Steel O2 Annealed vs O2 Hardened & Tempered
Steel · O2 temper comparison
O2 Annealed and O2 Hardened & Tempered are two conditions of the same steel grade, O2: Annealed versus Hardened & Tempered (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. O2 Hardened & Tempered is the stronger of the two: yield strength 1,900 MPa (276 ksi) against 420 MPa (60.9 ksi) for O2 Annealed, about 4.5 times as much; tensile strength follows at 2,200 MPa (319 ksi) vs 740 MPa (107 ksi). In exchange, O2 Annealed is the more ductile: elongation 25% versus 1% for O2 Hardened & Tempered, and O2 Hardened & Tempered is harder (740 HV vs 215 HV). O2 Annealed runs hotter in service (300°C vs 180°C continuous). On the shop floor, O2 Annealed machines more easily (fair vs not recommended).
O2 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
O2 Hardened & TemperedChoose it when strength drives the design.
O2 Annealed vs O2 Hardened & Tempered: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel 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 steel 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.
O2 AnnealedO2 Hardened & Tempered
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)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 50% · Hardness, Brinell 205 HB · Hardness, Rockwell B 94 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,460°C2,660 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 33 W/m·K19.1 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.5 µm/m·K6.9 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 45% · Weldability 15 / 100 · Formability (cold) 40 / 100 · Brazeability / Solderability 35 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 35%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
O2 Annealed vs O2 Hardened & Tempered — frequently asked
Is O2 Hardened & Tempered stronger than O2 Annealed?
Yes. O2 Hardened & Tempered has a typical yield strength of 1,900 MPa (276 ksi) against 420 MPa (60.9 ksi) for O2 Annealed — about 4.5 times as much. Tensile strength is 2,200 MPa (319 ksi) vs 740 MPa (107 ksi).
Which condition does FabDigit quote by default, Annealed or Hardened & Tempered?
Annealed is the default O2 condition in the FabDigit quote flow. 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, O2 Annealed or O2 Hardened & Tempered?
O2 Annealed. Its machinability rates fair (48/100) against not recommended (5/100) for O2 Hardened & Tempered.
Ready to make it?
Upload a CAD file and FabDigit prices the part in O2 Annealed and O2 Hardened & Tempered 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.