Aluminum 355-T51 vs 355-T6
Aluminum · 355 temper comparison
355-T51 and 355-T6 are two conditions of the same aluminum grade, 355: T51 (T5, stress relieved by stretching) versus T6 (solution heat treated and artificially aged). The chemistry is identical, so every difference below comes from the condition. 355-T6 is the stronger of the two: yield strength 180 MPa (26.1 ksi) against 165 MPa (23.9 ksi) for 355-T51, about 9% more; tensile strength follows at 250 MPa (36.3 ksi) vs 200 MPa (29 ksi). 355-T6 is the more ductile: elongation 3% versus 1.8% for 355-T51, and 355-T6 is harder (85 HB vs 70 HB). 355-T51 runs hotter in service (200°C vs 175°C continuous) and 355-T51 conducts electricity better (43 % IACS vs 36 % IACS).
355-T51Choose it when the part sees heat.
355-T6Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
355-T51 vs 355-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 71 GPa10.3 Msi · Shear Modulus 26.5 GPa3.8 Msi · Bulk Modulus 69 GPa10 Msi · Poisson's Ratio 0.33 · Fracture Toughness (K_IC) 20 MPa·√m18.2 ksi·√in
Physical
Density and transition temperatures.
Same in both: Density 2.71 g/cm³0.1 lb/in³ · Melting Point (Solidus) 546°C1,015 °F · Liquidus Temperature 621°C1,150 °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 963 J/kg·K0.23 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 22.4 µm/m·K12.4 µin/in·°F · Latent Heat of Fusion 389 J/g167 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 4.8×10⁻⁸ Ω·m1.89 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.78 V · Corrosion Resistance 45 / 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 55 / 100 · Formability (cold) 5 / 100 · Castability 85 / 100 · Brazeability / Solderability 25 / 100 · Polishability 45 / 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 1,100 L/kg132 gal/lb · Typical Recycled Content 80%
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.
355-T51 vs 355-T6 — frequently asked
Is 355-T6 stronger than 355-T51?
Yes. 355-T6 has a typical yield strength of 180 MPa (26.1 ksi) against 165 MPa (23.9 ksi) for 355-T51 — about 9% more. Tensile strength is 250 MPa (36.3 ksi) vs 200 MPa (29 ksi).
Which condition does FabDigit quote by default, T51 or T6?
Specify the condition in the material field or the drawing note; FabDigit prices the quote for the state you call out.
When should I choose 355-T51 over 355-T6?
Pick 355-T51 when the part sees heat. Pick 355-T6 when strength drives the design, or when the part is bent, formed or impact-loaded.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 355-T51 and 355-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.