Aluminum 7A04-T651
Temper
GB 7A04
T651 = t6, stress relieved by stretching
Thick plate temper of choice when large amounts of metal are machined away and distortion must be minimized.
Values for the T651 condition
Other 7A04 tempers and conditions
7A04 is listed in 9 conditions; see the grade overview at 7A04.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest state for deep forming, bending or straightening before re-heat-treatment. | 110 | 235 | 16 | 60 HB | 45 % IACS |
As fabricated | Mill state of forging stock and hot-rolled slabs, bought for subsequent forging plus full heat treatment. | 200 | 320 | 12 | 90 HB | 40 % IACS |
Solution heat treated and naturally aged | Intermediate strength with better formability than T6; used when parts are formed after quenching and later artificially aged. | 300 | 470 | 13 | 120 HB | 32 % IACS |
T73, stress relieved by stretching | Thick-plate over-aged temper for machined aerospace fittings needing both low residual stress and SCC resistance. | 420 | 490 | 9 | 132 HB | 40 % IACS |
Solution heat treated and overaged for stress-corrosion resistance | Pick when stress-corrosion cracking or exfoliation risk (thick sections, sustained tension, marine/humid service) outweighs the ~8 % strength loss. | 430 | 500 | 10 | 135 HB | 40 % IACS |
Overaged for exfoliation-corrosion resistance | Compromise temper: most of T6 strength with much better exfoliation resistance in thin plate and extrusions. | 450 | 520 | 9 | 140 HB | 38 % IACS |
T6, heat treated by the user | Used when parts are formed in the O/F state and then given a full T6 treatment by the fabricator. | 460 | 530 | 8 | 145 HB | 33 % IACS |
T651This page T6, stress relieved by stretching | Thick plate temper of choice when large amounts of metal are machined away and distortion must be minimized. | 470 | 540 | 8 | 148 HB | 33 % IACS |
T6Default Solution heat treated and artificially aged | Standard peak-strength condition for machined structural parts, extrusions and forgings; default stock temper. | 475 | 545 | 8 | 150 HB | 33 % IACS |
What is 7A04-T651?
7A04-T651 is 7A04 in the T651 temper — thick plate temper of choice when large amounts of metal are machined away and distortion must be minimized. 7A04-T651 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 540 MPa (78.3 ksi) — stronger than 93% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi). 7A04-T651 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% 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 — 470 MPa (68.2 ksi), better than 93% of aluminum grades
- Easy to machine — 75/100, better than 86% of aluminum grades
Limitations
- High embodied carbon — 14 kg CO₂/kg, worse than 95% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
- Needs corrosion protection — 35/100, worse than 85% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
7A04-T651 properties
Typical room-temperature values for 7A04-T651; 22 are specific to this condition. Other listed values are 7A04 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7A04-T651 has a density of 2.85 g/cm³ (0.103 lb/in³), heavier than 96% of aluminum grades. It melts at 477°C (891 °F).
Mechanical14
7A04-T651 has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 540 MPa (78.3 ksi) — stronger than 93% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
7A04-T651 is rated for continuous service to 120°C (248 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7A04-T651 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 85% of aluminum grades.
Sustainability4
Producing a kilogram of 7A04-T651 takes about 200 MJ of energy and emits 14 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 10%.
Manufacturability6
7A04-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 7A04-T651
Is 7A04 easy to machine?
Machines very freely in T6/T73 with sharp polished-flute carbide tools, high speeds and flood coolant/MQL; watch residual-stress distortion on thick plate — use T651/T7351 and symmetric roughing passes.
Can 7A04 be welded?
Not suitable for fusion welding (hot cracking, severe HAZ strength loss); join by riveting, bolting or adhesive, or use friction-stir/resistance spot welding with post-weld property allowance.
Can 7A04 be formed, bent or molded?
Form in O or T4 (or hot-form 200–350 °C) with generous bend radii; T6 material is prone to cracking, and forgings need controlled 400–460 °C forging plus solution quench.
What surface finishes work on 7A04?
Anodize (sulfuric, chromic or hard Type III), chromate/trivalent conversion coat plus epoxy primer for aerospace; avoid strong alkaline cleaners and give shot-peening on fatigue-critical surfaces.
7A04 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 | 5 – 7 | 6 |
| Mg | 1.8 – 2.8 | 2.3 |
| Cu | 1.4 – 2 | 1.7 |
| Mn | 0.2 – 0.6 | 0.4 |
| Cr | 0.1 – 0.25 | 0.17 |
| Feimpurity limit | ≤ 0.5 | — |
| Siimpurity limit | ≤ 0.5 | — |
| Tigrain refiner / impurity | ≤ 0.1 | — |
| Niimpurity limit | ≤ 0.1 | — |
| others (each)total 0.10 max | ≤ 0.05 | — |
| Al | balance | — |
7A04-T651 — frequently asked
What is 7A04-T651 used for?
7A04-T651 is typically used for aircraft structural forgings, high-strength machined parts and landing gear components. In short: 7075-class strength level; high-strength forging grade; not fusion weldable.
What is the yield strength of 7A04-T651?
7A04-T651 has a typical yield strength of 470 MPa (68.2 ksi) and a tensile strength of 540 MPa (78.3 ksi) — stronger than 93% of aluminum grades. Strength varies by condition: see the 9 listed tempers.
Is 7A04-T651 easy to machine?
Yes — machinability is rated very good (75/100, better than 86% of aluminum grades). Machines very freely in T6/T73 with sharp polished-flute carbide tools, high speeds and flood coolant/MQL; watch residual-stress distortion on thick plate — use T651/T7351 and symmetric roughing passes.
Can 7A04-T651 be welded?
Not readily — weldability is rated poor (20/100). Not suitable for fusion welding (hot cracking, severe HAZ strength loss); join by riveting, bolting or adhesive, or use friction-stir/resistance spot welding with post-weld property allowance.
What surface finishes work on 7A04-T651?
Anodize (sulfuric, chromic or hard Type III), chromate/trivalent conversion coat plus epoxy primer for aerospace; avoid strong alkaline cleaners and give shot-peening on fatigue-critical surfaces.
Can 7A04-T651 be formed, bent or molded?
Form in O or T4 (or hot-form 200–350 °C) with generous bend radii; T6 material is prone to cracking, and forgings need controlled 400–460 °C forging plus solution quench.
What is the maximum service temperature of 7A04-T651?
7A04-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 7A04-T6 and 7A04-O?
T6 is the default condition — standard peak-strength condition for machined structural parts, extrusions and forgings; default stock temper. O: softest state for deep forming, bending or straightening before re-heat-treatment. Yield strength is 475 MPa in T6 versus 110 MPa in O.
Sources
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (7075) — ASM International (1990)
- MMPDS-17 Metallic Materials Properties Development and Standardization — Battelle/FAA (2022)
- Aluminum Association Teal Sheets — registered alloy/temper data — The Aluminum Association (2018)
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.