Steel 55Cr3 vs 8MoB5-4
Steel · grade comparison
Steel 55Cr3 and 8MoB5-4 are both steel grades. 55Cr3 is the stronger of the two: yield strength 480 MPa (69.6 ksi) against 255 MPa (37 ksi) for 8MoB5-4, about 88% more; tensile strength follows at 800 MPa (116 ksi) vs 410 MPa (59.5 ksi). In exchange, 8MoB5-4 is the more ductile: elongation 30% versus 16% for 55Cr3, and 55Cr3 is harder (225 HB vs 135 HB). On the shop floor, 8MoB5-4 welds better (very good vs poor) and 8MoB5-4 sits in a lower cost tier (budget, $) than 55Cr3 (standard, $$).
55Cr3Choose it when strength drives the design.
8MoB5-4Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
55Cr3 vs 8MoB5-4: 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 B
Hardness, Rockwell C
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Melting Point (Solidus)
Liquidus Temperature
Same in both: Density 7.85 g/cm³0.28 lb/in³
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Same in both: Thermal Conductivity 44 W/m·K25.4 BTU/hr·ft·°F · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Galvanic Potential (seawater, vs SCE)
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
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 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 | 55Cr3 | 8MoB5-4 |
|---|---|---|
| CNC machining | Yes | — |
| Sheet metal | Yes | — |
| Default condition | Annealed | — |
| Relative cost | $$ Standard | $ Budget |
| 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.
55Cr3 vs 8MoB5-4 — frequently asked
Is 55Cr3 stronger than 8MoB5-4?
Yes. 55Cr3 has a typical yield strength of 480 MPa (69.6 ksi) against 255 MPa (37 ksi) for 8MoB5-4 — about 88% more. Tensile strength is 800 MPa (116 ksi) vs 410 MPa (59.5 ksi).
Which is cheaper, 55Cr3 or 8MoB5-4?
8MoB5-4 is the lower-cost material: it sits in the budget tier ($) while 55Cr3 is standard ($$). 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, 55Cr3 or 8MoB5-4?
8MoB5-4. Its machinability rates good (55/100) against fair (50/100) for 55Cr3; for welding the order is 8MoB5-4 first (very good, 72/100) then 55Cr3 (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 55Cr3 and 8MoB5-4 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.