Aluminum 2224-T39
Temper
AA 2224 · UNS A92224
T39 = 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.
Values for the T39 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 |
|---|---|---|---|---|---|---|
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 |
T39This page 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-T39?
2224-T39 is 2224 in the T39 temper — cold-worked plate temper giving the highest naturally aged yield strength while keeping good toughness for lower wing skins. 2224-T39 has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 490 MPa (71.1 ksi) — stronger than 91% of aluminum grades. Elongation at break is 8% and the elastic modulus is 73 GPa (10.6 Msi). 2224-T39 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; T39 is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 37 MPa·√m (33.7 ksi·√in), better than 94% of aluminum grades
- High strength — 440 MPa (63.8 ksi), better than 91% of aluminum grades
- Easy to machine — 74/100, better than 85% of aluminum grades
Limitations
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Needs corrosion protection — 35/100, worse than 85% of aluminum grades
- Poor heat conductor — 120 W/m·K (69.3 BTU/hr·ft·°F), worse than 80% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
2224-T39 properties
Typical room-temperature values for 2224-T39; 11 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-T39 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-T39 has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 490 MPa (71.1 ksi) — stronger than 91% of aluminum grades. Elongation at break is 8% and the elastic modulus is 73 GPa (10.6 Msi).
Thermal6
2224-T39 is rated for continuous service to 120°C (248 °F). It conducts heat at 120 W/m·K (69.3 BTU/hr·ft·°F), worse than 80% of aluminum grades. Thermal expansion is 22.9 µm/m·K (12.7 µin/in·°F).
Electrical3
2224-T39 conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 85% of aluminum grades.
Sustainability4
Producing a kilogram of 2224-T39 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-T39's machinability is very good (74/100, better than 85% of aluminum grades); weldability poor (20/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2224-T39
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-T39 — frequently asked
What is 2224-T39 used for?
2224-T39 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-T39?
2224-T39 has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 490 MPa (71.1 ksi) — stronger than 91% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 2224-T39 easy to machine?
Yes — machinability is rated very good (74/100, better than 85% 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-T39 be welded?
Not readily — weldability is rated poor (20/100). 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-T39?
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-T39 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-T39?
2224-T39 is rated for continuous use to about 120°C (248 °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.