Aluminum 7055
AA 7055 · UNS A97055 · EN AW-7055, AW 7055
7055 is an ultra-high-strength Al-Zn-Mg-Cu (7000 series) aerospace alloy developed by Alcoa, supplied almost exclusively in the overaged T77-type tempers (T7751 plate, T77511 extrusions).
7055 tempers and conditions
7055 is supplied in 4 conditions, soft to hard.
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 |
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?
7055 is an ultra-high-strength Al-Zn-Mg-Cu (7000 series) aerospace alloy developed by Alcoa, supplied almost exclusively in the overaged T77-type tempers (T7751 plate, T77511 extrusions). In T7751 it delivers roughly 10 % higher strength than 7150-T7751 while keeping acceptable exfoliation and stress-corrosion resistance, which is why it is used for compression-dominated structure such as upper wing skins, stringers and keel members. Limits are modest fracture toughness and fatigue crack growth resistance, essentially no fusion weldability, poor cold formability, and high price/limited stock outside aerospace supply chains. 7055 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). 7055 has a yield strength of 634 MPa (92 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 99% of aluminum grades. Elongation at break is 11% and the elastic modulus is 70.5 GPa (10.2 Msi).
What is 7055 used for?
- Upper wing skins
- Wing stringers and extrusions
- Keel members
- Compression-loaded airframe structure
- Machined spar and rib details
- High-strength aerospace fittings
Advantages
- High strength — 634 MPa (92 ksi), better than 99% of aluminum grades
- Tough — resists crack growth — 31 MPa·√m (28.2 ksi·√in), better than 80% 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 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
7055 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 has a yield strength of 634 MPa (92 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 99% of aluminum grades. Elongation at break is 11% and the elastic modulus is 70.5 GPa (10.2 Msi).
Thermal6
7055 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 conducts electricity at 37 % IACS, better than 58% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 69% of aluminum grades.
Sustainability4
Producing a kilogram of 7055 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's machinability is good (62/100, better than 55% of aluminum grades); weldability poor (15/100); formability poor (20/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the aluminum family
Yield strength against density for every aluminum grade FabDigit runs. 7055 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7055
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.
Manufacturability
The process limits FabDigit applies to 7055. Every 7055 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Excellent62 / 100 |
|---|---|
| ISO material group | N.1 |
| Cutting speed (rough / finish) | 350 / 420 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 8× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Not Recommend20 / 100 |
|---|---|
| Weldability | Not Recommend15 / 100 |
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 |
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.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Conversion Coating
PVD Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 7055 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A97055
- Aluminum Association
- AA7055
- EN / DIN / Werkstoff-Nr.
- AW-7055AW 7055
How much does 7055 cost?
7055 is a high-cost aluminum ($$$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
7055 — frequently asked
What is 7055 used for?
7055 is typically used for upper wing skins, wing stringers and extrusions, keel members, compression-loaded airframe structure, machined spar and rib details and high-strength aerospace fittings. In short: highest strength 7000 series.
What is the yield strength of 7055?
7055 has a typical yield strength of 634 MPa (92 ksi) and a tensile strength of 655 MPa (95 ksi) — stronger than 99% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 7055 easy to machine?
Reasonably — machinability is rated good (62/100, better than 55% of aluminum grades). Machines well with sharp carbide tooling, high speed and generous coolant; expect springy chips and watch residual-stress distortion when hogging thick plate.
Can 7055 be welded?
Not readily — weldability is rated poor (15/100). Not fusion weldable in structural applications — use mechanical fastening, adhesive bonding or FSW with qualified procedures.
What surface finishes work on 7055?
Chromic/sulfuric or hardcoat anodize plus primer for corrosion protection; conversion coating and epoxy primer is the standard aerospace route, avoid caustic etches that pit Cu-rich phases.
Can 7055 be formed, bent or molded?
Essentially a machine-from-solid/extrude alloy; cold form only in the W condition with large bend radii, hot form 350–420 °C then re-solution and overage.
What is the maximum service temperature of 7055?
7055 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 7055 cost?
7055 is a high-cost aluminum ($$$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 7055?
Yes — 7055 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.