Aluminum 7040 · temper
Aluminum 7040-T651
Properties of the T651 condition, compared with the other 7040 tempers.
T6 strength with stretch stress relief so heavily machined plate stays dimensionally stable.
What is 7040-T651?
7040-T651 is 7040 in the T651 temper — t6 strength with stretch stress relief so heavily machined plate stays dimensionally stable. 7040-T651 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi). 7040-T651 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). T7451 is the default condition FabDigit quotes; T651 is available on request or by drawing note.
Advantages
- High strength — 505 MPa (73.2 ksi), better than 96% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Needs corrosion protection — 30/100, worse than 98% of aluminum grades
- Limited service temperature — 100°C (212 °F), worse than 91% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
7040-T651 properties
Typical room-temperature values for 7040-T651 — 10 properties are specific to this condition; the rest are grade-level values shared by every 7040 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
7040-T651 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-T651 has a yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
7040-T651 is rated for continuous service to 100°C (212 °F). It conducts heat at 131 W/m·K (75.7 BTU/hr·ft·°F), worse than 61% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7040-T651 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), worse than 98% of aluminum grades.
Sustainability4
Producing a kilogram of 7040-T651 takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 75% of aluminum grades. Typical recycled content is 10%.
Manufacturability7
7040-T651's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (20/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 7040 tempers and conditions
7040 is also supplied in 6 other conditions. The full side-by-side table is on the 7040 overview.
- T7451DefaultThe 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 MPa yield · 145 HB
- T6Choose when maximum static strength matters and exfoliation/SCC exposure is low; toughness and stress-corrosion resistance are the lowest of the aged tempers.510 MPa yield · 165 HB
- T651T6 strength with stretch stress relief so heavily machined plate stays dimensionally stable.505 MPa yield · 163 HB
- T7651Choose when high strength plus exfoliation-corrosion resistance is needed in moderately thick plate; toughness a little below T7451.480 MPa yield · 153 HB
- T7351Pick for the most SCC-critical thick sections where toughness beats peak strength.425 MPa yield · 138 HB
- OPick for maximum formability or before re-solution heat treating; strength is far below service level.115 MPa yield · 65 HB
Working with 7040-T651
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.
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.
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 | — |
7040-T651 — frequently asked
What is 7040-T651 used for?
7040-T651 is typically used for wing spars, bulkheads and heavy frames. In short: thick aerospace plate.
What is the yield strength of 7040-T651?
7040-T651 has a typical yield strength of 505 MPa (73.2 ksi) and a tensile strength of 565 MPa (81.9 ksi) — stronger than 96% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 7040-T651 easy to machine?
Yes — machinability is rated very good (72/100, better than 80% 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-T651 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-T651?
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-T651 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-T651?
7040-T651 is rated for continuous use to about 100°C (212 °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.
Can FabDigit make parts in 7040-T651?
Yes — 7040-T651 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
- 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.