Steel 18CrNiMo7-6 vs 42CrMo4
Steel · grade comparison
Steel 18CrNiMo7-6 and 42CrMo4 are both steel grades. 42CrMo4 is the stronger of the two: yield strength 550 MPa (79.8 ksi) against 370 MPa (53.7 ksi) for 18CrNiMo7-6, about 49% more; tensile strength follows at 850 MPa (123 ksi) vs 640 MPa (92.8 ksi). In exchange, 18CrNiMo7-6 is the more ductile: elongation 20% versus 14% for 42CrMo4, and 42CrMo4 is harder (245 HB vs 200 HB). 42CrMo4 runs hotter in service (400°C vs 350°C continuous). On the shop floor, 18CrNiMo7-6 welds better (45 vs 35 out of 100).
18CrNiMo7-6Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
42CrMo4Choose it when strength drives the design, or when the part sees heat.
18CrNiMo7-6 vs 42CrMo4: 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
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Compressive Strength
Hardness, Rockwell C
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Melting Point (Solidus)
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Liquidus Temperature 1,495°C2,723 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Same in both: Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 55%
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)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 26.8 MN·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 | 18CrNiMo7-6 | 42CrMo4 |
|---|---|---|
| Default condition | Annealed | HR |
| Relative cost | $$ Standard | $$ Standard |
| 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 and Sheet metal. 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.
18CrNiMo7-6 vs 42CrMo4 — frequently asked
Is 42CrMo4 stronger than 18CrNiMo7-6?
Yes. 42CrMo4 has a typical yield strength of 550 MPa (79.8 ksi) against 370 MPa (53.7 ksi) for 18CrNiMo7-6 — about 49% more. Tensile strength is 850 MPa (123 ksi) vs 640 MPa (92.8 ksi).
Which is cheaper, 18CrNiMo7-6 or 42CrMo4?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, 18CrNiMo7-6 or 42CrMo4?
18CrNiMo7-6. Its machinability rates good (55/100) against fair (50/100) for 42CrMo4; for welding the order is 18CrNiMo7-6 first (fair, 45/100) then 42CrMo4 (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18CrNiMo7-6 and 42CrMo4 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.