Aluminum 2618 · temper
Aluminum 2618-O
Properties of the O condition, compared with the other 2618 tempers.
Choose for deep forming, straightening or heavy machining before solution treating and ageing.
What is 2618-O?
2618-O is 2618 in the O temper — choose for deep forming, straightening or heavy machining before solution treating and ageing. 2618-O has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 75% of aluminum grades. Elongation at break is 18% and the elastic modulus is 74.5 GPa (10.8 Msi). 2618-O has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 69% of aluminum grades. It melts at 549°C (1,020 °F).
Advantages
- Ductile — tolerates forming and impact — 18%, better than 86% of aluminum grades
- Forms and bends easily — 70/100, better than 83% of aluminum grades
- High electrical conductivity — 41 % IACS, better than 78% of aluminum grades
- Conducts heat well — 160 W/m·K (92.4 BTU/hr·ft·°F), better than 75% of aluminum grades
Limitations
- Needs corrosion protection — 32/100, worse than 94% of aluminum grades
- Difficult to weld — 22/100, worse than 83% of aluminum grades
- Difficult to machine — 40/100, worse than 80% of aluminum grades
- Low strength — 125 MPa (18.1 ksi), worse than 75% of aluminum grades
2618-O properties
Typical room-temperature values for 2618-O — 11 properties are specific to this condition; the rest are grade-level values shared by every 2618 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
2618-O has a density of 2.76 g/cm³ (0.0997 lb/in³), heavier than 69% of aluminum grades. It melts at 549°C (1,020 °F).
Mechanical15
2618-O has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 75% of aluminum grades. Elongation at break is 18% and the elastic modulus is 74.5 GPa (10.8 Msi).
Thermal6
2618-O is rated for continuous service to 150°C (302 °F). It conducts heat at 160 W/m·K (92.4 BTU/hr·ft·°F), better than 75% of aluminum grades. Thermal expansion is 22.3 µm/m·K (12.4 µin/in·°F).
Electrical3
2618-O conducts electricity at 41 % IACS, better than 78% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 94% of aluminum grades.
Sustainability4
Producing a kilogram of 2618-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 75% of aluminum grades. Typical recycled content is 5%.
Manufacturability8
2618-O's machinability is fair (40/100, worse than 80% of aluminum grades); weldability poor (22/100); formability very good (70/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 2618 tempers and conditions
2618 is also supplied in 5 other conditions. The full side-by-side table is on the 2618 overview.
- T651Pick for plate and rolled bar that will be heavily machined — low residual stress means minimal distortion.375 MPa yield · 118 HB
- T61The standard supply condition for 2618 pistons, turbo wheels and elevated-temperature forgings — best balance of hot strength and residual-stress control.372 MPa yield · 115 HB
- T6General peak-aged condition for forgings and bar where no stress-relief stretching is applied.370 MPa yield · 115 HB
- OChoose for deep forming, straightening or heavy machining before solution treating and ageing.125 MPa yield · 65 HB
Working with 2618-O
Is 2618 easy to machine?
Machines cleanly in T6/T61 with sharp PCD or polished carbide, high speed and flood coolant; hard Fe-Ni intermetallics accelerate edge wear compared with 6061.
Can 2618 be welded?
Not recommended for fusion welding (hot cracking, loss of aged strength); join by mechanical fasteners, friction welding or FSW with post-weld ageing where qualified.
Can 2618 be formed, bent or molded?
Hot forge/extrude at 400–450 °C; cold forming only in O temper — T61 material is essentially non-formable and must be machined to shape.
What surface finishes work on 2618?
Hard anodize (Type III) for piston crowns and wear faces gives a dark grey, non-uniform film; chromate/TCP conversion coat plus primer for corrosion protection, and avoid bare seawater exposure.
2618 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 | 0.1 – 0.25 | 0.18 |
| Feforms Al9FeNi dispersoids for creep strength | 0.9 – 1.3 | 1.1 |
| Cu | 1.9 – 2.7 | 2.3 |
| Mg | 1.3 – 1.8 | 1.5 |
| Ni | 0.9 – 1.2 | 1.05 |
| Ti | 0.04 – 0.1 | 0.07 |
| Zn | ≤ 0.1 | — |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
2618-O — frequently asked
What is 2618-O used for?
2618-O is typically used for forged engine pistons, turbocharger compressor wheels, cylinder heads, aero-engine accessory components, high-temperature structural forgings and supersonic aircraft skin panels. In short: concorde alloy; high-temp aerospace.
What is the yield strength of 2618-O?
2618-O has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 75% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 2618-O easy to machine?
Not especially — machinability is rated fair (40/100, worse than 80% of aluminum grades). Machines cleanly in T6/T61 with sharp PCD or polished carbide, high speed and flood coolant; hard Fe-Ni intermetallics accelerate edge wear compared with 6061.
Can 2618-O be welded?
Not readily — weldability is rated poor (22/100). Not recommended for fusion welding (hot cracking, loss of aged strength); join by mechanical fasteners, friction welding or FSW with post-weld ageing where qualified.
What surface finishes work on 2618-O?
Hard anodize (Type III) for piston crowns and wear faces gives a dark grey, non-uniform film; chromate/TCP conversion coat plus primer for corrosion protection, and avoid bare seawater exposure.
Can 2618-O be formed, bent or molded?
Hot forge/extrude at 400–450 °C; cold forming only in O temper — T61 material is essentially non-formable and must be machined to shape.
What is the maximum service temperature of 2618-O?
2618-O is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 2618-O?
Yes — 2618-O is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- MMPDS (Metallic Materials Properties Development and Standardization) — FAA/Battelle (2023)
- AMS 4132 — Aluminum Alloy Forgings 2618, Solution and Precipitation Heat Treated — SAE International (2019)
- EN 573-3 / EN 586 — Aluminium and aluminium alloys, chemical composition and forgings — CEN (2019)
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.