Aluminum 2199-O vs 2199-T851
Aluminum · 2199 temper comparison
2199-O and 2199-T851 are two conditions of the same aluminum grade, 2199: O (annealed) versus T851 (T8, stress relieved by stretching). The chemistry is identical, so every difference below comes from the condition. 2199-T851 is the stronger of the two: yield strength 420 MPa (60.9 ksi) against 135 MPa (19.6 ksi) for 2199-O, about 3.1 times as much; tensile strength follows at 470 MPa (68.2 ksi) vs 250 MPa (36.3 ksi). In exchange, 2199-O is the more ductile: elongation 20% versus 9% for 2199-T851, and 2199-T851 is harder (136 HB vs 65 HB). 2199-O conducts heat better (120 W/m·K vs 90 W/m·K). On the shop floor, 2199-T851 machines more easily (good vs fair).
2199-OChoose it when the part is bent, formed or impact-loaded.
2199-T851Choose it when strength drives the design, or when the part is machined in volume.
2199-O vs 2199-T851: 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)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 78 GPa11.3 Msi · Shear Modulus 29.5 GPa4.3 Msi · Bulk Modulus 76 GPa11 Msi · Poisson's Ratio 0.33
Physical
Density and transition temperatures.
Same in both: Density 2.63 g/cm³0.1 lb/in³ · Melting Point (Solidus) 545°C1,013 °F · Liquidus Temperature 650°C1,202 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Same in both: Specific Heat Capacity 900 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 390 J/g168 BTU/lb · Max Service Temperature (continuous) 120°C248 °F · Min Service Temperature -253°C-423 °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) -0.72 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Castability 25 / 100 · Brazeability / Solderability 15 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 230 MJ/kg98,882 BTU/lb · Embodied Carbon (primary production) 14 kg CO₂/kg · Embodied Water 1,200 L/kg144 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.
2199-O vs 2199-T851 — frequently asked
Is 2199-T851 stronger than 2199-O?
Yes. 2199-T851 has a typical yield strength of 420 MPa (60.9 ksi) against 135 MPa (19.6 ksi) for 2199-O — about 3.1 times as much. Tensile strength is 470 MPa (68.2 ksi) vs 250 MPa (36.3 ksi).
Which condition does FabDigit quote by default, O or T851?
T8E74 is the default 2199 condition in the FabDigit quote flow (neither O nor T851). 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, 2199-O or 2199-T851?
2199-T851. Its machinability rates good (57/100) against fair (40/100) for 2199-O; for welding the order is 2199-O first (fair, 35/100) then 2199-T851 (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 2199-O and 2199-T851 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.