Aluminum 7039-O vs 7039-T61
Aluminum · 7039 temper comparison
7039-O and 7039-T61 are two conditions of the same aluminum grade, 7039: O (annealed) versus T61 (T6 variant, underaged). The chemistry is identical, so every difference below comes from the condition. 7039-T61 is the stronger of the two: yield strength 345 MPa (50 ksi) against 115 MPa (16.7 ksi) for 7039-O, about 3.0 times as much; tensile strength follows at 415 MPa (60.2 ksi) vs 235 MPa (34.1 ksi). In exchange, 7039-O is the more ductile: elongation 20% versus 13% for 7039-T61, and 7039-T61 is harder (122 HB vs 65 HB). 7039-O conducts electricity better (40 % IACS vs 36 % IACS). On the shop floor, 7039-T61 machines more easily (good vs fair).
7039-OChoose it when the part is bent, formed or impact-loaded.
7039-T61Choose it when strength drives the design, or when the part is machined in volume.
7039-O vs 7039-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
Same in both: Elastic (Young's) Modulus 69.6 GPa10.1 Msi · Shear Modulus 26.2 GPa3.8 Msi · Bulk Modulus 69 GPa10 Msi · Poisson's Ratio 0.33
Physical
Density and transition temperatures.
Same in both: Density 2.74 g/cm³0.1 lb/in³ · Melting Point (Solidus) 585°C1,085 °F · Liquidus Temperature 640°C1,184 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Same in both: Specific Heat Capacity 960 J/kg·K0.23 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 · Max Service Temperature (continuous) 120°C248 °F · 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) -0.84 V
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 75 / 100 · Castability 25 / 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 1,200 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.
7039-O vs 7039-T61 — frequently asked
Is 7039-T61 stronger than 7039-O?
Yes. 7039-T61 has a typical yield strength of 345 MPa (50 ksi) against 115 MPa (16.7 ksi) for 7039-O — about 3.0 times as much. Tensile strength is 415 MPa (60.2 ksi) vs 235 MPa (34.1 ksi).
Which condition does FabDigit quote by default, O or T61?
T6 is the default 7039 condition in the FabDigit quote flow (neither O nor T61). 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, 7039-O or 7039-T61?
7039-T61. Its machinability rates good (68/100) against fair (45/100) for 7039-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 7039-O and 7039-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.