Aluminum 7055-T77
Temper
AA 7055 · UNS A97055 · EN AW-7055, AW 7055
T77 = overaged
Generic overaged designation used for forgings and thin product where stretching/compression stress relief is not applied.
Values for the T77 condition
Other 7055 tempers and conditions
7055 is listed in 4 conditions; see the grade overview at 7055.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution heat treated (unstable) | Transient shop condition immediately after solution quenching, used for forming/straightening before artificial overaging; not a delivery temper. | 250 | 400 | 17 | 110 HB | 30 % IACS |
T77This page Overaged | Generic overaged designation used for forgings and thin product where stretching/compression stress relief is not applied. | 610 | 640 | 10 | 185 HB | 37 % IACS |
Solution treated, stress relieved by stretching, overaged | Extruded-product equivalent of T7751 — stringers, spar caps and other extruded compression members. | 621 | 648 | 10 | 188 HB | 37 % IACS |
Solution treated, stress relieved by stretching, overaged | The standard commercial condition for 7055 plate: maximum strength with acceptable exfoliation and SCC resistance for upper wing / compression structure. | 634 | 655 | 11 | 190 HB | 37 % IACS |
What is 7055-T77?
7055-T77 is 7055 in the T77 temper — generic overaged designation used for forgings and thin product where stretching/compression stress relief is not applied. 7055-T77 has a yield strength of 610 MPa (88.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 99% of aluminum grades. Elongation at break is 10% and the elastic modulus is 70.5 GPa (10.2 Msi). 7055-T77 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% of aluminum grades. It melts at 475°C (887 °F).
Advantages
- High strength — 610 MPa (88.5 ksi), better than 99% of aluminum grades
- Tough — resists crack growth — 32 MPa·√m (29.1 ksi·√in), better than 83% of aluminum grades
Limitations
- Difficult to weld — 15/100, worse than 96% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
7055-T77 properties
Typical room-temperature values for 7055-T77; 22 are specific to this condition. Other listed values are 7055 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7055-T77 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% of aluminum grades. It melts at 475°C (887 °F).
Mechanical13
7055-T77 has a yield strength of 610 MPa (88.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 99% of aluminum grades. Elongation at break is 10% and the elastic modulus is 70.5 GPa (10.2 Msi).
Thermal6
7055-T77 is rated for continuous service to 120°C (248 °F). It conducts heat at 154 W/m·K (89 BTU/hr·ft·°F), better than 68% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7055-T77 conducts electricity at 37 % IACS, better than 58% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (44/100), worse than 65% of aluminum grades.
Sustainability4
Producing a kilogram of 7055-T77 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
7055-T77's machinability is good (62/100, better than 55% of aluminum grades); weldability poor (15/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7055-T77
Is 7055 easy to machine?
Machines well with sharp carbide tooling, high speed and generous coolant; expect springy chips and watch residual-stress distortion when hogging thick plate.
Can 7055 be welded?
Not fusion weldable in structural applications — use mechanical fastening, adhesive bonding or FSW with qualified procedures.
Can 7055 be formed, bent or molded?
Essentially a machine-from-solid/extrude alloy; cold form only in the W condition with large bend radii, hot form 350–420 °C then re-solution and overage.
What surface finishes work on 7055?
Chromic/sulfuric or hardcoat anodize plus primer for corrosion protection; conversion coating and epoxy primer is the standard aerospace route, avoid caustic etches that pit Cu-rich phases.
7055 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 | 0.05 |
| Fe | ≤ 0.15 | 0.08 |
| Cu | 2 – 2.6 | 2.3 |
| Mn | ≤ 0.05 | 0.02 |
| Mg | 1.8 – 2.3 | 2.05 |
| Cr | ≤ 0.04 | 0.02 |
| Zn | 7.6 – 8.4 | 8 |
| Ti | ≤ 0.06 | 0.03 |
| Zrdispersoid former | 0.08 – 0.25 | 0.13 |
| Others (each)0.15 total | ≤ 0.05 | — |
| Al | balance | — |
7055-T77 — frequently asked
What is 7055-T77 used for?
7055-T77 is typically used for upper wing skins, wing stringers and extrusions, keel members, compression-loaded airframe structure, machined spar and rib details and high-strength aerospace fittings. In short: highest strength 7000 series.
What is the yield strength of 7055-T77?
7055-T77 has a typical yield strength of 610 MPa (88.5 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 99% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 7055-T77 easy to machine?
Reasonably — machinability is rated good (62/100, better than 55% of aluminum grades). Machines well with sharp carbide tooling, high speed and generous coolant; expect springy chips and watch residual-stress distortion when hogging thick plate.
Can 7055-T77 be welded?
Not readily — weldability is rated poor (15/100). Not fusion weldable in structural applications — use mechanical fastening, adhesive bonding or FSW with qualified procedures.
What surface finishes work on 7055-T77?
Chromic/sulfuric or hardcoat anodize plus primer for corrosion protection; conversion coating and epoxy primer is the standard aerospace route, avoid caustic etches that pit Cu-rich phases.
Can 7055-T77 be formed, bent or molded?
Essentially a machine-from-solid/extrude alloy; cold form only in the W condition with large bend radii, hot form 350–420 °C then re-solution and overage.
What is the maximum service temperature of 7055-T77?
7055-T77 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.
Can FabDigit make parts in 7055-T77?
Yes — 7055-T77 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- Registration Record of International Alloy Designations (Teal Sheets) — The Aluminum Association (2018)
- MMPDS-17 Metallic Materials Properties Development and Standardization — Battelle/FAA (2022)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- 7055 Alloy Plate and Extrusion Data — Alcoa / Arconic (2016)
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.