Steel 9CrSi vs A3
Steel · grade comparison
Steel 9CrSi and A3 are both steel grades, both tool steel. Both yield at about 430 MPa — strength does not separate them. A3 is the more ductile: elongation 20% versus 15% for 9CrSi. 9CrSi runs hotter in service (300°C vs 200°C continuous) and 9CrSi conducts heat better (34 W/m·K vs 24 W/m·K). On the shop floor, 9CrSi machines more easily (50 vs 38 out of 100).
9CrSiChoose it when the part sees heat, or when the part is machined in volume.
A3Choose it when the part is bent, formed or impact-loaded.
9CrSi vs A3: 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)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Rockwell C
Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 430 MPa62.4 ksi · Compressive Strength 900 MPa131 ksi · Charpy V-Notch Impact (RT) 25 J18.4 ft·lbf · Hardness, Brinell 217 HB · Hardness, Rockwell B 96 HRB · Hardness, Vickers 228 HV
Physical
Density and transition temperatures.
Density
Liquidus Temperature
Same in both: Melting Point (Solidus) 1,420°C2,588 °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)
Min Service Temperature
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Latent Heat of Fusion 250 J/g107 BTU/lb
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) -0.6 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Castability
Brazeability / Solderability
Same in both: Weldability 15 / 100 · 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 30%
Common Calculations
Ratios derived from the values above.
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Strength (UTS / density) 97 kN·m/kg
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 | 9CrSi | A3 |
|---|---|---|
| Default condition | 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.
9CrSi vs A3 — frequently asked
What is the difference between 9CrSi and A3?
Steel 9CrSi and A3 are both steel grades, both tool steel. Both yield at about 430 MPa — strength does not separate them. A3 is the more ductile: elongation 20% versus 15% for 9CrSi.
Which is cheaper, 9CrSi or A3?
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 is easier to machine, 9CrSi or A3?
9CrSi, by a small margin. Both rate fair for machinability — 50/100 against 38/100 for A3.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 9CrSi and A3 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.