Aluminum B4C/6061-O vs B4C/6061-T651
Aluminum · B4C/6061 temper comparison
B4C/6061-O and B4C/6061-T651 are two conditions of the same aluminum grade, B4C/6061: O (annealed) versus T651 (T6, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. B4C/6061-T651 is the stronger of the two: yield strength 300 MPa (43.5 ksi) against 85 MPa (12.3 ksi) for B4C/6061-O, about 3.5 times as much; tensile strength follows at 345 MPa (50 ksi) vs 165 MPa (23.9 ksi). In exchange, B4C/6061-O is the more ductile: elongation 12% versus 4.5% for B4C/6061-T651, and B4C/6061-T651 is harder (115 HB vs 48 HB). B4C/6061-O runs hotter in service (250°C vs 175°C continuous) and B4C/6061-O conducts electricity better (38 % IACS vs 32 % IACS).
B4C/6061-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
B4C/6061-T651Choose it when strength drives the design.
B4C/6061-O vs B4C/6061-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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 92 GPa13.3 Msi · Shear Modulus 35 GPa5.1 Msi · Bulk Modulus 82 GPa11.9 Msi · Poisson's Ratio 0.32
Physical
Density and transition temperatures.
Same in both: Density 2.67 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 900 J/kg·K0.21 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 20.5 µm/m·K11.4 µin/in·°F · Latent Heat of Fusion 340 J/g146 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.75 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Castability 30 / 100 · Brazeability / Solderability 30 / 100 · Polishability 40 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 235 MJ/kg101,032 BTU/lb · Embodied Carbon (primary production) 14 kg CO₂/kg · Embodied Water 1,200 L/kg144 gal/lb · Typical Recycled Content 5%
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.
B4C/6061-O vs B4C/6061-T651 — frequently asked
Is B4C/6061-T651 stronger than B4C/6061-O?
Yes. B4C/6061-T651 has a typical yield strength of 300 MPa (43.5 ksi) against 85 MPa (12.3 ksi) for B4C/6061-O — about 3.5 times as much. Tensile strength is 345 MPa (50 ksi) vs 165 MPa (23.9 ksi).
Which condition does FabDigit quote by default, O or T651?
T651 is the default B4C/6061 condition in the FabDigit quote flow. 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.
When should I choose B4C/6061-O over B4C/6061-T651?
Pick B4C/6061-O when the part is bent, formed or impact-loaded, or when the part sees heat. Pick B4C/6061-T651 when strength drives the design.
Ready to make it?
Upload a CAD file and FabDigit prices the part in B4C/6061-O and B4C/6061-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.