Aluminum 6061-T6 vs 6061-T651
Aluminum · 6061 temper comparison
6061-T6 and 6061-T651 are two conditions of the same aluminum grade, 6061: T6 (solution heat treated and artificially aged) versus T651 (T6, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. Both yield at about 276 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (solution heat treated and artificially aged versus T6, stress relieved by stretching). For most parts the choice follows the drawing's specified condition; ask for the one your standard calls out.
6061-T6 vs 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.
Elongation at Break
Reduction in Area
Fracture Toughness (K_IC)
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 · Tensile Strength (Ultimate) 310 MPa45 ksi · Yield Strength (0.2% offset) 276 MPa40 ksi · Compressive Strength 276 MPa40 ksi · Shear Strength 207 MPa30 ksi · Fatigue Strength (Endurance Limit) 96 MPa13.9 ksi · Charpy V-Notch Impact (RT) 22 J16.2 ft·lbf · Hardness, Brinell 95 HB · 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) 582°C1,080 °F · Liquidus Temperature 652°C1,206 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 167 W/m·K96.5 BTU/hr·ft·°F · 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 · Max Service Temperature (continuous) 170°C338 °F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Same in both: Electrical Conductivity 43 % IACS
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-T6 vs 6061-T651 — frequently asked
What is the difference between 6061-T6 and 6061-T651?
6061-T6 and 6061-T651 are two conditions of the same aluminum grade, 6061: T6 (solution heat treated and artificially aged) versus T651 (T6, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. Both yield at about 276 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (solution heat treated and artificially aged versus T6, stress relieved by stretching).
Which condition does FabDigit quote by default, T6 or T651?
T6 is the default 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.
Which is easier to machine, 6061-T6 or 6061-T651?
6061-T651, by a small margin. Both rate very good for machinability — 75/100 against 70/100 for 6061-T6.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6061-T6 and 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.