Aluminum 7178-O vs 7178-T7651
Aluminum · 7178 temper comparison
7178-O and 7178-T7651 are two conditions of the same aluminum grade, 7178: O (annealed) versus T7651 (T76, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. 7178-T7651 is the stronger of the two: yield strength 510 MPa (74 ksi) against 103 MPa (14.9 ksi) for 7178-O, about 5.0 times as much; tensile strength follows at 572 MPa (83 ksi) vs 228 MPa (33.1 ksi). In exchange, 7178-O is the more ductile: elongation 15% versus 10% for 7178-T7651, and 7178-T7651 is harder (150 HB vs 60 HB). 7178-O runs hotter in service (200°C vs 150°C continuous). On the shop floor, 7178-T7651 machines more easily (very good vs fair).
7178-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
7178-T7651Choose it when strength drives the design, or when the part is machined in volume.
7178-O vs 7178-T7651: 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 71.7 GPa10.4 Msi · Shear Modulus 26.9 GPa3.9 Msi · Bulk Modulus 70 GPa10.2 Msi · Poisson's Ratio 0.33
Physical
Density and transition temperatures.
Same in both: Density 2.83 g/cm³0.1 lb/in³ · Melting Point (Solidus) 477°C891 °F · Liquidus Temperature 629°C1,164 °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 860 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 Resistivity
Same in both: Electrical Conductivity 38 % IACS
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.83 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 12 / 100 · Brazeability / Solderability 10 / 100 · Polishability 60 / 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 15%
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.
7178-O vs 7178-T7651 — frequently asked
Is 7178-T7651 stronger than 7178-O?
Yes. 7178-T7651 has a typical yield strength of 510 MPa (74 ksi) against 103 MPa (14.9 ksi) for 7178-O — about 5.0 times as much. Tensile strength is 572 MPa (83 ksi) vs 228 MPa (33.1 ksi).
Which condition does FabDigit quote by default, O or T7651?
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, 7178-O or 7178-T7651?
7178-T7651. Its machinability rates very good (75/100) against fair (45/100) for 7178-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 7178-O and 7178-T7651 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.