strength falls as section increases because the centre cools more slowly during quench. 7050 is far less quench-sensitive than 7075
- Balance die cost against volume: hand forgings or forged blocks suit prototypes and short runs; closed-die tooling pays back on repeat orders
- State test directions: if short-transverse properties matter, say so on the order so test pieces are cut accordingly
- Specify machining allowance: leave enough stock to remove the forged surface layer and the flash line, but not so much that machining cuts through the favourable grain flow
- Ask for the inspection class early: ultrasonic class AA or AAA affects the forging route and cost
Common forging defects and how specifications control them
Most rejections of aerospace aluminium forgings trace back to a handful of known defect types. Knowing them helps buyers write sensible requirements and read inspection reports.
| Defect | Cause | How it is prevented or found |
|---|---|---|
| Laps and folds | Metal folds over itself when die filling is poor or fillet radii are too sharp | Die design with generous radii; fluorescent penetrant inspection of finished surfaces |
| Flow-through and end-grain exposure | Grain flow cut by machining or forced through thin sections | Macro-etch of first articles; machining allowance planned with the die design |
| Coarse grain / recrystallisation | Too little strain in a region followed by solution treatment | Controlled forging temperatures and reductions; grain-size checks on sections |
| Internal voids and inclusions | Unconsolidated porosity or oxide films carried from the billet | Ultrasonically inspected stock; AMS-STD-2154 inspection of the forging |
| Quench cracks and distortion | Severe thermal gradients in complex or thick parts | Polymer or warm-water quench; compression stress relief (T7452, T652) |
| Wrong temper | Ageing cycle errors or furnace non-uniformity | Hardness and electrical conductivity checks; AMS 2750 furnace control |
Electrical conductivity testing is a fast, non-destructive way to confirm that a 7xxx forging has been over-aged to T73 or T74 rather than left in T6. The specifications set conductivity bands for each temper, and readings below the band trigger further testing.
From billet to certified forging
- StockHomogenised cast or extruded billet of certified chemistry, ultrasonically inspected.
- ForgeBillet heated to about 400 – 460 °C and forged in open dies, closed dies or on a ring mill, often in several stages.
- Heat treatSolution treatment, rapid quench (water or polymer) and, for thick parts, mechanical stress relief.
- AgeArtificial ageing to the specified temper, verified by hardness and conductivity.
- TestTensile, ultrasonic, dimensional and macro-etch inspections as required.
- Machine and shipRough or finish machining on request, then protective packing and shipment with certificates.
How to order aerospace forgings
- SpecifyAlloy and temper, drawing or envelope dimensions, ultrasonic class, quantity and the governing specification with its revision (e.g. AMS 4107, AMS-A-22771, ASTM B247).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, straightness and surface condition; tests named on the order are carried out or arranged with a third party.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry and mechanical results, traceable to the cast or lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases, coils on pallets or reels, shipped by sea or air to your port or door.
References and standards
- ASTM B247 – Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
- SAE AMS-A-22771 – Aluminum Alloy Forgings, Heat Treated
- SAE AMS-QQ-A-367 – Aluminum Alloy Forgings
- SAE AMS-STD-2154 – Inspection, Ultrasonic, Wrought Metals, Process for
- EN 586 – Aluminium and aluminium alloys: forgings
- ASM Handbook, Vol. 2 – Properties and Selection: Nonferrous Alloys and Special-Purpose Materials
Aerospace aluminium (aluminum) forgings: frequently asked questions
Why use a forging instead of machining from plate?
Forging aligns grain flow with the part shape, improves short-transverse properties and fatigue life, and reduces the amount of expensive alloy machined away.
Which aluminium alloy is most common for aerospace forgings?
7050-T74 and T7452 for most primary structure today, followed by 7075-T73 and 2014-T6. 2219 is preferred for welded launch-vehicle rings.
What is the difference between die forgings and hand forgings?
Die forgings are pressed between shaped dies to near-final geometry and suit repeat production. Hand forgings are worked between flat or simple dies into blocks or simple shapes and are machined to final form.
What does the "52" in T7452 or T652 mean?
It shows the forging was stress-relieved by compression (typically 1 – 5 % permanent set) after quenching, which reduces distortion when machined.
Which ultrasonic class should I specify?
Class AA or AAA under AMS-STD-2154 for fracture-critical rotating or primary-structure parts; class A or B for less critical parts. Your design authority sets the class.
Do you supply titanium forgings?
No. Metline specialises in aluminium. For hot-section parts above aluminium's temperature range, a titanium or nickel-alloy specialist is the right source.
Planning an aerospace forging?
Send the drawing, alloy, temper and specification. We will confirm the forging route, testing and certification.
