Aluminum 7A85-T651
Temper
GB 7A85
T651 = t6, stress relieved by stretching
Peak-strength plate temper — pick when maximum static strength matters more than SCC/exfoliation resistance.
Values for the T651 condition
Other 7A85 tempers and conditions
7A85 is listed in 8 conditions; see the grade overview at 7A85.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition, supplied for deep forming or machining of blanks before solution treatment. | 115 | 240 | 16 | 65 HB | 45 % IACS |
As fabricated | Mill product before heat treatment; properties not guaranteed, used as feedstock for forging or further heat treat. | 180 | 300 | 12 | 85 HB | 44 % IACS |
T73, stress relieved by stretching | Maximum SCC immunity for highly stressed thick sections, at the cost of ~8–10 % strength versus T7451. | 425 | 480 | 11 | 145 HB | 42 % IACS |
Solution treated, stress relieved by compression, over-aged | Standard temper for large 7A85 die forgings and hand forgings where stretching is impossible. | 455 | 500 | 9 | 152 HB | 40 % IACS |
T7451Default T74, stress relieved by stretching | Standard thick-plate aerospace temper: best balance of strength, through-thickness toughness and SCC resistance. | 470 | 510 | 10 | 155 HB | 40 % IACS |
T76, stress relieved by stretching | Slightly less over-aged than T74 — higher strength with good exfoliation resistance, typical for medium-thickness plate and skins. | 490 | 530 | 9 | 162 HB | 38 % IACS |
Extruded, solution treated, stretched, over-aged to T76 | Extruded stringers and profiles needing exfoliation resistance with near-peak strength. | 500 | 540 | 9 | 165 HB | 38 % IACS |
T651This page T6, stress relieved by stretching | Peak-strength plate temper — pick when maximum static strength matters more than SCC/exfoliation resistance. | 520 | 560 | 8 | 175 HB | 32 % IACS |
What is 7A85-T651?
7A85-T651 is 7A85 in the T651 temper — peak-strength plate temper — pick when maximum static strength matters more than SCC/exfoliation resistance. 7A85-T651 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 97% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi). 7A85-T651 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% of aluminum grades. It melts at 476°C (889 °F). T7451 is the default condition FabDigit quotes; T651 is available on request or by drawing note.
Advantages
- High strength — 520 MPa (75.4 ksi), better than 97% of aluminum grades
- Easy to machine — 75/100, better than 86% of aluminum grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 76% of aluminum grades
Limitations
- Needs corrosion protection — 32/100, worse than 94% 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
7A85-T651 properties
Typical room-temperature values for 7A85-T651; 13 are specific to this condition. Other listed values are 7A85 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7A85-T651 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% of aluminum grades. It melts at 476°C (889 °F).
Mechanical14
7A85-T651 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 97% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
7A85-T651 is rated for continuous service to 100°C (212 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 23.6 µm/m·K (13.1 µin/in·°F).
Electrical3
7A85-T651 conducts electricity at 32 % IACS, worse than 63% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (32/100), worse than 94% of aluminum grades.
Sustainability4
Producing a kilogram of 7A85-T651 takes about 210 MJ of energy and emits 13 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 5%.
Manufacturability8
7A85-T651's machinability is very good (75/100, better than 86% of aluminum grades); weldability poor (20/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7A85-T651
Is 7A85 easy to machine?
Machines cleanly in T7x with sharp polished-flute carbide tools, high speed and flood coolant; watch residual-stress distortion when hogging thick plate — rough, stress-relieve/rest, then finish.
Can 7A85 be welded?
Not recommended for fusion welding (hot cracking, severe HAZ softening and SCC); join by fasteners or friction stir welding with post-weld aging where qualified.
Can 7A85 be formed, bent or molded?
Form in O or freshly solution-treated W temper; T7x plate is essentially limited to gentle bends with large radii, so most parts are machined from plate or die-forged.
What surface finishes work on 7A85?
Chromic/sulfuric or hard anodize plus chromate-free conversion coat and primer is standard; expect grey anodic film, avoid bright decorative finishes; shot peening improves SCC and fatigue life.
7A85 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 |
|---|---|---|
| Znprincipal strengthening addition | 7 – 8 | 7.5 |
| Mg | 1.2 – 1.8 | 1.5 |
| Cuimproves SCC resistance in over-aged tempers | 1.3 – 2 | 1.6 |
| ZrAl3Zr dispersoids; replaces Cr for low quench sensitivity | 0.08 – 0.15 | 0.11 |
| Feheld low for fracture toughness | ≤ 0.08 | 0.05 |
| Si | ≤ 0.06 | 0.04 |
| Mn | ≤ 0.04 | — |
| Cr | ≤ 0.04 | — |
| Ti | ≤ 0.06 | — |
| other, each | ≤ 0.05 | — |
| other, total | ≤ 0.15 | — |
| Al | balance | — |
7A85-T651 — frequently asked
What is 7A85-T651 used for?
7A85-T651 is typically used for aircraft bulkheads, thick plate structural forgings and high-toughness aerospace parts. In short: thick-section 7000-series grade; low quench sensitivity; high toughness at 470 MPa.
What is the yield strength of 7A85-T651?
7A85-T651 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 97% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 7A85-T651 easy to machine?
Yes — machinability is rated very good (75/100, better than 86% of aluminum grades). Machines cleanly in T7x with sharp polished-flute carbide tools, high speed and flood coolant; watch residual-stress distortion when hogging thick plate — rough, stress-relieve/rest, then finish.
Can 7A85-T651 be welded?
Not readily — weldability is rated poor (20/100). Not recommended for fusion welding (hot cracking, severe HAZ softening and SCC); join by fasteners or friction stir welding with post-weld aging where qualified.
What surface finishes work on 7A85-T651?
Chromic/sulfuric or hard anodize plus chromate-free conversion coat and primer is standard; expect grey anodic film, avoid bright decorative finishes; shot peening improves SCC and fatigue life.
Can 7A85-T651 be formed, bent or molded?
Form in O or freshly solution-treated W temper; T7x plate is essentially limited to gentle bends with large radii, so most parts are machined from plate or die-forged.
What is the maximum service temperature of 7A85-T651?
7A85-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 7A85-T7451 and 7A85-O?
T7451 is the default condition — standard thick-plate aerospace temper: best balance of strength, through-thickness toughness and SCC resistance. O: softest condition, supplied for deep forming or machining of blanks before solution treatment. Yield strength is 470 MPa in T7451 versus 115 MPa in O.
Sources
- GB/T 3190 Wrought aluminium and aluminium alloys — Chemical composition — SAC (2020)
- GB/T 3880 / GB/T 3191 aluminium plate and extrusion product standards — SAC (2021)
- Aluminum Association Teal Sheets — Registration Record of Alloy Designations (7085 reference) — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- MMPDS-17 Metallic Materials Properties Development and Standardization — FAA/Battelle (2022)
- Thick aerospace plate 7085/7A85-T7451 datasheets — Arconic / Southwest Aluminium (2022)
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.