Aluminum 7040
AA 7040 · EN AW-7040, AW 7040
7040 is a heat-treatable Al-Zn-Mg-Cu (7000 series) wrought alloy that uses zirconium rather than chromium as the recrystallisation inhibitor, developed for aerospace thick plate in 50–200 mm sections.
Values for the T7451 condition
7040 tempers and conditions
7040 is supplied in 7 conditions, soft to hard. T7451 is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for maximum formability or before re-solution heat treating; strength is far below service level. | 115 | 250 | 15 | 65 HB | 45 % IACS |
As fabricated | Mill intermediate plate for re-heat-treatment by the user; no guaranteed properties. | 180 | 300 | 12 | 90 HB | 44 % IACS |
T73, stress relieved by stretching | Pick for the most SCC-critical thick sections where toughness beats peak strength. | 425 | 490 | 11 | 138 HB | 41.5 % IACS |
T7451Default T74, stress relieved by stretching | The standard supply condition for 7040 aerospace thick plate: near-T6 strength with good through-thickness toughness, SCC resistance and low residual stress for deep machining. | 450 | 505 | 10 | 145 HB | 40.5 % IACS |
T76, stress relieved by stretching | Choose when high strength plus exfoliation-corrosion resistance is needed in moderately thick plate; toughness a little below T7451. | 480 | 530 | 9 | 153 HB | 39 % IACS |
T6, stress relieved by stretching | T6 strength with stretch stress relief so heavily machined plate stays dimensionally stable. | 505 | 565 | 8 | 163 HB | 33 % IACS |
Solution heat treated and artificially aged | Choose when maximum static strength matters and exfoliation/SCC exposure is low; toughness and stress-corrosion resistance are the lowest of the aged tempers. | 510 | 570 | 8 | 165 HB | 33 % IACS |
What is 7040?
7040 is a heat-treatable Al-Zn-Mg-Cu (7000 series) wrought alloy that uses zirconium rather than chromium as the recrystallisation inhibitor, developed for aerospace thick plate in 50–200 mm sections. High hardenability with slightly lower Cu and Mg than 7050/7010 keeps strength uniform through heavy sections and improves fracture toughness and exfoliation/stress-corrosion resistance in the T74/T76 overaged tempers; typical values are 450 MPa yield, 505 MPa tensile, 10 % elongation, 145 HB and 120 °C maximum service temperature. It cannot be fusion welded, relies on cladding, anodizing or coatings for corrosion protection, and is costly with limited plate-only availability. 7040 has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 480°C (896 °F). 7040 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 505 MPa (73.2 ksi) — stronger than 92% of aluminum grades. Elongation at break is 10% and the elastic modulus is 71 GPa (10.3 Msi).
What is 7040 used for?
- Wing spars
- Bulkheads
- Heavy frames
Advantages
- Tough — resists crack growth — 38 MPa·√m (34.6 ksi·√in), better than 96% of aluminum grades
- High strength — 450 MPa (65.3 ksi), better than 92% of aluminum grades
- High electrical conductivity — 40.5 % IACS, better than 76% of aluminum grades
Limitations
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
7040 properties
Typical room-temperature values for 7040-T7451; bars are the position among aluminum grades.
Physical3
7040 has a density of 2.82 g/cm³ (0.102 lb/in³), heavier than 89% of aluminum grades. It melts at 480°C (896 °F).
Mechanical12
7040 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 505 MPa (73.2 ksi) — stronger than 92% of aluminum grades. Elongation at break is 10% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
7040 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
7040 conducts electricity at 40.5 % IACS, better than 76% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 62% of aluminum grades.
Sustainability4
Producing a kilogram of 7040 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
7040's machinability is very good (70/100, better than 72% of aluminum grades); weldability poor (20/100); formability poor (25/100).
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. 7040 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 7040
Is 7040 easy to machine?
Excellent chip formation in T74/T76 tempers — high-speed carbide, polished flutes, 3–8 % emulsion coolant; stretch-relieved plate keeps distortion low on deep pocket milling.
Can 7040 be welded?
Not suitable for fusion welding (hot cracking, SCC in HAZ); join by riveting, bolting or friction-stir welding with qualified procedures.
Can 7040 be formed, bent or molded?
Form in O or freshly quenched W condition only; aged plate has limited bend ductility and needs generous radii and stress-relief planning.
Manufacturability
The process limits FabDigit applies to 7040. Every 7040 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Excellent70 / 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 Recommend25 / 100 |
|---|---|
| Weldability | Not Recommend20 / 100 |
7040 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 | ≤ 0.13 | 0.07 |
| Cu | 1.5 – 2.3 | 1.9 |
| Mn | ≤ 0.04 | 0.01 |
| Mg | 1.7 – 2.4 | 2 |
| Cr | ≤ 0.04 | 0.01 |
| Zn | 5.7 – 6.7 | 6.2 |
| Zrgrain-structure control (Al3Zr dispersoids) | 0.05 – 0.12 | 0.09 |
| Ti | ≤ 0.06 | 0.02 |
| Others (each)each | ≤ 0.05 | |
| Others (total)total | ≤ 0.15 | |
| Al | balance |
What surface finishes work on 7040?
Chromic/tartaric-sulfuric anodize plus primer or hard anodize for wear; alkaline etch and conversion coatings work well, avoid strong caustics and dissimilar-metal contact without insulation.
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 7040 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Aluminum Association
- AA7040
- EN / DIN / Werkstoff-Nr.
- AW-7040AW 7040
How much does 7040 cost?
7040 is a premium-cost aluminum ($$$), cheaper 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.
7040 — frequently asked
What is 7040 used for?
7040 is typically used for wing spars, bulkheads and heavy frames. In short: thick aerospace plate.
What is the yield strength of 7040?
7040 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 505 MPa (73.2 ksi) — stronger than 92% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 7040 easy to machine?
Yes — machinability is rated very good (70/100, better than 72% of aluminum grades). Excellent chip formation in T74/T76 tempers — high-speed carbide, polished flutes, 3–8 % emulsion coolant; stretch-relieved plate keeps distortion low on deep pocket milling.
Can 7040 be welded?
Not readily — weldability is rated poor (20/100). Not suitable for fusion welding (hot cracking, SCC in HAZ); join by riveting, bolting or friction-stir welding with qualified procedures.
What surface finishes work on 7040?
Chromic/tartaric-sulfuric anodize plus primer or hard anodize for wear; alkaline etch and conversion coatings work well, avoid strong caustics and dissimilar-metal contact without insulation.
Can 7040 be formed, bent or molded?
Form in O or freshly quenched W condition only; aged plate has limited bend ductility and needs generous radii and stress-relief planning.
What is the maximum service temperature of 7040?
7040 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 7040-T7451 and 7040-O?
T7451 is the default condition — the standard supply condition for 7040 aerospace thick plate: near-T6 strength with good through-thickness toughness, SCC resistance and low residual stress for deep machining. O: pick for maximum formability or before re-solution heat treating; strength is far below service level. Yield strength is 450 MPa in T7451 versus 115 MPa in O.
How much does 7040 cost?
7040 is a premium-cost aluminum ($$$), cheaper 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 7040?
Yes — 7040 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
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- Aerospace thick plate alloys 7040/7050 (T7451, T7651) plate data — Constellium (formerly Pechiney/Alcan) (2020)
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys — ASM International (1990)
- MMPDS-17 Metallic Materials Properties Development and Standardization — Battelle/FAA (2022)
- EN 485-2 Aluminium and aluminium alloys — Sheet, strip and plate: mechanical properties — CEN (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.