Aluminum 6151-O vs 6151-T4
Aluminum · 6151 temper comparison
6151-O and 6151-T4 are two conditions of the same aluminum grade, 6151: O (annealed) versus T4 (solution heat treated and naturally aged). The chemistry is identical, so every difference below comes from the condition. 6151-T4 is the stronger of the two: yield strength 125 MPa (18.1 ksi) against 60 MPa (8.7 ksi) for 6151-O, about 108% more; tensile strength follows at 220 MPa (31.9 ksi) vs 130 MPa (18.9 ksi). In exchange, 6151-O is the more ductile: elongation 25% versus 22% for 6151-T4, and 6151-T4 is harder (65 HB vs 35 HB). 6151-O runs hotter in service (150°C vs 100°C continuous) and 6151-O conducts heat better (205 W/m·K vs 165 W/m·K). On the shop floor, 6151-T4 machines more easily (50 vs 35 out of 100).
6151-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
6151-T4Choose it when strength drives the design, or when the part is machined in volume.
6151-O vs 6151-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
Same in both: Elastic (Young's) Modulus 69 GPa10 Msi · Shear Modulus 26 GPa3.8 Msi · Bulk Modulus 69 GPa10 Msi · Poisson's Ratio 0.33 · Fracture Toughness (K_IC) 30 MPa·√m27.3 ksi·√in · Hardness, Rockwell B 60 HRB · Hardness, Vickers 107 HV
Physical
Density and transition temperatures.
Same in both: Density 2.7 g/cm³0.1 lb/in³ · Melting Point (Solidus) 588°C1,090 °F · Liquidus Temperature 649°C1,200 °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 895 J/kg·K0.21 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 23 µm/m·K12.8 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 4×10⁻⁸ Ω·m1.57 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.83 V · Corrosion Resistance 60 / 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 %) 50% · Castability 40 / 100 · Brazeability / Solderability 45 / 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 1,150 L/kg138 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.
6151-O vs 6151-T4 — frequently asked
Is 6151-T4 stronger than 6151-O?
Yes. 6151-T4 has a typical yield strength of 125 MPa (18.1 ksi) against 60 MPa (8.7 ksi) for 6151-O — about 108% more. Tensile strength is 220 MPa (31.9 ksi) vs 130 MPa (18.9 ksi).
Which condition does FabDigit quote by default, O or T4?
Specify the condition in the material field or the drawing note; FabDigit prices the quote for the state you call out.
Which is easier to machine, 6151-O or 6151-T4?
6151-T4, by a small margin. Both rate fair for machinability — 50/100 against 35/100 for 6151-O; for welding the order is 6151-O first (very good, 75/100) then 6151-T4 (very good, 70/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6151-O and 6151-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.