T851
Solution treated, stretched 1.5 – 3 % and artificially aged. The standard plate temper for machined aerospace parts: full strength with low residual stress.
Heat-resistant plate
2618 / 2618A Aerospace Aluminium Sheet & Plate
2618A sheet and plate is the heat-resistant aluminium chosen for skins, panels and machined parts that run at 120 – 250 °C, from supersonic airframes to engine nacelles and pistons cut from plate. Metline supplies 2618 and 2618A sheet and plate in T851, T651, T6 and O tempers to European and US aerospace specifications, cut to size and shipped worldwide.
- Alloy
- 2618A / 2618
- Tempers
- T851, T651, T6, O
- Specifications
- DTD 5070 · AIR 9048 · EN aero series
- Service limit
- Up to ~250 °C
Where 2618A plate fits in aerospace
2618A sheet was developed in the UK as RR58 and became famous as the skin and structural material of Concorde, whose surface reached roughly 100 – 125 °C during Mach 2 cruise. No ordinary airframe aluminium could hold its properties for tens of thousands of hours at that temperature without losing strength or creeping.
The secret is in the chemistry: about 1 % iron and 1 % nickel form heat-stable intermetallic particles, while copper and magnesium provide age-hardening. The result is a plate that keeps more of its strength after long exposure at temperature than 2024, 7075 or even 2014, and resists creep under sustained load.
Today 2618A plate is used less for skins and more for machined parts: engine-mount brackets, nacelle fittings, compressor housings, heat-shield supports, and blanks for pistons and impellers where forging is not justified. Stretched T851 or T651 plate stays flat when heavily machined, which matters for large parts with deep pockets.
2618 and 2618A composition (wt %)
| Element | 2618 (AA / ASTM) | 2618A (EN AW-2618A) | Role |
|---|---|---|---|
| Copper (Cu) | 1.9 – 2.7 | 1.8 – 2.7 | Precipitation strengthening with Mg |
| Magnesium (Mg) | 1.3 – 1.8 | 1.2 – 1.8 | Forms the S-phase (Al2CuMg) with copper |
| Iron (Fe) | 0.9 – 1.3 | 0.9 – 1.4 | With Ni forms heat-stable Al9FeNi particles |
| Nickel (Ni) | 0.9 – 1.2 | 0.8 – 1.4 | Elevated-temperature and creep strength |
| Silicon (Si) | 0.10 – 0.25 | 0.15 – 0.25 | Controlled addition |
| Titanium (Ti) | 0.04 – 0.10 | 0.20 max (Ti + Zr 0.25 max) | Grain refiner |
| Manganese (Mn) | — | 0.25 max | Impurity |
| Zinc (Zn) | 0.10 max | 0.15 max | Impurity |
| Others each / total | 0.05 / 0.15 | 0.05 / 0.15 | |
| Aluminium | Remainder | Remainder |
Mechanical and physical properties
| Temper | Tensile strength | Yield strength | Elongation | Basis |
|---|---|---|---|---|
| T851 / T651 plate | ≈ 420 – 440 MPa | ≈ 350 – 410 MPa | ≈ 4 – 8 % | Typical, thickness-dependent |
| T6 sheet | ≈ 420 – 440 MPa | ≈ 350 – 370 MPa | ≈ 8 – 10 % | Typical |
| O (annealed) | ≈ 180 – 220 MPa | — | ≈ 15 % | Typical, for forming |
Specified minimums depend on thickness and direction and are given in the ordered specification; the certificate reports actual results. Short-transverse properties in thick plate are lower.
Retained strength at temperature is what justifies 2618A. Typical data for the closely related T61 temper:
| Test temperature | Tensile strength | Yield strength | Elongation |
|---|---|---|---|
| 24 °C | 440 MPa | 370 MPa | 10 % |
| 100 °C | 420 MPa | 350 MPa | 10 % |
| 150 °C | 345 MPa | 305 MPa | 14 % |
| 205 °C | 220 MPa | 180 MPa | 24 % |
| 260 °C | 90 MPa | 62 MPa | 50 % |
Typical values for 2618-T61 after 10,000 hours at the test temperature (ASM data). They show strength retention, not design minimums.
Physical properties (T61)
- Density
- 2.76 g/cm³ (0.0999 lb/in³)
- Melting range
- about 549 – 638 °C
- Modulus of elasticity
- about 74.5 GPa (10,800 ksi)
- Thermal conductivity
- about 145 – 150 W/m·K
- Coefficient of thermal expansion
- about 22.3 µm/m·°C (20 – 100 °C)
- Electrical conductivity
- about 37 % IACS
2618A plate tempers and when to use them
T651
Equivalent stretched-and-aged condition under different specification naming; machines with minimal distortion.
T6
Solution treated and aged without stretching. Normal for sheet and thin plate where residual stress is low.
T351
Stretched and naturally aged. Sometimes supplied for parts that the user will age after forming or machining.
T62
Heat treated by the user from O or F material, for parts formed in the soft condition first.
O
Annealed for forming. Strength is developed by full heat treatment after forming.
Specifications for 2618A sheet and plate
| Specification | Scope |
|---|---|
| DTD 5070 | UK aerospace specification for 2618A sheet and plate (RR58 family) |
| AIR 9048 (e.g. 9048.640) | French aerospace specification for 2618A (AU2GN) products |
| EN 2123 and related EN aerospace series | European aerospace-series documents quoted for 2618A products; confirm scope and revision |
| EN AW-2618A / Werkstoff 3.1924 | European composition designation (EN 573-3) |
| UNS A92618 | US designation for 2618 |
Because several of these documents are legacy or customer-controlled, always state the exact specification and revision on your enquiry; we confirm which can be certified before quoting.
Sizes and processing
Supply range
- Sheet
- about 1 – 6 mm, T6 or O
- Plate
- about 6 – 150 mm in T851 / T651; thicker sections as forged plate or blocks
- Widths
- up to about 2,000 mm depending on thickness
- Lengths
- mill lengths or cut-to-size blanks
- Processing
- saw cutting, waterjet profiling, ultrasonic inspection on request
Availability of 2618A plate is narrower than common aerospace grades; giving flexible sizes helps.
Plate weighs about 2.76 kg per square metre for every millimetre of thickness. A 1,000 × 2,000 × 25 mm plate weighs roughly 138 kg. Use the plate weight calculator for other sizes.
Machining, forming and joining
- Machining: very good in T851; use sharp carbide tools and flood coolant. Stretched plate resists distortion during deep pocketing.
- Forming: form sheet in O or freshly quenched condition, then age. Fully aged plate has limited bend capability.
- Welding: not recommended for structural joints; the alloy is crack-sensitive. Use mechanical fastening.
- Surface protection: anodise or conversion coat and prime; bare plate has moderate corrosion resistance.
- Creep design: use long-time elevated-temperature data for the expected service hours, not short-time tensile values.
Applications of 2618A sheet and plate
- Supersonic and high-speed airframe skins and structure exposed to aerodynamic heating
- Engine mounts, nacelle fittings and brackets near hot zones
- Compressor and gearbox housings machined from plate
- Piston and impeller blanks cut from thick plate for prototypes and short runs
- Heat-shield supports and ducting brackets
- Motorsport components such as brake and suspension parts near heat sources
References and standards
- EN 573-3 – Chemical composition and form of wrought products
- EN 485-2 – Aluminium sheet, strip and plate: mechanical properties
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook, Vol. 2 – Properties of Wrought Aluminum Alloys: 2618
2618A aluminium (aluminum) plate: FAQ
What is 2618A plate used for?
Machined parts and panels that operate at elevated temperatures, such as engine mounts, nacelle fittings, housings and supersonic airframe structure. It was the main structural alloy of Concorde.
Are 2618 and 2618A the same alloy?
They are close variants. 2618 is the US registration and 2618A the European one; 2618A allows slightly wider iron, nickel and titanium ranges. Mechanical properties are similar, and many programmes accept either, but the specification on your drawing decides which is certified.
Which temper should I order for machined parts?
T851 (or T651), which is stretched to relieve quench stresses and artificially aged. It gives full strength and keeps the plate stable during machining.
Is 2618A plate weldable?
Not for structural joints. Like most high-strength 2xxx alloys it is prone to hot cracking; parts are bolted or riveted.
How does 2618A compare with 2024 plate?
2024 is slightly stronger at room temperature and easier to find, but 2618A keeps more strength and resists creep above about 120 °C, so it is chosen for hot service.
Need heat-resistant 2618A plate?
Send the specification, temper, sizes and quantity. Our team will confirm availability and a delivered price.
