Aluminum 6061-O vs 6061-T4
Aluminum · 6061 temper comparison
6061-O and 6061-T4 are two conditions of the same aluminum grade, 6061: O (annealed) versus T4 (solution heat treated and naturally aged). The chemistry is identical, so every difference below comes from the condition. 6061-T4 is the stronger of the two: yield strength 145 MPa (21 ksi) against 55 MPa (7.98 ksi) for 6061-O, about 164% more; tensile strength follows at 241 MPa (35 ksi) vs 124 MPa (18 ksi). In exchange, 6061-O is the more ductile: elongation 27% versus 22% for 6061-T4, and 6061-T4 is harder (65 HB vs 30 HB). 6061-O runs hotter in service (200°C vs 120°C continuous) and 6061-O conducts heat better (180 W/m·K vs 154 W/m·K). On the shop floor, 6061-T4 machines more easily (good vs fair).
6061-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
6061-T4Choose it when strength drives the design, or when the part is machined in volume.
6061-O vs 6061-T4: 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
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 68.9 GPa10 Msi · Shear Modulus 26 GPa3.8 Msi · Bulk Modulus 69 GPa10 Msi · Poisson's Ratio 0.33 · Reduction in Area 40% · Compressive Strength 276 MPa40 ksi · Fracture Toughness (K_IC) 29 MPa·√m26.4 ksi·√in · Charpy V-Notch Impact (RT) 22 J16.2 ft·lbf · Hardness, Rockwell B 60 HRB
Physical
Density and transition temperatures.
Same in both: Density 2.7 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) 23.6 µm/m·K13.1 µin/in·°F · Latent Heat of Fusion 397 J/g171 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.83 V · Corrosion Resistance 55 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Same in both: Weldability 85 / 100 · Brazeability / Solderability 60 / 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) 12.5 kg CO₂/kg · Embodied Water 1,200 L/kg144 gal/lb · Typical Recycled Content 35%
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.
6061-O vs 6061-T4 — frequently asked
Is 6061-T4 stronger than 6061-O?
Yes. 6061-T4 has a typical yield strength of 145 MPa (21 ksi) against 55 MPa (7.98 ksi) for 6061-O — about 164% more. Tensile strength is 241 MPa (35 ksi) vs 124 MPa (18 ksi).
Which condition does FabDigit quote by default, O or T4?
T6 is the default 6061 condition in the FabDigit quote flow (neither O nor T4). 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, 6061-O or 6061-T4?
6061-T4. Its machinability rates good (55/100) against fair (40/100) for 6061-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6061-O and 6061-T4 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.