Aluminum 7079-T651
Temper
AA 7079 · UNS A97079
T651 = t6, stress relieved by stretching
Thick-plate temper with low residual stress for machined aircraft fittings and bulkheads.
Values for the T651 condition
Other 7079 tempers and conditions
7079 is listed in 7 conditions; see the grade overview at 7079.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for forming, straightening or re-heat-treating; no service strength. | 110 | 235 | 16 | 62 HB | 45 % IACS |
Solution heat treated (unstable) | Freshly quenched, refrigerated condition used only as a short forming/riveting window before ageing to T6. | 230 | 380 | 17 | 95 HB | 30 % IACS |
T6, stress relieved by compression | Forging temper where residual stress is knocked down by cold compression before ageing — the classic 7079 thick-forging condition. | 448 | 517 | 10 | 140 HB | 33.5 % IACS |
T651This page T6, stress relieved by stretching | Thick-plate temper with low residual stress for machined aircraft fittings and bulkheads. | 455 | 524 | 11 | 142 HB | 33.5 % IACS |
Solution treated, stretched, aged; permissible minor straightening | Extruded shapes/bar where tight straightness and low residual stress are needed and minor straightening is allowed. | 460 | 530 | 10 | 143 HB | 33.5 % IACS |
T6, stress relieved by stretching, minor straightening | As T6510 but with the tightest residual-stress control for parts machined to close tolerance from extrusion. | 460 | 530 | 10 | 143 HB | 33.5 % IACS |
T6Default Solution heat treated and artificially aged | Standard peak-aged condition for die forgings and extrusions; highest strength but poorest SCC resistance. | 469 | 538 | 14 | 145 HB | 33.5 % IACS |
What is 7079-T651?
7079-T651 is 7079 in the T651 temper — thick-plate temper with low residual stress for machined aircraft fittings and bulkheads. 7079-T651 has a yield strength of 455 MPa (66 ksi) and a tensile strength of 524 MPa (76 ksi) — stronger than 92% of aluminum grades. Elongation at break is 11% and the elastic modulus is 71.7 GPa (10.4 Msi). 7079-T651 has a density of 2.74 g/cm³ (0.099 lb/in³), heavier than 64% of aluminum grades. It melts at 477°C (891 °F). T6 is the default condition FabDigit quotes; T651 is available on request or by drawing note.
Advantages
- High strength — 455 MPa (66 ksi), better than 92% of aluminum grades
- Easy to machine — 74/100, better than 85% of aluminum grades
Limitations
- Needs corrosion protection — 26/100, worse than 100% of aluminum grades
- Difficult to weld — 15/100, worse than 96% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
- Poor heat conductor — 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades
7079-T651 properties
Typical room-temperature values for 7079-T651; 11 are specific to this condition. Other listed values are 7079 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7079-T651 has a density of 2.74 g/cm³ (0.099 lb/in³), heavier than 64% of aluminum grades. It melts at 477°C (891 °F).
Mechanical13
7079-T651 has a yield strength of 455 MPa (66 ksi) and a tensile strength of 524 MPa (76 ksi) — stronger than 92% of aluminum grades. Elongation at break is 11% and the elastic modulus is 71.7 GPa (10.4 Msi).
Thermal6
7079-T651 is rated for continuous service to 120°C (248 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades. Thermal expansion is 24.3 µm/m·K (13.5 µin/in·°F).
Electrical3
7079-T651 conducts electricity at 33.5 % IACS, worse than 54% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (26/100), worse than 100% of aluminum grades.
Sustainability4
Producing a kilogram of 7079-T651 takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 8%.
Manufacturability8
7079-T651's machinability is very good (74/100, better than 85% of aluminum grades); weldability poor (15/100); formability poor (28/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7079-T651
Is 7079 easy to machine?
Machines like 7075-T6 — free-cutting in the aged condition with sharp carbide tools, high speeds and flood coolant; stress-relieved tempers (T651/T652/T6511) are essential to avoid distortion when hogging thick sections.
Can 7079 be welded?
Not arc weldable for structural use (hot cracking and severe HAZ SCC); join by rivets, bolts or bonding, and repair only by mechanical means.
Can 7079 be formed, bent or molded?
Form in O or freshly quenched W condition then age; cold forming in T6 is limited to large-radius bends because ductility and SCC resistance are low.
What surface finishes work on 7079?
Responds well to sulfuric and hard anodizing and to chromate/trivalent conversion coating plus epoxy primer — protective coating and avoidance of short-transverse sustained tension are mandatory for corrosion control.
7079 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 |
|---|---|---|
| Zn | 3.8 – 4.8 | 4.3 |
| Mg | 2.9 – 3.7 | 3.3 |
| Cu | 0.4 – 0.8 | 0.6 |
| Mn | 0.1 – 0.3 | 0.2 |
| Cr | 0.1 – 0.25 | 0.18 |
| Fe | ≤ 0.4 | — |
| Si | ≤ 0.3 | — |
| Ti | ≤ 0.1 | — |
| Others (each)others total 0.15 max | ≤ 0.05 | — |
| Al | balance | — |
7079-T651 — frequently asked
What is 7079-T651 used for?
7079-T651 is typically used for legacy aircraft forgings, thick-section structural fittings, replacement parts for older airframes, machined forged brackets and lugs, heavy-gauge plate structures and hogged-out structural housings. In short: legacy aerospace forging alloy; superseded by 7075/7050; thick-section high strength.
What is the yield strength of 7079-T651?
7079-T651 has a typical yield strength of 455 MPa (66 ksi) and a tensile strength of 524 MPa (76 ksi) — stronger than 92% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 7079-T651 easy to machine?
Yes — machinability is rated very good (74/100, better than 85% of aluminum grades). Machines like 7075-T6 — free-cutting in the aged condition with sharp carbide tools, high speeds and flood coolant; stress-relieved tempers (T651/T652/T6511) are essential to avoid distortion when hogging thick sections.
Can 7079-T651 be welded?
Not readily — weldability is rated poor (15/100). Not arc weldable for structural use (hot cracking and severe HAZ SCC); join by rivets, bolts or bonding, and repair only by mechanical means.
What surface finishes work on 7079-T651?
Responds well to sulfuric and hard anodizing and to chromate/trivalent conversion coating plus epoxy primer — protective coating and avoidance of short-transverse sustained tension are mandatory for corrosion control.
Can 7079-T651 be formed, bent or molded?
Form in O or freshly quenched W condition then age; cold forming in T6 is limited to large-radius bends because ductility and SCC resistance are low.
What is the maximum service temperature of 7079-T651?
7079-T651 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 7079-T6 and 7079-O?
T6 is the default condition — standard peak-aged condition for die forgings and extrusions; highest strength but poorest SCC resistance. O: softest condition for forming, straightening or re-heat-treating; no service strength. Yield strength is 469 MPa in T6 versus 110 MPa in O.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (Al alloy SCC behavior) — ASM International (2005)
- MMPDS / MIL-HDBK-5 legacy aluminum forging and plate allowables — FAA / Battelle (2003)
- Aluminum Standards and Data (legacy temper listings for 7079) — The Aluminum Association (2013)
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.