Aluminum 7449-O (Annealed)
Temper
AA 7449 · UNS A97449 · EN AW-7449
Mill/intermediate condition for heavy forming or re-heat-treat; not a service temper.
Values for the O condition
Other 7449 tempers and conditions
7449 is listed in 8 conditions; see the grade overview at 7449.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Mill/intermediate condition for heavy forming or re-heat-treat; not a service temper. | 110 | 235 | 16 | 65 HB | 45 % IACS |
Forging, solution treated, cold-compression stress relieved, overaged | Die/hand forgings where through-thickness SCC resistance and low residual stress matter. | 545 | 590 | 8 | 172 HB | 39 % IACS |
T7951Default Solution treated, stretched, retrogression/near-peak overaged plate | The standard supply condition for 7449 thick plate: near-peak strength with improved SCC/exfoliation over T6. | 570 | 620 | 10 | 180 HB | 38 % IACS |
T76, stress relieved by stretching | Best compromise of high strength with good exfoliation resistance for wing skin plate. | 605 | 640 | 9 | 188 HB | 35 % IACS |
T6, stress relieved by stretching | Peak-aged plate with low residual stress for machined parts where SCC exposure is limited. | 615 | 655 | 8 | 193 HB | 31 % IACS |
Extrusion, solution treated, stretched, T79 overaged | High-strength stringer extrusions for upper wing panels. | 615 | 645 | 9 | 188 HB | 37 % IACS |
Solution heat treated and artificially aged | Maximum strength for thin, non-stress-corrosion-critical parts; poorest SCC/exfoliation resistance. | 620 | 660 | 8 | 195 HB | 31 % IACS |
Extrusion, solution treated, stretched, T76 overaged | Stringer/spar extrusions needing high strength with exfoliation resistance. | 620 | 650 | 9 | 190 HB | 35 % IACS |
What is 7449-O?
7449-O is 7449 in the O temper — mill/intermediate condition for heavy forming or re-heat-treat; not a service temper. 7449-O has a yield strength of 110 MPa (16 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 16% and the elastic modulus is 70 GPa (10.2 Msi). 7449-O has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 475°C (887 °F). T7951 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 45 MPa·√m (41 ksi·√in), better than 100% of aluminum grades
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Conducts heat well — 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades
- High electrical conductivity — 45 % IACS, better than 86% of aluminum grades
- Ductile — tolerates forming and impact — 16%, better than 84% of aluminum grades
Limitations
- Difficult to weld — 22/100, worse than 83% of aluminum grades
- Low strength — 110 MPa (16 ksi), worse than 81% of aluminum grades
- Needs corrosion protection — 40/100, worse than 75% of aluminum grades
7449-O properties
Typical room-temperature values for 7449-O; 21 are specific to this condition. Other listed values are 7449 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7449-O has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 475°C (887 °F).
Mechanical13
7449-O has a yield strength of 110 MPa (16 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 16% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7449-O is rated for continuous service to 200°C (392 °F). It conducts heat at 180 W/m·K (104 BTU/hr·ft·°F), better than 86% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7449-O conducts electricity at 45 % IACS, better than 86% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 75% of aluminum grades.
Sustainability4
Producing a kilogram of 7449-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 12%.
Manufacturability7
7449-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability poor (22/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7449-O
Is 7449 easy to machine?
Machines well in T7x with sharp polished-flute carbide tools, high speed and flood or MQL coolant; plan symmetric stock removal and stress-relieved (T-x51/x52) material to control distortion in thin-web parts.
Can 7449 be welded?
Not suitable for fusion welding (hot cracking, severe HAZ softening and SCC); join by fasteners, bonding, or friction stir welding with qualified parameters.
Can 7449 be formed, bent or molded?
Form in W or freshly quenched condition or hot; aged T6/T7x plate has low ductility and large minimum bend radii — cold forming is limited to gentle contours and stretch-forming of skins.
What surface finishes work on 7449?
Chromic/sulphuric or tartaric-sulphuric anodize plus chromate-free primer is standard aerospace practice; hard anodize is possible but coating is dark and slightly brittle, and shot peening is often used on machined SCC-critical surfaces.
7449 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 |
|---|---|---|
| Siimpurity limit | ≤ 0.12 | 0.06 |
| Feimpurity limit | ≤ 0.15 | 0.08 |
| Cu | 1.4 – 2.1 | 1.8 |
| Mn | ≤ 0.2 | 0.05 |
| Mg | 1.8 – 2.7 | 2.2 |
| Cr | ≤ 0.05 | 0.02 |
| Znprincipal strengthening addition | 7.5 – 8.7 | 8.1 |
| Tigrain refiner | ≤ 0.25 | 0.03 |
| Zrdispersoid former (reported with Ti as Ti+Zr limit in some registrations) | ≤ 0.25 | 0.12 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
7449-O — frequently asked
What is 7449-O used for?
7449-O is typically used for aircraft wing plate, forged wing structure, high-strength structural components, machined wing ribs and spars, airframe forgings and fittings and thick plate for machined aerospace structure. In short: european 7055-class plate; good machinability for 7000 series; available in SCC-resistant T7x.
What is the yield strength of 7449-O?
7449-O has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 81% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 7449-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Machines well in T7x with sharp polished-flute carbide tools, high speed and flood or MQL coolant; plan symmetric stock removal and stress-relieved (T-x51/x52) material to control distortion in thin-web parts.
Can 7449-O be welded?
Not readily — weldability is rated poor (22/100). Not suitable for fusion welding (hot cracking, severe HAZ softening and SCC); join by fasteners, bonding, or friction stir welding with qualified parameters.
What surface finishes work on 7449-O?
Chromic/sulphuric or tartaric-sulphuric anodize plus chromate-free primer is standard aerospace practice; hard anodize is possible but coating is dark and slightly brittle, and shot peening is often used on machined SCC-critical surfaces.
Can 7449-O be formed, bent or molded?
Form in W or freshly quenched condition or hot; aged T6/T7x plate has low ductility and large minimum bend radii — cold forming is limited to gentle contours and stretch-forming of skins.
What is the maximum service temperature of 7449-O?
7449-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 7449-T7951 and 7449-O?
T7951 is the default condition — the standard supply condition for 7449 thick plate: near-peak strength with improved SCC/exfoliation over T6. O: mill/intermediate condition for heavy forming or re-heat-treat; not a service temper. Yield strength is 570 MPa in T7951 versus 110 MPa in O.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- EN 485-2 Aluminium and aluminium alloys — Sheet, strip and plate: mechanical properties — CEN (2016)
- EN 755-2 Aluminium and aluminium alloys — Extruded rod/bar, tube and profiles: mechanical properties — CEN (2016)
- High-strength 7000-series aerospace plate and extrusion product data (7449/7040/7050) — Constellium (formerly Alcan/Pechiney) (2021)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys — ASM International (1990)
- MMPDS-17 typical property practice for 7000-series wrought products — Battelle/FAA (2022)
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.