Aluminum 2024 · temper
Aluminum 2024-O
Properties of the O condition, compared with the other 2024 tempers.
Softest, most formable condition — pick it for severe forming/deep drawing, then solution treat and age to T4/T6.
What is 2024-O?
2024-O is 2024 in the O temper — softest, most formable condition — pick it for severe forming/deep drawing, then solution treat and age to T4/T6. 2024-O has a yield strength of 75 MPa (10.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 91% of aluminum grades. Elongation at break is 20% and the elastic modulus is 73.1 GPa (10.6 Msi). 2024-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). T3 is the default condition FabDigit quotes; O 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
- Forms and bends easily — 82/100, better than 91% 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
Limitations
- Low strength — 75 MPa (10.9 ksi), worse than 91% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
2024-O properties
Typical room-temperature values for 2024-O — 15 properties are specific to this condition; the rest are grade-level values shared by every 2024 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
2024-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).
Mechanical14
2024-O has a yield strength of 75 MPa (10.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 91% of aluminum grades. Elongation at break is 20% and the elastic modulus is 73.1 GPa (10.6 Msi).
Thermal6
2024-O is rated for continuous service to 200°C (392 °F). It conducts heat at 193 W/m·K (111.5 BTU/hr·ft·°F), better than 89% of aluminum grades. Thermal expansion is 22.9 µm/m·K (12.7 µin/in·°F).
Electrical3
2024-O conducts electricity at 50 % IACS, better than 90% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of 2024-O takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 10%.
Manufacturability8
2024-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability poor (20/100); formability very good (82/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 2024 tempers and conditions
2024 is also supplied in 17 other conditions. The full side-by-side table is on the 2024 overview.
- T3DefaultThe standard aerospace sheet condition: best combination of strength, fatigue life and damage tolerance; most widely stocked.345 MPa yield · 120 HB
- T861Maximum-strength 2024 sheet temper; very low ductility, so it is only used for flat or lightly formed strength-critical parts.490 MPa yield · 135 HB
- T8Generic T8 condition of 2024: cold work before ageing maximises yield strength (~450 MPa) and gives the best SCC/exfoliation behaviour of the alloy, with low ductility.450 MPa yield · 128 HB
- T81High-yield sheet temper with much better intergranular-corrosion and SCC behaviour than T3; used on skins and supersonic structure.450 MPa yield · 128 HB
- T851Stress-relieved, artificially aged plate/bar: highest yield strength with low machining distortion and improved SCC resistance versus T351.448 MPa yield · 128 HB
- T6Peak-aged condition mainly for bar, forgings and machined parts needing high yield strength; lower toughness and worse corrosion behaviour than T3/T4.400 MPa yield · 125 HB
- T651Artificially aged (T6) 2024 plate stretched ~1.5–3 % after quench for low residual stress; higher yield and better dimensional stability than T351 but lower ductility and toughness.395 MPa yield · 125 HB
- T361Higher-strength cold-worked sheet variant for strength-critical skins; lower ductility and formability than T3.395 MPa yield · 130 HB
- T3511Same as T3510 but with limited straightening allowed — the usual purchase condition for 2024 aerospace extrusions.330 MPa yield · 118 HB
- T4Choose for bar, rod, extrusions and parts formed after solution treatment, where moderate forming and high strength are both needed.325 MPa yield · 120 HB
- T351The standard tooling/aerospace plate condition — low residual stress means far less distortion when machining pockets and ribs.325 MPa yield · 120 HB
- OSoftest, most formable condition — pick it for severe forming/deep drawing, then solution treat and age to T4/T6.75 MPa yield · 47 HB
Working with 2024-O
Is 2024 easy to machine?
Excellent chip formation in T3/T351/T851 — high speeds, sharp positive-rake carbide tools and flood coolant give good finishes; annealed material is gummy.
Can 2024 be welded?
Not suitable for fusion (arc) welding due to hot cracking; join by riveting, bolting, adhesive bonding, resistance spot welding or friction stir welding.
Can 2024 be formed, bent or molded?
Form in O or freshly solution-treated (T4-fresh, often refrigerated) condition; T3/T851 tolerate only large-radius bends and will crack in tight bends.
What surface finishes work on 2024?
Chromic-acid or hard anodize plus primer is normal practice; expect darker, less uniform anodize colour than 6xxx, and use Alclad or conversion coating (Alodine) where corrosion exposure is expected.
2024 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 | ≤ 0.5 | 0.15 |
| Fe | ≤ 0.5 | 0.2 |
| Cuprincipal strengthening addition | 3.8 – 4.9 | 4.4 |
| Mn | 0.3 – 0.9 | 0.6 |
| Mg | 1.2 – 1.8 | 1.5 |
| Cr | ≤ 0.1 | 0.02 |
| Zn | ≤ 0.25 | 0.05 |
| Ti | ≤ 0.15 | 0.03 |
| Other (each)each | ≤ 0.05 | — |
| Other (total)total | ≤ 0.15 | — |
| Al | balance | — |
2024-O — frequently asked
What is 2024-O used for?
2024-O is typically used for aircraft skins and fuselage panels, wing and fuselage structural members, aerospace fittings and brackets, high-strength rivets and fasteners, tooling and jig plate and machined structural components. In short: high fatigue resistance; aerospace.
What is the yield strength of 2024-O?
2024-O has a typical yield strength of 75 MPa (10.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 91% of aluminum grades. Strength varies by condition: see the 18 listed tempers.
Is 2024-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Excellent chip formation in T3/T351/T851 — high speeds, sharp positive-rake carbide tools and flood coolant give good finishes; annealed material is gummy.
Can 2024-O be welded?
Not readily — weldability is rated poor (20/100). Not suitable for fusion (arc) welding due to hot cracking; join by riveting, bolting, adhesive bonding, resistance spot welding or friction stir welding.
What surface finishes work on 2024-O?
Chromic-acid or hard anodize plus primer is normal practice; expect darker, less uniform anodize colour than 6xxx, and use Alclad or conversion coating (Alodine) where corrosion exposure is expected.
Can 2024-O be formed, bent or molded?
Form in O or freshly solution-treated (T4-fresh, often refrigerated) condition; T3/T851 tolerate only large-radius bends and will crack in tight bends.
What is the maximum service temperature of 2024-O?
2024-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 2024-T3 and 2024-O?
T3 is the default condition — the standard aerospace sheet condition: best combination of strength, fatigue life and damage tolerance; most widely stocked. O: softest, most formable condition — pick it for severe forming/deep drawing, then solution treat and age to T4/T6. Yield strength is 345 MPa in T3 versus 75 MPa in O.
Can FabDigit make parts in 2024-O?
Yes — 2024-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
- ASTM B209 / B211 / B221 (Al sheet, plate, bar, extrusions) — ASTM International (2021)
- International Alloy Designations and Chemical Composition Limits (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- MMPDS-17 Metallic Materials Properties Development and Standardization — Battelle/FAA (2022)
- GB/T 3190 / GB/T 3880 (2A12, LY12 ) — SAC (2020)
- EN 573-3 / EN 485-2 (EN AW-2024) — CEN (2019)
- Constellium / Kaiser 2024 aerospace plate & sheet data — Constellium; Kaiser Aluminum (2023)
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.