Aluminum 2018-T4 vs 2018-T61
Aluminum · 2018 temper comparison
2018-T4 and 2018-T61 are two conditions of the same aluminum grade, 2018: T4 (solution heat treated and naturally aged) versus T61 (T6 variant, underaged). The chemistry is identical, so every difference below comes from the condition. 2018-T61 is the stronger of the two: yield strength 315 MPa (45.7 ksi) against 205 MPa (29.7 ksi) for 2018-T4, about 54% more; tensile strength follows at 420 MPa (60.9 ksi) vs 350 MPa (50.8 ksi). In exchange, 2018-T4 is the more ductile: elongation 18% versus 12% for 2018-T61, and 2018-T61 is harder (120 HB vs 95 HB). 2018-T61 runs hotter in service (200°C vs 100°C continuous) and 2018-T61 conducts heat better (154 W/m·K vs 134 W/m·K). On the shop floor, 2018-T61 machines more easily (very good vs good).
2018-T4Choose it when the part is bent, formed or impact-loaded.
2018-T61Choose it when strength drives the design, or when the part sees heat.
2018-T4 vs 2018-T61: 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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 74 GPa10.7 Msi · Shear Modulus 28 GPa4.1 Msi · Bulk Modulus 76 GPa11 Msi · Poisson's Ratio 0.33
Physical
Density and transition temperatures.
Same in both: Density 2.8 g/cm³0.1 lb/in³ · Melting Point (Solidus) 507°C945 °F · Liquidus Temperature 638°C1,180 °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 875 J/kg·K0.21 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 22.3 µm/m·K12.4 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.7 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Same in both: Weldability 22 / 100 · Brazeability / Solderability 15 / 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) 12.5 kg CO₂/kg · Embodied Water 1,200 L/kg144 gal/lb · Typical Recycled Content 20%
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.
2018-T4 vs 2018-T61 — frequently asked
Is 2018-T61 stronger than 2018-T4?
Yes. 2018-T61 has a typical yield strength of 315 MPa (45.7 ksi) against 205 MPa (29.7 ksi) for 2018-T4 — about 54% more. Tensile strength is 420 MPa (60.9 ksi) vs 350 MPa (50.8 ksi).
Which condition does FabDigit quote by default, T4 or T61?
T61 is the default 2018 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, 2018-T4 or 2018-T61?
2018-T61. Its machinability rates very good (72/100) against good (62/100) for 2018-T4.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 2018-T4 and 2018-T61 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.