Aluminum AL9-T4 vs AL9-T6
Aluminum · AL9 temper comparison
AL9-T4 and AL9-T6 are two conditions of the same aluminum grade, AL9: T4 (solution heat treated and naturally aged) versus T6 (solution heat treated and artificially aged). The chemistry is identical, so every difference below comes from the condition. AL9-T6 is the stronger of the two: yield strength 185 MPa (26.8 ksi) against 115 MPa (16.7 ksi) for AL9-T4, about 61% more; tensile strength follows at 240 MPa (34.8 ksi) vs 210 MPa (30.5 ksi). In exchange, AL9-T4 is the more ductile: elongation 8% versus 4% for AL9-T6, and AL9-T6 is harder (80 HB vs 60 HB).
AL9-T4Choose it when the part is bent, formed or impact-loaded.
AL9-T6Choose it when strength drives the design.
AL9-T4 vs AL9-T6: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Same in both: Elastic (Young's) Modulus 72.4 GPa10.5 Msi · Shear Modulus 27 GPa3.9 Msi · Bulk Modulus 75 GPa10.9 Msi · Poisson's Ratio 0.33 · Fracture Toughness (K_IC) 20 MPa·√m18.2 ksi·√in · Hardness, Vickers 85 HV
Physical
Density and transition temperatures.
Same in both: Density 2.68 g/cm³0.1 lb/in³ · Melting Point (Solidus) 557°C1,035 °F · Liquidus Temperature 613°C1,135 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Same in both: Specific Heat Capacity 963 J/kg·K0.23 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 21.5 µm/m·K11.9 µin/in·°F · Latent Heat of Fusion 389 J/g167 BTU/lb · Max Service Temperature (continuous) 150°C302 °F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 4.4×10⁻⁸ Ω·m1.73 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.83 V · Corrosion Resistance 58 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Same in both: Machinability Rating (AISI 1212 = 100 %) 60% · Weldability 80 / 100 · Formability (cold) 10 / 100 · Castability 92 / 100 · Brazeability / Solderability 35 / 100 · Polishability 50 / 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 60%
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.
AL9-T4 vs AL9-T6 — frequently asked
Is AL9-T6 stronger than AL9-T4?
Yes. AL9-T6 has a typical yield strength of 185 MPa (26.8 ksi) against 115 MPa (16.7 ksi) for AL9-T4 — about 61% more. Tensile strength is 240 MPa (34.8 ksi) vs 210 MPa (30.5 ksi).
Which condition does FabDigit quote by default, T4 or T6?
T6 is the default AL9 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, AL9-T4 or AL9-T6?
AL9-T6. Its machinability rates good (60/100) against fair (52/100) for AL9-T4.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AL9-T4 and AL9-T6 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.