Aluminum 6065-O vs 6065-T651
Aluminum · 6065 temper comparison
6065-O and 6065-T651 are two conditions of the same aluminum grade, 6065: O (annealed) versus T651 (T6, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. 6065-T651 is the stronger of the two: yield strength 370 MPa (53.7 ksi) against 85 MPa (12.3 ksi) for 6065-O, about 4.4 times as much; tensile strength follows at 400 MPa (58 ksi) vs 175 MPa (25.4 ksi). In exchange, 6065-O is the more ductile: elongation 20% versus 10% for 6065-T651, and 6065-T651 is harder (118 HB vs 40 HB). 6065-O runs hotter in service (200°C vs 150°C continuous) and 6065-O conducts electricity better (50 % IACS vs 44 % IACS). On the shop floor, 6065-T651 machines more easily (excellent vs good).
6065-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
6065-T651Choose it when strength drives the design, or when the part is machined in volume.
6065-O vs 6065-T651: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all aluminum grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all aluminum grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 69 GPa10 Msi · Shear Modulus 26 GPa3.8 Msi · Bulk Modulus 68 GPa9.9 Msi · Poisson's Ratio 0.33 · Fatigue Strength (Endurance Limit) 90 MPa13.1 ksi · Fracture Toughness (K_IC) 29 MPa·√m26.4 ksi·√in
Physical
Density and transition temperatures.
Same in both: Density 2.71 g/cm³0.1 lb/in³ · Melting Point (Solidus) 582°C1,080 °F · Liquidus Temperature 652°C1,206 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 896 J/kg·K0.21 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 23.4 µm/m·K13 µin/in·°F · Latent Heat of Fusion 393 J/g169 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 3.9×10⁻⁸ Ω·m1.54 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.74 V · Corrosion Resistance 68 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 90% · Castability 40 / 100 · Brazeability / Solderability 30 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 200 MJ/kg85,985 BTU/lb · Embodied Carbon (primary production) 12 kg CO₂/kg · Embodied Water 1,200 L/kg144 gal/lb · Typical Recycled Content 25%
Strength versus weight
Yield strength against density for every aluminum grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
6065-O vs 6065-T651 — frequently asked
Is 6065-T651 stronger than 6065-O?
Yes. 6065-T651 has a typical yield strength of 370 MPa (53.7 ksi) against 85 MPa (12.3 ksi) for 6065-O — about 4.4 times as much. Tensile strength is 400 MPa (58 ksi) vs 175 MPa (25.4 ksi).
Which condition does FabDigit quote by default, O or T651?
T6 is the default 6065 condition in the FabDigit quote flow (neither O nor T651). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, 6065-O or 6065-T651?
6065-T651. Its machinability rates excellent (90/100) against good (55/100) for 6065-O; for welding the order is 6065-O first (fair, 40/100) then 6065-T651 (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6065-O and 6065-T651 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.