Aluminum 6069-T651
Temper
AA 6069 · UNS A96069
T651 = t6, stress relieved by stretching
Plate and rolled bar for machined parts that must stay flat after heavy stock removal.
Values for the T651 condition
Other 6069 tempers and conditions
6069 is listed in 7 conditions; see the grade overview at 6069.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for severe forming, bending or machining before heat treatment. | 75 | 150 | 25 | 45 HB | 48 % IACS |
Solution heat treated and naturally aged | Choose when parts must be formed or bent after solution treatment and later artificially aged to T6. | 180 | 295 | 20 | 80 HB | 42 % IACS |
Cooled from hot working and artificially aged | Press-quenched extrusions where full solution treatment is skipped for cost and distortion control. | 325 | 360 | 10 | 105 HB | 41 % IACS |
Solution heat treated and overaged (stabilized) | Overaged condition traded for better dimensional stability, corrosion resistance and toughness at ~10 % lower strength. | 330 | 370 | 13 | 108 HB | 44 % IACS |
T6Default Solution heat treated and artificially aged | Standard stocked condition: maximum strength for structural extrusions, tube and machined parts. | 380 | 415 | 12 | 120 HB | 40 % IACS |
T651This page T6, stress relieved by stretching | Plate and rolled bar for machined parts that must stay flat after heavy stock removal. | 380 | 415 | 11 | 120 HB | 40 % IACS |
T6, stress relieved by stretching, minor straightening | Standard extruded bar/profile temper where straightness and low residual stress matter for machining. | 385 | 420 | 12 | 122 HB | 40 % IACS |
What is 6069-T651?
6069-T651 is 6069 in the T651 temper — plate and rolled bar for machined parts that must stay flat after heavy stock removal. 6069-T651 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 86% of aluminum grades. Elongation at break is 11% and the elastic modulus is 69.5 GPa (10.1 Msi). 6069-T651 has a density of 2.71 g/cm³ (0.0979 lb/in³), heavier than 51% of aluminum grades. It melts at 580°C (1,076 °F). T6 is the default condition FabDigit quotes; T651 is available on request or by drawing note.
Advantages
- High strength — 380 MPa (55.1 ksi), better than 86% of aluminum grades
- Conducts heat well — 165 W/m·K (95.3 BTU/hr·ft·°F), better than 79% of aluminum grades
6069-T651 properties
Typical room-temperature values for 6069-T651; 10 are specific to this condition. Other listed values are 6069 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
6069-T651 has a density of 2.71 g/cm³ (0.0979 lb/in³), heavier than 51% of aluminum grades. It melts at 580°C (1,076 °F).
Mechanical16
6069-T651 has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 86% of aluminum grades. Elongation at break is 11% and the elastic modulus is 69.5 GPa (10.1 Msi).
Thermal6
6069-T651 is rated for continuous service to 150°C (302 °F). It conducts heat at 165 W/m·K (95.3 BTU/hr·ft·°F), better than 79% of aluminum grades. Thermal expansion is 23.2 µm/m·K (12.9 µin/in·°F).
Electrical3
6069-T651 conducts electricity at 40 % IACS, better than 72% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of 6069-T651 takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
6069-T651's machinability is good (60/100, worse than 51% of aluminum grades); weldability good (60/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 6069-T651
Is 6069 easy to machine?
Machines like a stiffer 6061-T6: high SFM with polished-flute carbide, flood coolant or MQL, chips break better in T6 than in T4/O.
Can 6069 be welded?
GTAW/GMAW with 4043 or 4643 filler is routine, but expect HAZ softening to near-T4 strength unless the assembly is re-solution-treated and aged; avoid pure Al filler.
Can 6069 be formed, bent or molded?
Form, bend or hydroform in O or T4 and age afterwards; T6 tube bending needs generous radii (≥3×D) and mandrel support to avoid cracking.
What surface finishes work on 6069?
Responds well to sulfuric clear and hardcoat anodize (slightly darker/greyer than 6061 from Cu+Si); chromate/Ti-Zr conversion coats and powder paint work normally, and Cu content makes protective coating advisable in marine service.
6069 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 | 0.6 – 1.2 | 0.9 |
| Feimpurity limit | ≤ 0.35 | 0.15 |
| Cumain strength addition vs 6061 | 0.5 – 0.9 | 0.7 |
| Mndispersoid former, grain control | 0.2 – 0.8 | 0.4 |
| Mg | 0.8 – 1.2 | 1 |
| Cr | ≤ 0.3 | 0.15 |
| Zn | ≤ 0.25 | 0.05 |
| Tigrain refiner | ≤ 0.15 | 0.03 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
6069-T651 — frequently asked
What is 6069-T651 used for?
6069-T651 is typically used for high-strength structural extrusions, aerospace fittings and brackets, load-bearing tube and profile, machined structural hardware, transport frame members and bent tubular structures. In short: stronger than 6061-T6; weldable high-strength 6000 series; copper lowers corrosion resistance.
What is the yield strength of 6069-T651?
6069-T651 has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 86% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 6069-T651 easy to machine?
Reasonably — machinability is rated good (60/100, worse than 51% of aluminum grades). Machines like a stiffer 6061-T6: high SFM with polished-flute carbide, flood coolant or MQL, chips break better in T6 than in T4/O.
Can 6069-T651 be welded?
Yes — weldability is rated good (60/100). GTAW/GMAW with 4043 or 4643 filler is routine, but expect HAZ softening to near-T4 strength unless the assembly is re-solution-treated and aged; avoid pure Al filler.
What surface finishes work on 6069-T651?
Responds well to sulfuric clear and hardcoat anodize (slightly darker/greyer than 6061 from Cu+Si); chromate/Ti-Zr conversion coats and powder paint work normally, and Cu content makes protective coating advisable in marine service.
Can 6069-T651 be formed, bent or molded?
Form, bend or hydroform in O or T4 and age afterwards; T6 tube bending needs generous radii (≥3×D) and mandrel support to avoid cracking.
What is the maximum service temperature of 6069-T651?
6069-T651 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 6069-T6 and 6069-O?
T6 is the default condition — standard stocked condition: maximum strength for structural extrusions, tube and machined parts. O: softest condition for severe forming, bending or machining before heat treatment. Yield strength is 380 MPa in T6 versus 75 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 — ASM International (1990)
- MMPDS-17 typical property data for 6000-series wrought alloys — Battelle/FAA (2022)
- High-strength 6069 extrusion product literature — Aluminum extruder (Alcoa/Universal Alloy lineage) (2015)
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.