Steel O1 vs O7
Steel · grade comparison
Steel O1 and O7 are both steel grades. Both yield at about 400 MPa — strength does not separate them. O1 runs hotter in service (400°C vs 200°C continuous) and O1 conducts electricity better (7 % IACS vs 3 % IACS). On the shop floor, O7 machines more easily (good vs fair), O1 forms better (fair vs poor), and O7 sits in a lower cost tier (premium, $$$) than O1 (high, $$$$).
O1Choose it when the part sees heat.
O7Choose it when the part is machined in volume, or when cost is the deciding factor.
O1 vs O7: 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.
Shear Modulus
Elongation at Break
Shear Strength
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Tensile Strength (Ultimate) 690 MPa100 ksi · Yield Strength (0.2% offset) 400 MPa58 ksi · Reduction in Area 45% · Compressive Strength 420 MPa60.9 ksi · Fatigue Strength (Endurance Limit) 320 MPa46.4 ksi · Hardness, Rockwell B 94 HRB
Physical
Density and transition temperatures.
Density
Liquidus Temperature
Same in both: Melting Point (Solidus) 1,400°C2,552 °F
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).
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
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Brazeability / Solderability
Polishability
Castability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 2.4 kg CO₂/kg
Common Calculations
Ratios derived from the values above.
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: Specific Strength (UTS / density) 88 kN·m/kg · Modulus of Resilience 390 kJ/m³ · Thermal Shock Resistance Index 10
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 | O1 | O7 |
|---|---|---|
| CNC machining | Yes | — |
| Default condition | Annealed | — |
| Relative cost | $$$$ High | $$$ Premium |
| Min. machined wall | 0.8 mm | — |
| Best machined surface | Ra 1.6 µm | — |
| AlCrN | Yes | — |
| AlTiN | Yes | — |
| Black Oxide | Yes | — |
| CVD Al2O3 | Yes | — |
| CVD TiCN | Yes | — |
| CVD TiN | Yes | — |
| Cerakote | Yes | — |
| Chrome Plating | Yes | — |
| CrN | Yes | — |
| DLC | Yes | — |
| E-Coating | Yes | — |
| HVOF Coating | Yes | — |
| Hot-Dip Galvanizing | Yes | — |
| MoS2 | Yes | — |
| Multilayer CVD | Yes | — |
| Nickel Plating | Yes | — |
| PTFE Coating | Yes | — |
| Painting | Yes | — |
They share 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
O1 vs O7 — frequently asked
What is the difference between O1 and O7?
Steel O1 and O7 are both steel grades. Both yield at about 400 MPa — strength does not separate them. O1 runs hotter in service (400°C vs 200°C continuous) and O1 conducts electricity better (7 % IACS vs 3 % IACS).
Which is cheaper, O1 or O7?
O7 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.
Which is easier to machine, O1 or O7?
O7. Its machinability rates good (55/100) against fair (45/100) for O1; for welding the order is O1 first (poor, 20/100) then O7 (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in O1 and O7 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.