Aluminum 6351-T4 vs 6351-T6
Aluminum · 6351 temper comparison
6351-T4 and 6351-T6 are two conditions of the same aluminum grade, 6351: 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. 6351-T6 is the stronger of the two: yield strength 285 MPa (41.3 ksi) against 150 MPa (21.8 ksi) for 6351-T4, about 90% more; tensile strength follows at 310 MPa (45 ksi) vs 250 MPa (36.3 ksi). In exchange, 6351-T4 is the more ductile: elongation 20% versus 14% for 6351-T6, and 6351-T6 is harder (95 HB vs 65 HB). 6351-T6 runs hotter in service (150°C vs 100°C continuous) and 6351-T6 conducts heat better (176 W/m·K vs 154 W/m·K). On the shop floor, 6351-T6 machines more easily (good vs fair).
6351-T4Choose it when the part is bent, formed or impact-loaded.
6351-T6Choose it when strength drives the design, or when the part sees heat.
6351-T4 vs 6351-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)
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) 29 MPa·√m26.4 ksi·√in · Hardness, Vickers 105 HV
Physical
Density and transition temperatures.
Same in both: Density 2.71 g/cm³0.1 lb/in³ · Melting Point (Solidus) 555°C1,031 °F · Liquidus Temperature 650°C1,202 °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) 23.4 µm/m·K13 µin/in·°F · Latent Heat of Fusion 390 J/g168 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) -0.74 V · Corrosion Resistance 62 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 190% · Weldability 78 / 100 · Castability 30 / 100 · Brazeability / Solderability 45 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 210 MJ/kg90,284 BTU/lb · Embodied Carbon (primary production) 12.5 kg CO₂/kg · Embodied Water 1,150 L/kg138 gal/lb · Typical Recycled Content 30%
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.
6351-T4 vs 6351-T6 — frequently asked
Is 6351-T6 stronger than 6351-T4?
Yes. 6351-T6 has a typical yield strength of 285 MPa (41.3 ksi) against 150 MPa (21.8 ksi) for 6351-T4 — about 90% more. Tensile strength is 310 MPa (45 ksi) vs 250 MPa (36.3 ksi).
Which condition does FabDigit quote by default, T4 or T6?
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, 6351-T4 or 6351-T6?
6351-T6. Its machinability rates good (62/100) against fair (48/100) for 6351-T4.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6351-T4 and 6351-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.