Aluminum 5251-H34 vs 5251-O
Aluminum · 5251 temper comparison
5251-H34 and 5251-O are two conditions of the same aluminum grade, 5251: H34 (strain hardened and stabilized, half hard) versus O (annealed). The chemistry is identical, so every difference below comes from the condition. 5251-H34 is the stronger of the two: yield strength 180 MPa (26.1 ksi) against 75 MPa (10.9 ksi) for 5251-O, about 140% more; tensile strength follows at 230 MPa (33.4 ksi) vs 180 MPa (26.1 ksi). In exchange, 5251-O is the more ductile: elongation 23% versus 8% for 5251-H34, and 5251-H34 is harder (65 HB vs 45 HB). 5251-O runs hotter in service (150°C vs 120°C continuous). On the shop floor, 5251-H34 machines more easily (50 vs 35 out of 100).
5251-H34Choose it when strength drives the design, or when the part is machined in volume.
5251-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
5251-H34 vs 5251-O: 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 70 GPa10.2 Msi · Shear Modulus 26 GPa3.8 Msi · Bulk Modulus 70 GPa10.2 Msi · Poisson's Ratio 0.33
Physical
Density and transition temperatures.
Same in both: Density 2.69 g/cm³0.1 lb/in³ · Melting Point (Solidus) 607°C1,125 °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 900 J/kg·K0.21 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 23.8 µm/m·K13.2 µin/in·°F · Latent Heat of Fusion 395 J/g170 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 5.1×10⁻⁸ Ω·m2.01 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.86 V · Corrosion Resistance 72 / 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 88 / 100 · Brazeability / Solderability 25 / 100 · Polishability 55 / 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 30%
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.
5251-H34 vs 5251-O — frequently asked
Is 5251-H34 stronger than 5251-O?
Yes. 5251-H34 has a typical yield strength of 180 MPa (26.1 ksi) against 75 MPa (10.9 ksi) for 5251-O — about 140% more. Tensile strength is 230 MPa (33.4 ksi) vs 180 MPa (26.1 ksi).
Which condition does FabDigit quote by default, H34 or O?
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, 5251-H34 or 5251-O?
5251-H34, by a small margin. Both rate fair for machinability — 50/100 against 35/100 for 5251-O.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 5251-H34 and 5251-O 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.