Aluminum 2618A-O (Annealed)
Temper
AA 2618A · EN AlCu2Mg1.5Ni
Softest condition, used only for intermediate working or straightening before re-solution treatment.
Values for the O condition
Other 2618A tempers and conditions
2618A is listed in 10 conditions; see the grade overview at 2618A.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Softest condition, used only for intermediate working or straightening before re-solution treatment. | 130 | 240 | 18 | 65 HB | 44 % IACS |
As fabricated | Intermediate supply condition for parts that will be solution treated and aged after machining or further forging. | 190 | 300 | 14 | 85 HB | 42 % IACS |
Solution heat treated and naturally aged | Rarely stocked; only used as a transient condition when forming or straightening must follow solution treatment. | 240 | 380 | 16 | 95 HB | 34 % IACS |
Solution heat treated and overaged (stabilized) | Overaged for maximum dimensional and property stability in long-term service above 200 °C, trading ~10 % strength. | 330 | 400 | 11 | 105 HB | 42 % IACS |
T6 variant, underaged | Milder quench used on complex forgings and pistons to limit distortion and quench cracking, at a small strength penalty. | 370 | 440 | 10 | 115 HB | 39 % IACS |
T6, stress relieved by stretching, minor straightening | Standard temper for extruded bar and profiles that need straightness plus low residual stress for symmetric machining. | 370 | 435 | 8 | 115 HB | 39 % IACS |
Solution heat treated and artificially aged | Standard peak-aged condition for forged pistons, impellers and small forgings where no stress-relief stretch is applied. | 372 | 440 | 9 | 115 HB | 39 % IACS |
T6, stress relieved by stretching | Choose for machined plate and rolled bar where low residual stress and dimensional stability during machining are critical. | 378 | 440 | 8 | 118 HB | 39 % IACS |
T851Default T8, stress relieved by stretching | Most commonly stocked condition for 2618A plate and rolled/forged bar — peak strength with low residual stress and best machining stability. | 380 | 440 | 8 | 118 HB | 39 % IACS |
Solution treated, cold compressed for stress relief, artificially aged | Specified for hand and die forgings (compressor impellers, engine rings) where stress relief by stretching is impossible. | 390 | 455 | 8 | 122 HB | 39 % IACS |
What is 2618A-O?
2618A-O is 2618A in the O temper — softest condition, used only for intermediate working or straightening before re-solution treatment. 2618A-O has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 73% of aluminum grades. Elongation at break is 18% and the elastic modulus is 74 GPa (10.7 Msi). 2618A-O has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 70% of aluminum grades. It melts at 502°C (936 °F). T851 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 36 MPa·√m (32.8 ksi·√in), better than 93% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Ductile — tolerates forming and impact — 18%, better than 86% of aluminum grades
- High electrical conductivity — 44 % IACS, better than 85% of aluminum grades
- Conducts heat well — 160 W/m·K (92.4 BTU/hr·ft·°F), better than 76% of aluminum grades
Limitations
- High embodied carbon — 14 kg CO₂/kg, worse than 95% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Needs corrosion protection — 36/100, worse than 81% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
2618A-O properties
Typical room-temperature values for 2618A-O; 21 are specific to this condition. Other listed values are 2618A reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
2618A-O has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 70% of aluminum grades. It melts at 502°C (936 °F).
Mechanical15
2618A-O has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 73% of aluminum grades. Elongation at break is 18% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
2618A-O is rated for continuous service to 200°C (392 °F). It conducts heat at 160 W/m·K (92.4 BTU/hr·ft·°F), better than 76% of aluminum grades. Thermal expansion is 22.3 µm/m·K (12.4 µin/in·°F).
Electrical3
2618A-O conducts electricity at 44 % IACS, better than 85% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (36/100), worse than 81% of aluminum grades.
Sustainability4
Producing a kilogram of 2618A-O takes about 210 MJ of energy and emits 14 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 12%.
Manufacturability7
2618A-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability poor (20/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2618A-O
Is 2618A easy to machine?
Machines well in T6/T851 with sharp carbide or PCD tooling and flood coolant, but the hard Al₉FeNi particles cause measurable flank wear — expect shorter tool life than 6061/7075.
Can 2618A be welded?
Not considered fusion weldable for structural use (hot-cracking and loss of temper); joining is by fasteners, friction welding or friction stir with post-weld heat treatment.
Can 2618A be formed, bent or molded?
A forging/extrusion alloy — hot work at roughly 400–450 °C; cold forming in the T tempers is limited to minor straightening and stretching.
What surface finishes work on 2618A?
Hard anodise (Type III) is the standard surface for pistons and engine hardware; decorative anodising is mottled dark grey, so painting/priming or chromate conversion is used for corrosion protection.
2618A chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Si | 0.15 – 0.25 | 0.2 |
| Feforms Al₉FeNi with Ni — key to high-temperature strength | 0.9 – 1.4 | 1.1 |
| Cu | 1.8 – 2.7 | 2.3 |
| Mn | ≤ 0.25 | — |
| Mg | 1.2 – 1.8 | 1.5 |
| Ni | 0.8 – 1.4 | 1.1 |
| Zn | ≤ 0.15 | — |
| TiTi+Zr ≤ 0.25 | ≤ 0.2 | 0.07 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
2618A-O — frequently asked
What is 2618A-O used for?
2618A-O is typically used for jet engine components, forged pistons and high-temperature airframe parts. In short: best hot-strength 2000-series alloy; 200 °C forged engine grade; 2618 to European limits.
What is the yield strength of 2618A-O?
2618A-O has a typical yield strength of 130 MPa (18.9 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 73% of aluminum grades. Strength varies by condition: see the 10 listed tempers.
Is 2618A-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Machines well in T6/T851 with sharp carbide or PCD tooling and flood coolant, but the hard Al₉FeNi particles cause measurable flank wear — expect shorter tool life than 6061/7075.
Can 2618A-O be welded?
Not readily — weldability is rated poor (20/100). Not considered fusion weldable for structural use (hot-cracking and loss of temper); joining is by fasteners, friction welding or friction stir with post-weld heat treatment.
What surface finishes work on 2618A-O?
Hard anodise (Type III) is the standard surface for pistons and engine hardware; decorative anodising is mottled dark grey, so painting/priming or chromate conversion is used for corrosion protection.
Can 2618A-O be formed, bent or molded?
A forging/extrusion alloy — hot work at roughly 400–450 °C; cold forming in the T tempers is limited to minor straightening and stretching.
What is the maximum service temperature of 2618A-O?
2618A-O is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 2618A-T851 and 2618A-O?
T851 is the default condition — most commonly stocked condition for 2618A plate and rolled/forged bar — peak strength with low residual stress and best machining stability. O: softest condition, used only for intermediate working or straightening before re-solution treatment. Yield strength is 380 MPa in T851 versus 130 MPa in O.
Sources
- EN 573-3 Aluminium and aluminium alloys — chemical composition of wrought products — CEN (2019)
- EN 586-2 Aluminium and aluminium alloys — Forgings, mechanical properties — CEN (1994)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- MMPDS-17 (2618 alloy allowables and typicals) — Battelle/FAA (2022)
- AMS 4132 — Aluminum Alloy Forgings 2618, Solution and Precipitation Heat Treated — SAE International (2019)
- High-temperature aluminium forging stock 2618A datasheet — Constellium / Otto Fuchs (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.