Joints
Use bolted or riveted gussets, machined end fittings or structural adhesive. Avoid fusion welds, which crack and lose strength.
High-strength square hollow section
2024 Aluminium Square Tube
2024 aluminium square tube is a high-strength, heat-treatable hollow section used where a frame member must resist bending, torsion and repeated loading at low weight: aircraft and defence structures, motorsport frames and precision equipment. It is supplied mainly as extruded tube in T3511 to AMS-QQ-A-200/3 and ASTM B221, and as drawn tube in T3. Metline supplies 2024 square tube cut to length and certified, worldwide.
- Alloy
- 2024 (Al-Cu-Mg)
- Tempers
- T3511, T3, T4, O
- Process
- Extruded, drawn
- Standards
- AMS-QQ-A-200/3 · ASTM B221
What is 2024 aluminium square tube?
A square hollow section puts material far from the neutral axis on all four sides, so it is stiff in bending about both axes and strong in torsion. Made in 2024, it adds high strength and fatigue resistance to that geometry.
2024 is a copper-magnesium alloy that is solution heat-treated and naturally aged. Extruded square tube is normally supplied in T3511: after quenching it is stretched by a controlled amount to remove residual stress, with minor straightening allowed, and then aged at room temperature. The stress relief matters because square tube is often slotted, drilled or machined on one face, and unrelieved tube would bow as material is removed.
Square 2024 tube is less common than 6061 or 6063 square tube and is usually specified for a reason: a strut, longeron, seat track, launcher frame or race-car member that sees cyclic loads where 6061-T6 would be too weak or would crack in fatigue. Because 2024 cannot be arc welded reliably, square tube frames in this alloy are assembled with fasteners, rivets, bonded joints or machined end fittings.
2024 chemical composition (wt %)
Registered limits for 2024 (EN AW-2024, AlCu4Mg1). The certificate for each lot reports the actual analysis.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | — | 0.50 | Impurity |
| Iron (Fe) | — | 0.50 | Impurity; lower levels improve toughness |
| Copper (Cu) | 3.8 | 4.9 | Main strengthening element (Al2CuMg precipitates) |
| Manganese (Mn) | 0.30 | 0.9 | Strength and grain control |
| Magnesium (Mg) | 1.2 | 1.8 | Works with copper to raise strength and natural-ageing response |
| Chromium (Cr) | — | 0.10 | Impurity |
| Zinc (Zn) | — | 0.25 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
Mechanical properties of 2024 square tube
For extruded 2024 the specified minimums rise with section thickness, because thicker extrusions are produced with more working and quench efficiently enough in this size range. The thin-wall band below covers most square tube.
| Temper / product | Basis | Tensile strength | Yield strength | Elongation |
|---|---|---|---|---|
| T3511 extruded, wall ≤ 6.3 mm (0.249 in) | Specified minimum (AMS-QQ-A-200/3, ASTM B221) | 393 MPa / 57 ksi | 290 MPa / 42 ksi | 12 % |
| T3511 extruded, heavier walls | Specified minimum | Higher; by section band | Higher; by section band | 10 – 12 % |
| T3 drawn tube | Specified minimum (ASTM B210) | 441 MPa / 64 ksi | 290 MPa / 42 ksi | 10 – 16 % |
| T3 / T4 | Typical | 469 – 483 MPa | 324 – 345 MPa | 18 – 20 % |
| O | Typical | 186 MPa | 76 MPa | 20 % |
Physical properties of 2024 (typical)
- Density
- 2.78 g/cm³ (0.100 lb/in³)
- Modulus of elasticity
- 73.1 GPa (10,600 ksi)
- Shear strength (T3)
- 283 MPa (41 ksi)
- Fatigue strength (T3, 5×10⁸ cycles)
- 138 MPa (20 ksi)
- Thermal conductivity (T3)
- 121 W/m·K
- Electrical conductivity (T3)
- 30 % IACS
- Thermal expansion (20 – 100 °C)
- 23.2 µm/m·°C
- Melting range
- 502 – 638 °C
Sizes, weight and section properties
The table gives mass per metre (density 2.78 g/cm³), second moment of area I and elastic section modulus Z about either axis, calculated for sharp corners. Extruded tube has small corner radii, so real values are slightly lower; use the extruder's drawing for final design.
| Size (mm) | Wall (mm) | Mass (kg/m) | I (cm⁴) | Z (cm³) |
|---|---|---|---|---|
| 20 × 20 | 2 | 0.400 | 0.79 | 0.79 |
| 25 × 25 | 2 | 0.512 | 1.63 | 1.31 |
| 25.4 × 25.4 | 3.18 | 0.786 | 2.37 | 1.87 |
| 30 × 30 | 3 | 0.901 | 3.99 | 2.66 |
| 38.1 × 38.1 | 3.18 | 1.235 | 9.10 | 4.78 |
| 40 × 40 | 3 | 1.234 | 10.20 | 5.10 |
| 50 × 50 | 3 | 1.568 | 20.85 | 8.34 |
| 50 × 50 | 5 | 2.502 | 30.75 | 12.30 |
| 60 × 60 | 4 | 2.491 | 47.07 | 15.69 |
| 76.2 × 76.2 | 6.35 | 4.932 | 145.46 | 38.18 |
| 80 × 80 | 5 | 4.170 | 141.25 | 35.31 |
| 100 × 100 | 6 | 6.272 | 333.59 | 66.72 |
Supply range
- Extruded square tube
- Common sizes from about 20 mm to 100 mm and above, imperial or metric
- Drawn square tube
- Smaller sizes with tighter tolerances and sharper corners, drawn from round
- Rectangular tube
- Also available in 2024 to drawing
- Length
- Mill lengths or cut to size
- Tolerances
- ANSI H35.2 / ASTM B221 standard tolerances, or EN 755-9 for EN orders
Designing with 2024 square tube
Corrosion
Anodise or conversion coat and prime. Seal the tube interior or provide drainage where moisture can collect.
Galvanic contact
Isolate from carbon fibre and stainless steel with sealant, washers or primer.
Machining
T3511 keeps tube straight during slotting and pocketing. Use sharp carbide tools; chips break well.
Local buckling
Thin walls on wide faces can buckle before the material yields. Check width-to-thickness ratio for compression members.
Temperature
Stable to about 120 – 150 °C. For hotter service consider 2219 or 2618.
Specifications and equivalents
| System | Designation | Specification |
|---|---|---|
| SAE AMS | 2024 extrusions | AMS-QQ-A-200/3 (extruded bar, rod, shapes, tube and wire) |
| ASTM | 2024 | ASTM B221 (extruded), B210 (drawn seamless) |
| UNS | A92024 | — |
| European (EN) | EN AW-2024 (AlCu4Mg1) | EN 755-2 and EN 755-9 (extruded profiles and tolerances) |
| German Werkstoff | 3.1355 | — |
| Japan (JIS) | A2024 | JIS H4100 (extruded shapes) |
Where 2024 square tube is used
- Aircraft: seat structures, cargo-system rails, floor support members and equipment racks
- Defence: launcher frames, shelters, vehicle equipment mounts and portable structures
- Motorsport and drones: chassis members, wing supports and airframe booms
- Industrial equipment: high-load machine frames and test rigs where members are bolted
- Precision tooling: fixtures and gantries machined from square section
2024 square tube vs 6061 square tube
| Factor | 6061-T6 square tube | 2024-T3511 square tube |
|---|---|---|
| Typical tensile strength | 310 MPa | 469 – 483 MPa |
| Fatigue strength | About 96 MPa | About 138 MPa |
| Weldability | Good | Poor; bolt or bond |
| Corrosion resistance | Good | Fair; needs protection |
| Availability and cost | Wide, lower cost | Narrower, higher cost |
If a welded frame is needed, 6061 or 7005 tube is the practical alternative. See 6061 square tube and 7005 tube.
How to order 2024 square tube
- SpecifySize and wall, temper (T3511 or T3), specification and revision, lengths, quantity.
- QuoteWe confirm availability, tolerances, inspection and delivery terms (EXW, FOB, CIF or DAP).
- ProcessCutting to length and deburring; machining to drawing on request.
- ShipWrapped and crated with an EN 10204 3.1 certificate and heat-lot traceability.
References and standards
- SAE AMS-QQ-A-200/3 – Aluminum Alloy 2024, Bar, Rod, Shapes, Tube and Wire, Extruded
- ASTM B221 – Extruded Bars, Rods, Wire, Profiles, and Tubes
- EN 755-2 and EN 755-9 – Extruded rod, bar, tube and profiles: properties and tolerances
- ASM International – Properties of Wrought Aluminium Alloys: 2024
2024 aluminium (aluminum) square tube: frequently asked questions
What temper is 2024 square tube supplied in?
Usually T3511 for extruded tube: solution heat-treated, stretched for stress relief, lightly straightened and naturally aged. Drawn square tube is supplied in T3.
How strong is 2024-T3511 square tube?
For walls up to 6.3 mm (0.249 in), specified minimums are about 393 MPa (57 ksi) tensile and 290 MPa (42 ksi) yield with 12 % elongation. Typical values are higher, and thicker sections have higher minimums.
Can 2024 square tube be welded into a frame?
Arc welding is not recommended because 2024 is prone to hot cracking and loses strength near welds. Frames are bolted, riveted or bonded; for welded frames use 6061 or 7005.
How do I protect 2024 square tube from corrosion?
Anodise or apply a conversion coating and primer, seal or drain the inside of the tube, and isolate it from dissimilar metals and carbon fibre.
Is 2024 stronger than 6061 square tube?
Yes. Typical tensile strength is about 470 – 480 MPa against 310 MPa for 6061-T6, and fatigue strength is around 40 % higher.
Need 2024 square tube?
Send the size, temper, specification and quantity. We will reply with availability, certification and a delivered price.
