Machining
Machines well in T851, with low distortion thanks to stretching. Balance roughing from both sides on deep pockets.
Aerospace thick plate
2124 Aerospace Grade Aluminium Plate
2124 is a high-purity version of 2024 made specifically for thick aerospace plate. Lower iron and silicon give better fracture toughness and short-transverse ductility in heavy sections, so 2124-T851 plate is used for machined bulkheads, wing attach fittings and other thick, damage-tolerant parts. Metline supplies 2124-T851 and T351 plate to AMS 4101 and ASTM B209, cut to size and fully certified, to customers worldwide.
- Alloy
- 2124 (high-purity Al-Cu-Mg)
- Tempers
- T851, T351
- Thickness
- About 25 – 152 mm (AMS 4101)
- Standards
- AMS 4101 · ASTM B209
What is 2124 and why does it exist?
When 2024 is rolled into plate thicker than about 25 mm, coarse iron- and silicon-rich particles become starting points for cracks, especially in the short-transverse (through-thickness) direction. 2124 was developed to solve this.
The alloy keeps the copper, magnesium and manganese of 2024 but caps silicon at 0.20 % and iron at 0.30 %. Fewer constituent particles mean higher fracture toughness and better through-thickness ductility, while tensile strength is essentially unchanged. In the T851 temper, which is stretched and artificially aged, the plate also has good resistance to stress-corrosion cracking and holds its strength better at moderately raised temperatures than naturally aged tempers.
The result is a plate grade for heavy machined parts: a 100 mm plate may be machined down to a thin-webbed bulkhead with 90 % of the material removed. Stretching keeps residual stress low, so the part does not distort during machining.
2124 chemical composition (wt %)
| Element | 2124 min. | 2124 max. | 2024 max. (for comparison) |
|---|---|---|---|
| Silicon (Si) | — | 0.20 | 0.50 |
| Iron (Fe) | — | 0.30 | 0.50 |
| Copper (Cu) | 3.8 | 4.9 | 3.8 – 4.9 |
| Manganese (Mn) | 0.30 | 0.9 | 0.30 – 0.9 |
| Magnesium (Mg) | 1.2 | 1.8 | 1.2 – 1.8 |
| Chromium (Cr) | — | 0.10 | 0.10 |
| Zinc (Zn) | — | 0.25 | 0.25 |
| Titanium (Ti) | — | 0.15 | 0.15 |
| Others, each / total | — | 0.05 / 0.15 | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Mechanical and physical properties
Typical 2124-T851 values are about 480 MPa tensile strength and 440 MPa yield strength with 6 – 9 % elongation in the longitudinal direction. AMS 4101 sets minimum values by thickness band and test direction, and also guarantees minimum plane-strain fracture toughness (KIc), which is the main reason to buy 2124 instead of 2024.
| Temper | Condition | Typical tensile | Typical yield | Main benefit |
|---|---|---|---|---|
| T851 | Solution treated, stretched, artificially aged | about 480 MPa | about 440 MPa | High yield, SCC resistance, thermal stability |
| T351 | Solution treated, stretched, naturally aged | about 470 MPa | about 325 MPa | Higher toughness and crack-growth resistance |
Typical values compiled from producer and ASM data. Minimums fall as thickness increases and are lowest in the short-transverse direction; use AMS 4101 or MMPDS for design.
Physical properties
- Density
- 2.78 g/cm³
- Modulus of elasticity
- About 73 GPa
- Thermal conductivity (T851)
- About 150 W/m·K
- Electrical conductivity (T851)
- About 38 % IACS
- Thermal expansion
- 22.9 µm/m·°C (20 – 100 °C)
- Melting range
- About 500 – 640 °C
Standards and equivalents
| System | Designation / document |
|---|---|
| SAE AMS | AMS 4101 – 2124-T851 plate, about 25.4 – 152.4 mm |
| ASTM / ASME | ASTM B209 (sheet and plate) |
| Federal (former) | AMS-QQ-A-250/29 |
| UNS | A92124 |
| European | EN AW-2124 (AlCu4Mg1(A)); EN 485 plate |
Sizes, cutting and inspection
Supply range
- Thickness
- About 25 – 152 mm under AMS 4101; other gauges by agreement
- Plate size
- Mill plate or saw-cut blocks to your machining envelope
- Ultrasonic inspection
- To AMS-STD-2154 or ASTM B594, class as specified (commonly class A or AA for rotating or critical parts)
- Tests
- Tensile in L, LT and ST directions, fracture toughness and conductivity as the specification requires
- Certification
- EN 10204 3.1 mill certificate with chemistry, mechanical and toughness results
For thick plate, the cut position matters. If your part has a highly stressed region, ask for blocks cut so that region lies away from the plate mid-thickness, where properties are lowest.
Machining, joining and protection
Welding
2124 is not fusion welded for structure; it is crack-prone and loses strength. Assemblies are bolted or riveted.
Corrosion
Like 2024, it needs protection: anodise or conversion coat and prime. It is not a seawater-resistant alloy.
Temperature
T851 retains strength better than 7xxx tempers at around 120 – 150 °C, useful near engines and air systems.
Typical uses
- Machined fuselage bulkheads and frames in fighter and transport aircraft
- Wing attach fittings, spar chords and lugs
- Engine mounts and nacelle structure in warm zones
- Space and defence structures requiring guaranteed toughness
| Property | 2124-T851 | 2024-T851 | 7050-T7451 | 7075-T7351 |
|---|---|---|---|---|
| Typical yield | about 440 MPa | about 450 MPa | about 470 MPa | about 435 MPa |
| Thick-plate toughness | Good | Fair | Very good | Good |
| Elevated-temperature strength | Good | Good | Fair | Fair |
| SCC resistance | Good | Good | Very good | Very good |
How to order 2124 plate
- SpecifyTemper (T851 or T351), thickness, plate or block size, quantity, AMS 4101 revision, ultrasonic class and any toughness requirements.
- Confirm the specificationWe check the order against the governing AMS, ASTM or EN document, confirm tempers, sizes, tolerances and any customer flow-down clauses, and quote on EXW, FOB, CIF or DAP terms.
- ProcessPlate is saw cut, marked for grain direction and traceability, ultrasonically inspected where required, and protected.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing heat or lot number, chemical analysis and mechanical test results, plus any ultrasonic or other inspection reports called for on the order.
- Pack and shipMaterial is protected against moisture and handling damage, packed in seaworthy cases or on pallets, marked for traceability and shipped by sea or air.
References and standards
- SAE AMS 4101 – Aluminum Alloy Plate, 2124-T851
- ASTM B209 – Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
- AMS-STD-2154 – Inspection, Ultrasonic, Wrought Metals
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
2124 aerospace aluminium (aluminum) plate: FAQ
What is the difference between 2124 and 2024?
2124 has lower iron (0.30 % max.) and silicon (0.20 % max.). Strength is similar, but thick 2124 plate has higher fracture toughness and better short-transverse ductility.
What thickness range does AMS 4101 cover?
Plate from about 25.4 mm (1 in) to 152.4 mm (6 in) in the T851 temper.
Can 2124 plate be welded?
Not for structural joints. Like 2024 it is prone to hot cracking and loses strength in the weld zone; parts are bolted or riveted.
Is 2124 good in seawater?
No. It is a copper-bearing alloy that needs anodising, conversion coating and paint. For marine exposure, 5xxx alloys are far better.
Do you supply ultrasonic-tested 2124 plate?
Yes, to AMS-STD-2154 or ASTM B594 at the class specified on the order, with the report included in the documentation.
Need 2124 aerospace plate?
Send thickness, size, temper and specification. We will reply with availability, inspection and certification.
