Aluminum 2224-O (Annealed)
Temper
AA 2224 · UNS A92224
Mill/interim annealed condition for maximum formability before solution treatment; not a service temper.
Values for the O condition
Other 2224 tempers and conditions
2224 is listed in 6 conditions; see the grade overview at 2224.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Mill/interim annealed condition for maximum formability before solution treatment; not a service temper. | 78 | 185 | 20 | 47 HB | 50 % IACS |
T3, stress relieved by stretching | Standard damage-tolerant plate temper for machined wing and fuselage structure where low residual stress matters. | 330 | 470 | 12 | 122 HB | 30 % IACS |
T3511Default Solution treated, stretched, naturally aged, minor straightening… | The workhorse condition for 2224 extruded stringers and spar caps — best combination of strength, toughness and crack-growth resistance. | 425 | 480 | 9 | 132 HB | 30 % IACS |
Solution treated, cold worked, naturally aged | Cold-worked plate temper giving the highest naturally aged yield strength while keeping good toughness for lower wing skins. | 440 | 490 | 8 | 137 HB | 30 % IACS |
T8, stress relieved by stretching | Artificially aged plate temper chosen for higher yield strength, better thermal stability and much improved exfoliation/SCC resistance. | 450 | 480 | 6 | 135 HB | 38 % IACS |
Solution treated, stretched, artificially aged, minor straightening… | Artificially aged extrusion temper for stiffeners needing peak yield strength and elevated-temperature stability rather than maximum toughness. | 455 | 490 | 6 | 137 HB | 38 % IACS |
What is 2224-O?
2224-O is 2224 in the O temper — mill/interim annealed condition for maximum formability before solution treatment; not a service temper. 2224-O has a yield strength of 78 MPa (11.3 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 90% of aluminum grades. Elongation at break is 20% and the elastic modulus is 73 GPa (10.6 Msi). 2224-O has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 502°C (936 °F). T3511 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 40 MPa·√m (36.4 ksi·√in), better than 98% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- High electrical conductivity — 50 % IACS, better than 90% of aluminum grades
- Ductile — tolerates forming and impact — 20%, better than 89% of aluminum grades
- Conducts heat well — 190 W/m·K (109.8 BTU/hr·ft·°F), better than 89% of aluminum grades
Limitations
- Low strength — 78 MPa (11.3 ksi), worse than 90% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
2224-O properties
Typical room-temperature values for 2224-O; 18 are specific to this condition. Other listed values are 2224 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
2224-O has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 502°C (936 °F).
Mechanical12
2224-O has a yield strength of 78 MPa (11.3 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 90% of aluminum grades. Elongation at break is 20% and the elastic modulus is 73 GPa (10.6 Msi).
Thermal6
2224-O is rated for continuous service to 200°C (392 °F). It conducts heat at 190 W/m·K (109.8 BTU/hr·ft·°F), better than 89% of aluminum grades. Thermal expansion is 22.9 µm/m·K (12.7 µin/in·°F).
Electrical3
2224-O conducts electricity at 50 % IACS, better than 90% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 69% of aluminum grades.
Sustainability4
Producing a kilogram of 2224-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 10%.
Manufacturability7
2224-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability poor (25/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2224-O
Is 2224 easy to machine?
Machines very well in T3/T8 tempers with sharp carbide tools, high speed and flood coolant; residual-stress-relieved (T351/T3511) stock is essential for thin machined web parts.
Can 2224 be welded?
Not suitable for fusion arc welding (hot cracking, loss of properties) — join by riveting, bolting, adhesive bonding or friction stir welding.
Can 2224 be formed, bent or molded?
Form in O or freshly quenched W condition; cold forming in T3/T8 tempers is limited and demands generous bend radii.
What surface finishes work on 2224?
Use chromic/sulfuric anodize plus chromate-free primer, or clad/paint systems; bare surfaces need protection because of Cu-driven pitting, and anodic films are non-decorative.
2224 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 |
|---|---|---|
| Cu | 3.8 – 4.4 | 4.1 |
| Mg | 1.2 – 1.8 | 1.5 |
| Mn | 0.3 – 0.9 | 0.6 |
| Siheld low for toughness | ≤ 0.12 | — |
| Feheld low for toughness | ≤ 0.15 | — |
| Cr | ≤ 0.1 | — |
| Zn | ≤ 0.25 | — |
| Ti | ≤ 0.15 | — |
| Others (each)0.15 total | ≤ 0.05 | — |
| Al | balance | — |
2224-O — frequently asked
What is 2224-O used for?
2224-O is typically used for aircraft structural plate, machined fuselage bulkheads, wing ribs and spar webs, floor beams and seat tracks, machined aerospace fittings from thick plate and damage-tolerance-critical airframe structure. In short: higher-toughness 2024 plate; stress-relieved machining stock; riveted, not welded.
What is the yield strength of 2224-O?
2224-O has a typical yield strength of 78 MPa (11.3 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 90% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 2224-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Machines very well in T3/T8 tempers with sharp carbide tools, high speed and flood coolant; residual-stress-relieved (T351/T3511) stock is essential for thin machined web parts.
Can 2224-O be welded?
Not readily — weldability is rated poor (25/100). Not suitable for fusion arc welding (hot cracking, loss of properties) — join by riveting, bolting, adhesive bonding or friction stir welding.
What surface finishes work on 2224-O?
Use chromic/sulfuric anodize plus chromate-free primer, or clad/paint systems; bare surfaces need protection because of Cu-driven pitting, and anodic films are non-decorative.
Can 2224-O be formed, bent or molded?
Form in O or freshly quenched W condition; cold forming in T3/T8 tempers is limited and demands generous bend radii.
What is the maximum service temperature of 2224-O?
2224-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 2224-T3511 and 2224-O?
T3511 is the default condition — the workhorse condition for 2224 extruded stringers and spar caps — best combination of strength, toughness and crack-growth resistance. O: mill/interim annealed condition for maximum formability before solution treatment; not a service temper. Yield strength is 425 MPa in T3511 versus 78 MPa in O.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — Aluminum Association (2018)
- MMPDS-2023, Metallic Materials Properties Development and Standardization — Battelle/FAA (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- AMS-QQ-A-250 / AMS 4000 series aluminum plate and extrusion specifications — SAE International (2020)
- High-toughness 2000-series aerospace plate and extrusion product data — Alcoa / Arconic (2015)
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.