Steel A2 vs O2
Steel · grade comparison
Steel A2 and O2 are both steel grades, both tool steel. A2 is the stronger of the two: yield strength 470 MPa (68.2 ksi) against 420 MPa (60.9 ksi) for O2, about 12% more. In exchange, O2 is the more ductile: elongation 25% versus 22% for A2, and A2 is harder (217 HB vs 205 HB). A2 runs hotter in service (425°C vs 300°C continuous) and O2 conducts heat better (33 W/m·K vs 26 W/m·K).
A2Choose it when strength drives the design, or when the part sees heat.
O2Choose it when the part is bent, formed or impact-loaded.
A2 vs O2: 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.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Poisson's Ratio
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Tensile Strength (Ultimate) 740 MPa107 ksi · Shear Strength 450 MPa65.3 ksi
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Galvanic Potential (seawater, vs SCE)
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Same in both: Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 35%
Common Calculations
Ratios derived from the values above.
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Specific Strength (UTS / density) 94 kN·m/kg · Thermal Shock Resistance Index 9
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.
Manufacturing and finishing
| Capability | A2 | O2 |
|---|---|---|
| Default condition | Annealed | Annealed |
| Relative cost | $$$ Premium | $$$ Premium |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
A2 vs O2 — frequently asked
Is A2 stronger than O2?
Yes. A2 has a typical yield strength of 470 MPa (68.2 ksi) against 420 MPa (60.9 ksi) for O2 — about 12% more. Tensile strength is 740 MPa (107 ksi) vs 740 MPa (107 ksi).
Which is cheaper, A2 or O2?
Both sit in the same relative cost tier ($$$, premium); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which welds better, A2 or O2?
A2. Its weldability rates poor (20/100) against poor (15/100) for O2.
Ready to make it?
Upload a CAD file and FabDigit prices the part in A2 and O2 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.