Aluminum 2618-O vs 2618-T651
Aluminum · 2618 temper comparison
2618-O and 2618-T651 are two conditions of the same aluminum grade, 2618: O (annealed) versus T651 (T6, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. 2618-T651 is the stronger of the two: yield strength 375 MPa (54.4 ksi) against 125 MPa (18.1 ksi) for 2618-O, about 3.0 times as much; tensile strength follows at 440 MPa (63.8 ksi) vs 215 MPa (31.2 ksi). In exchange, 2618-O is the more ductile: elongation 18% versus 9% for 2618-T651, and 2618-T651 is harder (118 HB vs 65 HB). 2618-T651 runs hotter in service (200°C vs 150°C continuous). On the shop floor, 2618-T651 machines more easily (good vs fair).
2618-OChoose it when the part is bent, formed or impact-loaded.
2618-T651Choose it when strength drives the design, or when the part sees heat.
2618-O vs 2618-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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 74.5 GPa10.8 Msi · Shear Modulus 28 GPa4.1 Msi · Bulk Modulus 76 GPa11 Msi · Poisson's Ratio 0.33 · Reduction in Area 20% · Fracture Toughness (K_IC) 28 MPa·√m25.5 ksi·√in
Physical
Density and transition temperatures.
Same in both: Density 2.76 g/cm³0.1 lb/in³ · Melting Point (Solidus) 549°C1,020 °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 389 J/g167 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 4.66×10⁻⁸ Ω·m1.83 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.7 V · Corrosion Resistance 32 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 22 / 100 · Castability 20 / 100 · Brazeability / Solderability 15 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 205 MJ/kg88,134 BTU/lb · Embodied Carbon (primary production) 12.5 kg CO₂/kg · Embodied Water 1,150 L/kg138 gal/lb · Typical Recycled Content 5%
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.
2618-O vs 2618-T651 — frequently asked
Is 2618-T651 stronger than 2618-O?
Yes. 2618-T651 has a typical yield strength of 375 MPa (54.4 ksi) against 125 MPa (18.1 ksi) for 2618-O — about 3.0 times as much. Tensile strength is 440 MPa (63.8 ksi) vs 215 MPa (31.2 ksi).
Which condition does FabDigit quote by default, O or T651?
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, 2618-O or 2618-T651?
2618-T651. Its machinability rates good (68/100) against fair (40/100) for 2618-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 2618-O and 2618-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.