Steel 40CrNiMoA vs HP9-4-20
Steel · grade comparison
Steel 40CrNiMoA and HP9-4-20 are both steel grades. HP9-4-20 is the stronger of the two: yield strength 1,210 MPa (175 ksi) against 950 MPa (138 ksi) for 40CrNiMoA, about 27% more; tensile strength follows at 1,340 MPa (194 ksi) vs 1,080 MPa (157 ksi). HP9-4-20 is harder — 390 HB against 320 HB for 40CrNiMoA — which matters for wear surfaces and threads. 40CrNiMoA conducts heat better (44 W/m·K vs 30 W/m·K). On the shop floor, 40CrNiMoA machines more easily (fair vs poor), HP9-4-20 welds better (very good vs poor), and 40CrNiMoA sits in a lower cost tier (standard, $$) than HP9-4-20 (high, $$$$).
40CrNiMoAChoose it when the part is machined in volume, or when cost is the deciding factor.
HP9-4-20Choose it when strength drives the design, or when surface hardness matters.
40CrNiMoA vs HP9-4-20: 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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
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
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Min Service Temperature
Same in both: Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 400°C752 °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 15 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Castability
Brazeability / Solderability
Polishability
Same in both: Formability (cold) 25 / 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 | 40CrNiMoA | HP9-4-20 |
|---|---|---|
| CNC machining | Yes | — |
| Sheet metal | Yes | — |
| Default condition | Q&T | — |
| Relative cost | $$ Standard | $$$$ High |
| Min. machined wall | 0.8 mm | — |
| Best machined surface | Ra 1.6 µm | — |
| AlCrN | Yes | — |
| AlTiN | Yes | — |
| Black Oxide | Yes | — |
| CVD Al2O3 | Yes | — |
| CVD TiCN | Yes | — |
| CVD TiN | Yes | — |
| Cerakote | Yes | — |
| Chrome Plating | Yes | — |
| CrN | Yes | — |
| DLC | Yes | — |
| E-Coating | Yes | — |
| HVOF Coating | Yes | — |
| Hot-Dip Galvanizing | Yes | — |
| MoS2 | Yes | — |
| Multilayer CVD | Yes | — |
| Nickel Plating | Yes | — |
| PTFE Coating | Yes | — |
| Painting | Yes | — |
They share 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
40CrNiMoA vs HP9-4-20 — frequently asked
Is HP9-4-20 stronger than 40CrNiMoA?
Yes. HP9-4-20 has a typical yield strength of 1,210 MPa (175 ksi) against 950 MPa (138 ksi) for 40CrNiMoA — about 27% more. Tensile strength is 1,340 MPa (194 ksi) vs 1,080 MPa (157 ksi).
Which is cheaper, 40CrNiMoA or HP9-4-20?
40CrNiMoA is the lower-cost material: it sits in the standard tier ($$) while HP9-4-20 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, 40CrNiMoA or HP9-4-20?
40CrNiMoA. Its machinability rates fair (42/100) against poor (28/100) for HP9-4-20; for welding the order is HP9-4-20 first (very good, 70/100) then 40CrNiMoA (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 40CrNiMoA and HP9-4-20 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.