Aluminum 6018-O vs 6018-T4
Aluminum · 6018 temper comparison
6018-O and 6018-T4 are two conditions of the same aluminum grade, 6018: O (annealed) versus T4 (solution heat treated and naturally aged). The chemistry is identical, so every difference below comes from the condition. 6018-T4 is the stronger of the two: yield strength 130 MPa (18.9 ksi) against 65 MPa (9.43 ksi) for 6018-O, about 100% more; tensile strength follows at 235 MPa (34.1 ksi) vs 130 MPa (18.9 ksi). In exchange, 6018-O is the more ductile: elongation 22% versus 18% for 6018-T4, and 6018-T4 is harder (65 HB vs 35 HB). 6018-O runs hotter in service (200°C vs 150°C continuous) and 6018-O conducts heat better (195 W/m·K vs 155 W/m·K). On the shop floor, 6018-T4 machines more easily (82 vs 70 out of 100).
6018-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
6018-T4Choose it when strength drives the design, or when the part is machined in volume.
6018-O vs 6018-T4: 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 68 GPa9.9 Msi · Poisson's Ratio 0.33 · Reduction in Area 30% · Compressive Strength 295 MPa42.8 ksi · Fracture Toughness (K_IC) 29 MPa·√m26.4 ksi·√in · Charpy V-Notch Impact (RT) 12 J8.9 ft·lbf · Hardness, Rockwell B 60 HRB · Hardness, Vickers 100 HV
Physical
Density and transition temperatures.
Same in both: Density 2.71 g/cm³0.1 lb/in³ · Melting Point (Solidus) 585°C1,085 °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
Same in both: Electrical Resistivity 4.1×10⁻⁸ Ω·m1.61 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.74 V · Corrosion Resistance 58 / 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 %) 300% · Weldability 35 / 100 · Castability 30 / 100 · Brazeability / Solderability 30 / 100 · Polishability 60 / 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 1,100 L/kg132 gal/lb · Typical Recycled Content 25%
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.
6018-O vs 6018-T4 — frequently asked
Is 6018-T4 stronger than 6018-O?
Yes. 6018-T4 has a typical yield strength of 130 MPa (18.9 ksi) against 65 MPa (9.43 ksi) for 6018-O — about 100% more. Tensile strength is 235 MPa (34.1 ksi) vs 130 MPa (18.9 ksi).
Which condition does FabDigit quote by default, O or T4?
T6 is the default 6018 condition in the FabDigit quote flow (neither O nor T4). 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, 6018-O or 6018-T4?
6018-T4, by a small margin. Both rate very good for machinability — 82/100 against 70/100 for 6018-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 6018-O and 6018-T4 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.