Steel 9CrSi vs A11
Steel · grade comparison
Steel 9CrSi and A11 are both steel grades, both tool steel. A11 is the stronger of the two: yield strength 600 MPa (87 ksi) against 430 MPa (62.4 ksi) for 9CrSi, about 40% more; tensile strength follows at 900 MPa (131 ksi) vs 750 MPa (109 ksi). In exchange, 9CrSi is the more ductile: elongation 15% versus 8% for A11, and A11 is harder (269 HB vs 217 HB). A11 is lighter (7.41 g/cm³ vs 7.77 g/cm³ for 9CrSi) and A11 runs hotter in service (425°C vs 300°C continuous). On the shop floor, 9CrSi machines more easily (fair vs poor) and 9CrSi sits in a lower cost tier (premium, $$$) than A11 (specialty, $$$$$).
9CrSiChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
A11Choose it when strength drives the design, or when weight is the constraint.
9CrSi vs A11: 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
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Fracture Toughness (K_IC)
Hardness, Rockwell C
Same in both: 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)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
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
Polishability
Same in both: Weldability 15 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | 9CrSi | A11 |
|---|---|---|
| Default condition | Annealed | Annealed |
| Relative cost | $$$ Premium | $$$$$ Specialty |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
9CrSi vs A11 — frequently asked
Is A11 stronger than 9CrSi?
Yes. A11 has a typical yield strength of 600 MPa (87 ksi) against 430 MPa (62.4 ksi) for 9CrSi — about 40% more. Tensile strength is 900 MPa (131 ksi) vs 750 MPa (109 ksi).
Which is cheaper, 9CrSi or A11?
9CrSi is the lower-cost material: it sits in the premium tier ($$$) while A11 is specialty ($$$$$). 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, 9CrSi or A11?
9CrSi. Its machinability rates fair (50/100) against poor (20/100) for A11.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 9CrSi and A11 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.