Steel A8 vs O1
Steel · grade comparison
Steel A8 and O1 are both steel grades, both tool steel. A8 is the stronger of the two: yield strength 500 MPa (72.5 ksi) against 400 MPa (58 ksi) for O1, about 25% more; tensile strength follows at 780 MPa (113 ksi) vs 690 MPa (100 ksi). In exchange, O1 is the more ductile: elongation 25% versus 18% for A8, and A8 is harder (220 HB vs 200 HB). O1 runs hotter in service (400°C vs 200°C continuous) and O1 conducts heat better (35 W/m·K vs 24.5 W/m·K). On the shop floor, A8 sits in a lower cost tier (premium, $$$) than O1 (high, $$$$).
A8Choose it when strength drives the design, or when cost is the deciding factor.
O1Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
A8 vs O1: 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
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Fatigue Strength (Endurance Limit)
Hardness, Rockwell B
Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
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 Rating (AISI 1212 = 100 %)
Formability (cold)
Brazeability / Solderability
Polishability
Same in both: Machinability 45 / 100 · Weldability 20 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 40%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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 | A8 | O1 |
|---|---|---|
| Default condition | Annealed | Annealed |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
A8 vs O1 — frequently asked
Is A8 stronger than O1?
Yes. A8 has a typical yield strength of 500 MPa (72.5 ksi) against 400 MPa (58 ksi) for O1 — about 25% more. Tensile strength is 780 MPa (113 ksi) vs 690 MPa (100 ksi).
Which is cheaper, A8 or O1?
A8 is the lower-cost material: it sits in the premium tier ($$$) while O1 is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose A8 over O1?
Pick A8 when strength drives the design, or when cost is the deciding factor. Pick O1 when the part is bent, formed or impact-loaded, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in A8 and O1 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.