T351
Solution treated, stretched 1 – 3 % and naturally aged. The standard cold-finished bar temper for machined parts.
Aerospace rod & bar · 2xxx series
2024 (2A12) Aerospace Aluminium Rod & Bar
2024 rod and bar is the fatigue-resistant, high-strength aluminium machining stock of the aircraft industry: about 470 MPa typical tensile strength in T351, with good toughness and very good machinability. It is turned and milled into fittings, shafts, pins and fasteners. Metline supplies 2024 and its close equivalent 2A12 as cold-finished and extruded round, square, hexagon and flat bar, certified to AMS, ASTM and EN standards, worldwide.
- Alloy
- 2024 / 2A12
- Tempers
- T3, T4, T351, T3511, T851
- Diameter
- about 5 – 420 mm
- Standards
- AMS 4120 · AMS 4152 · ASTM B211
Why 2024 bar is used in aerospace
2024 combines copper with a relatively high magnesium content (1.2 – 1.8 %). Natural ageing after solution treatment produces fine copper-magnesium precipitates that give high strength together with good toughness and fatigue resistance. That balance, rather than peak strength, is why 2024 is chosen for many airframe parts.
Bar is produced in two ways. Cold-finished bar (rolled or drawn) is held to close diameter tolerances and is usually supplied in T351 or T4, with T851 for parts that need higher yield strength or better stress-corrosion resistance. Extruded bar covers larger diameters and rectangular sections and is supplied in T3511 (stretched and straightened) or T3510.
Compared with 7075, 2024 is less strong but more damage tolerant: cracks grow more slowly under cyclic loads. Compared with 2014, it has lower yield strength but better fatigue performance. In practice, 2024-T351 bar is a common default for machined fittings, while 7075-T7351 is used where higher strength and stress-corrosion resistance are both needed.
2024 and 2A12 composition (wt %)
| Element | 2024 (AA / ASTM, EN AW-2024) | 2A12 (GB, close equivalent) | Role |
|---|---|---|---|
| Copper (Cu) | 3.8 – 4.9 | 3.8 – 4.9 | Main strengthening element |
| Magnesium (Mg) | 1.2 – 1.8 | 1.2 – 1.8 | With Cu forms the Al2CuMg (S-phase) precipitates |
| Manganese (Mn) | 0.30 – 0.9 | 0.30 – 0.9 | Grain control, toughness |
| Silicon (Si) | 0.50 max | 0.50 max | Impurity |
| Iron (Fe) | 0.50 max | 0.50 max | Impurity; low Fe improves toughness |
| Chromium (Cr) | 0.10 max | — | Impurity |
| Nickel (Ni) | — | 0.10 max | Impurity |
| Zinc (Zn) | 0.25 max | 0.30 max | Impurity |
| Titanium (Ti) | 0.15 max | 0.15 max | Grain refiner |
| Others, each / total | 0.05 / 0.15 | 0.05 / 0.10 | |
| Aluminium (Al) | Remainder | Remainder | About 90.7 – 94.7 % |
Some product listings swap the manganese and magnesium ranges. In 2024, magnesium is 1.2 – 1.8 % and manganese 0.30 – 0.9 %.
Mechanical and physical properties
Under ASTM B211, cold-finished 2024-T4 / T351 bar carries minimums of about 425 MPa (62 ksi) tensile and 290 MPa (42 ksi) yield in common diameters, and T851 about 455 MPa (66 ksi) tensile and 400 MPa (58 ksi) yield. Extruded T3511 bar follows ASTM B221 minimums that rise with section size.
| Temper | Tensile strength | Yield strength (0.2 %) | Elongation | Brinell hardness | Shear strength |
|---|---|---|---|---|---|
| O | 186 MPa / 27 ksi | 76 MPa / 11 ksi | 20 % | 47 HB | 125 MPa |
| T3 | 483 MPa / 70 ksi | 345 MPa / 50 ksi | 18 % | 120 HB | 283 MPa |
| T4, T351 | 469 MPa / 68 ksi | 324 MPa / 47 ksi | 19 – 20 % | 120 HB | 283 MPa |
| T6 | 476 MPa / 69 ksi | 393 MPa / 57 ksi | 10 % | 125 HB | 283 MPa |
| T81, T851 | 483 MPa / 70 ksi | 448 MPa / 65 ksi | 6 % | 128 HB | 296 MPa |
Physical properties of 2024
- Density
- 2.78 g/cm³ (0.100 lb/in³)
- Modulus of elasticity
- about 73 GPa (10.6 Msi)
- Poisson's ratio
- 0.33
- Fatigue strength (5×10⁸ cycles, T3/T4)
- about 138 MPa
- Melting range
- about 502 – 638 °C
- Thermal conductivity
- about 121 W/m·K (T3/T4); about 151 W/m·K (T8)
- Electrical conductivity
- about 30 % IACS (T3/T4); about 38 % IACS (T8)
- Coefficient of thermal expansion
- about 23.2 µm/m·°C (20 – 100 °C)
Common bar tempers
T4
Solution treated and naturally aged without stretching. Used for smaller bar and wire.
T3
Solution treated, cold worked and naturally aged; drawn bar with good strength and close tolerances.
T3511 / T3510
Extruded bar stretched after quenching, with or without minor straightening.
T851
T351 bar artificially aged. Higher yield strength, lower elongation and much better stress-corrosion resistance; also better for service around 100 – 150 °C.
O
Annealed stock for forging or forming before heat treatment.
Specifications and equivalents
Bar and rod specifications
- AMS 4120
- 2024-T351 rolled or cold-finished bar, rod and wire
- AMS-QQ-A-225/6
- 2024 bar, rod and wire (former QQ-A-225/6)
- AMS 4152
- 2024-T3 / T3511 extruded bar, rod, shapes and tube
- AMS-QQ-A-200/3
- 2024 extrusions (former QQ-A-200/3)
- ASTM B211 / ASTM B221
- Cold-finished and extruded bar and rod
- EN 754-2 / EN 755-2
- Drawn and extruded EN AW-2024 bar
- GB/T 3191
- Extruded 2A12 bar (Chinese standard)
| System | Designation |
|---|---|
| Aluminum Association / UNS | 2024 / A92024 |
| European (EN) | EN AW-2024 / AlCu4Mg1 |
| German Werkstoff / DIN | 3.1355 / AlCuMg2 |
| ISO | AlCu4Mg1 |
| France (old NF) | AU4G1 |
| Japan (JIS) | A2024 |
| China (GB) | 2A12 (close equivalent) |
Sizes and weights
Supply range
- Round bar
- about 5 – 420 mm diameter; imperial 1/4 – 16 in
- Square bar
- about 6 – 150 mm
- Flat / rectangular bar
- about 3 – 100 mm thick, widths to about 300 mm
- Hexagon bar
- about 6 – 75 mm across flats
- Length
- 3 m, 3.66 m and 6 m standard; cut pieces to order
2024 round bar weighs about 0.00218 × d² kg per metre (d in mm, density 2.78 g/cm³). See the bar weight calculator for other shapes.
| Diameter (mm) | kg per metre | 3 m bar (kg) | 6 m bar (kg) |
|---|---|---|---|
| 6 | 0.079 | 0.24 | 0.47 |
| 10 | 0.218 | 0.66 | 1.31 |
| 12 | 0.314 | 0.94 | 1.89 |
| 16 | 0.559 | 1.68 | 3.35 |
| 20 | 0.873 | 2.62 | 5.24 |
| 25 | 1.36 | 4.09 | 8.19 |
| 30 | 1.97 | 5.90 | 11.79 |
| 40 | 3.49 | 10.48 | 20.96 |
| 50 | 5.46 | 16.38 | 32.75 |
| 60 | 7.86 | 23.58 | 47.16 |
| 80 | 13.97 | 41.92 | 83.84 |
| 100 | 21.83 | 65.50 | 131.00 |
| 150 | 49.13 | 147.38 | 294.76 |
| 200 | 87.34 | 262.01 | 524.02 |
| 250 | 136.46 | 409.39 | 818.78 |
| 300 | 196.51 | 589.52 | 1179.04 |
| 400 | 349.35 | 1048.04 | 2096.07 |
Tolerances and inspection
Cold-finished bar follows ANSI H35.2 (ASTM/AMS) or EN 754-3 tolerances; extruded bar follows ANSI H35.2 or EN 755-3. Aerospace bar above about 12 mm is often ultrasonically inspected to AMS-STD-2154 or ASTM B594, class as specified.
- Tensile tests per lot and conductivity checks
- Ultrasonic inspection on request
- Diameter, straightness and surface checks
- EN 10204 3.1 certificate with full traceability
Machining and finishing
Machining
Good to very good in T351 and T851; chips are less brittle than 2011 but break well with chip-breaker inserts.
Joining
Mechanical fastening; 2024 is not fusion-welded in structure.
Finishing
Sulphuric or hard anodising, conversion coatings and primers. Protect all machined faces.
Stress corrosion
T3/T351 are susceptible in the short-transverse direction of thick bar; T851 is much more resistant.
Applications
- Machined airframe fittings, lugs and brackets
- Shafts, pins, bolts and special fasteners
- Actuator and landing-gear components
- Missile and defence hardware
- Hydraulic valve parts and precision machined components
- Motorsport and high-performance machinery parts
2024 bar compared with 2014, 2017A and 7075
| Property | 2024-T351 | 2014-T651 | 2017A-T451 | 7075-T651 |
|---|---|---|---|---|
| Typical tensile strength | ~469 MPa | ~483 MPa | ~425 MPa | ~572 MPa |
| Typical yield strength | ~324 MPa | ~414 MPa | ~275 MPa | ~503 MPa |
| Fatigue performance | Very good | Fair | Good | Fair |
| Machinability | Good | Very good | Very good | Very good |
| Relative cost | Moderate | Moderate | Lower | Higher |
How to order
- SpecifyAlloy (2024 or 2A12), temper, shape and size, length and quantity.
- Name the standardAMS 4120, AMS 4152, ASTM B211, ASTM B221, EN 754/755 or your customer specification.
- QuoteWe confirm availability, tolerance, test scope, certification and delivery terms (EXW, FOB, CIF or DAP) for your port or site.
- Process and inspectBars are cut, end-marked and checked for size, straightness and surface.
- Document and shipEach lot ships with an EN 10204 3.1 mill test certificate traceable to the heat and lot, plus a packing list. Material is packed in seaworthy wooden cases with moisture protection; third-party inspection can be arranged on request.
References and standards
- SAE AMS 4152 – Aluminum Alloy Extrusions, 2024-T3
- SAE AMS 4120 – Aluminum Alloy Bars, Rods and Wire, 2024-T351
- ASTM B211 – Aluminum and Aluminum-Alloy Rolled or Cold-Finished Bar, Rod and Wire
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
2024 aerospace aluminium (aluminum) bar: FAQ
Is 2A12 the same as 2024?
2A12 is the Chinese GB designation with essentially the same composition. It is a close equivalent, but aerospace orders should state the designation and standard required by the drawing.
What is the difference between 2024-T351 and T851?
T851 is T351 bar that has been artificially aged. It has higher yield strength and much better stress-corrosion resistance, but lower elongation.
Is 2024 or 7075 better for machined fittings?
7075 is stronger; 2024 has better fatigue crack-growth resistance and toughness. The choice depends on whether static strength or damage tolerance governs.
Can 2024 bar be welded?
Not by fusion welding for structural parts. Use mechanical fastening.
What is the largest 2024 round bar available?
Extruded round bar is available up to about 420 mm diameter; larger sections are produced as forgings.
Need 2024 rod or bar?
Send size, temper, specification and quantity, and we will confirm availability and a delivered price.
