T3510
Solution heat-treated, stretched for stress relief and not straightened afterwards. Lowest residual stress; dimensional tolerances are slightly wider.
Aerospace extruded sections
2024 Aerospace Aluminium Extrusions and Profiles
2024 extrusions are the traditional choice for fatigue-loaded stringers, frames, spar caps and floor beams in aircraft, combining high strength with a slow crack growth rate. They are normally supplied in the stretched T3510 or T3511 temper, or artificially aged to T8511 for higher yield strength. Metline supplies 2024 angles, tees, channels, Z and J sections, bar and tube to ASTM B221 and AMS specifications, with full mill certification, to customers worldwide.
- Alloy
- 2024 (Al-Cu-Mg)
- Tempers
- O, T3510, T3511, T8511
- Shapes
- Angle, tee, channel, Z, bar, tube
- Standards
- ASTM B221 · AMS-QQ-A-200/3
Why 2024 is used for aircraft extrusions
Most of the extruded length in a conventional metal airframe is in thin open sections: stringers that stiffen the skin, frame chords, floor beams and seat tracks. These parts see millions of load cycles, so fatigue crack growth often governs their design rather than static strength.
2024 answers that requirement well. In the naturally aged T3-type tempers it combines a tensile strength of around 450 – 480 MPa with fracture toughness and crack growth resistance that 7075 cannot match. That is why lower wing stringers and fuselage stringers in many transport aircraft have historically been 2024, while upper wing members loaded mainly in compression use 7xxx alloys.
The alloy is harder to extrude than 6xxx grades. It needs slower press speeds, careful billet temperature control and a separate solution heat treatment and quench, so sections are generally simpler and thicker than architectural profiles. For complex hollow shapes, designers often switch to 6xxx or 7xxx alloys or machine from bar.
2024 chemical composition (wt %)
Composition follows the Aluminum Association registration used by ASTM B221 and the AMS extrusion specifications. A European variant, 2024A, tightens the impurity limits for better toughness; confirm with us if your drawing calls it up.
| Element | Minimum | Maximum |
|---|---|---|
| Silicon (Si) | — | 0.50 |
| Iron (Fe) | — | 0.50 |
| Copper (Cu) | 3.8 | 4.9 |
| Manganese (Mn) | 0.30 | 0.9 |
| Magnesium (Mg) | 1.2 | 1.8 |
| Chromium (Cr) | — | 0.10 |
| Zinc (Zn) | — | 0.25 |
| Titanium (Ti) | — | 0.15 |
| Others, each / total | — | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Mechanical properties of 2024 extrusions
Unlike sheet, the specified minimum strength of 2024-T3511 extrusions rises with section thickness, because thicker sections develop a stronger extrusion texture. The table summarises the pattern; the exact figures for your thickness band are given in ASTM B221 or the AMS specification and on the certificate.
| Temper / thickness | Tensile strength | Yield strength (0.2 %) | Elongation |
|---|---|---|---|
| O (annealed), maximum | ≤ 240 MPa | ≤ 130 MPa | 12 % min |
| T3510 / T3511, thin sections (min.) | about 395 MPa | about 290 MPa | about 12 % |
| T3510 / T3511, thick sections (min.) | about 450 – 485 MPa | about 315 – 360 MPa | about 10 % |
| T8510 / T8511 (min.) | about 440 MPa | about 385 MPa | about 4 – 5 % |
Approximate specified minimums summarised from ASTM B221; use the governing specification for design. Transverse properties are lower than longitudinal values, particularly in thick sections.
Physical properties
- Density
- 2.78 g/cm³
- Modulus of elasticity
- 73 GPa
- Thermal conductivity (T3)
- About 121 W/m·K
- Electrical conductivity (T3)
- About 30 % IACS
- Thermal expansion
- 23.2 µm/m·°C (20 – 100 °C)
- Melting range
- 502 – 638 °C
Choosing a temper for 2024 extrusions
T3511
As T3510, with minor straightening allowed after stretching. The most common temper for 2024 stringers and bar.
T8510 / T8511
Stretched and then artificially aged. Higher yield strength and better resistance to stress corrosion and creep at moderately raised temperatures, at the cost of ductility and some toughness.
O
Annealed for forming. Parts are bent or stretch-formed, then solution treated and aged by the user.
T42
Solution treated by the user from O or F and naturally aged. Properties are slightly below T3.
T6 / T62
Occasionally specified for rings and machined parts heat treated by the user; confirm against your drawing.
Standards and designations
| System | Designation / document |
|---|---|
| ASTM | B221 (extruded bar, rod, wire, profiles and tube); B241 for seamless pipe and tube |
| Federal / AMS | AMS-QQ-A-200/3 (2024 extrusions) |
| SAE AMS | AMS 4152, AMS 4164 and AMS 4165 cover 2024 extrusions in T3-family tempers; check the current revision for exact scope |
| UNS | A92024 |
| European | EN AW-2024 (AlCu4Mg1); EN 755 for extrusions |
| German Werkstoff | 3.1355 |
| French (former) | AU4G1 |
Sizes and tolerances
Typical supply range
- Section size
- Small angles and tees up to profiles fitting a circle of roughly 300 mm, depending on shape
- Wall thickness
- From about 1.5 mm for simple open shapes
- Length
- Mill lengths, fixed lengths or cut pieces
- Tolerances
- ANSI H35.2 / ASTM B221 for standard orders; EN 755-9 for European orders; closer tolerances by agreement
- Surface
- Mill finish; anodising or conversion coating can be arranged
- Inspection
- Dimensional check, straightness and twist; ultrasonic inspection where the specification requires it
Twist and straightness tolerances are particularly important for long stringers that will be riveted to curved skins. If your assembly jig is unforgiving, state tighter limits on the order rather than relying on the default tables.
Machining, forming and joining
Machining
T3511 and T8511 machine well with carbide tooling and give small, broken chips. Stretched tempers minimise distortion when stringer flanges are milled.
Forming
Joggling and stretch forming of stringers are normally done in O or freshly quenched condition, followed by ageing.
Joining
Riveting and bolting are standard. Fusion welding is not recommended for structural joints.
Corrosion protection
Anodise (chromic, sulphuric or boric-sulphuric) or conversion coat, then prime. Seal faying surfaces against moisture.
Typical aerospace uses
- Fuselage and lower wing stringers where fatigue crack growth governs
- Frame chords, floor beams and cargo floor supports
- Seat tracks and interior structural sections
- Machined fittings from extruded bar
- Hydraulic and structural tube
- Missile and UAV airframe longerons
A typical example is a fuselage stringer: a thin Z or hat section in 2024-T3511, riveted to 2024-T3 skin so that crack growth behaviour is matched across the joint.
How to order 2024 extrusions
- SpecifySection drawing or standard shape and size, temper (e.g. 2024-T3511), length, quantity and governing specification, including any ultrasonic class.
- 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.
- ProcessSections are cut to length, inspected for dimensions, straightness and twist, and protected for transport.
- 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
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- AMS-QQ-A-200/3 – Aluminum Alloy 2024, Bar, Rod, Shapes, Tube and Wire, Extruded
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook Vol. 2 – Properties and Selection: Nonferrous Alloys
2024 aerospace aluminium (aluminum) extrusions: FAQ
What is the difference between 2024-T3510 and T3511?
Both are solution treated, stretched and naturally aged. T3511 allows minor straightening after stretching to meet straightness tolerances; T3510 does not, so it has slightly lower residual stress.
Why choose 2024 over 7075 for stringers?
2024 has better fracture toughness and slower fatigue crack growth. 7075 is stronger, so it suits members loaded mainly in compression, such as upper wing stringers.
Can 2024 extrusions be anodised?
Yes. Chromic, sulphuric and boric-sulphuric anodising are all used. The finish is less bright than on 6xxx alloys because of the copper content.
Are custom 2024 profiles possible?
Yes, subject to an extrudability review. 2024 needs simpler shapes and thicker walls than 6xxx alloys, so send the drawing early.
What certification is supplied?
An EN 10204 3.1 mill certificate with chemistry and mechanical results for each lot, plus inspection reports required by the specification.
Need 2024 aerospace extrusions?
Send your section, temper, lengths and specification. We will confirm supply and certification.
