Steel 34MnB5 vs 8MoB5-4
Steel · grade comparison
Steel 34MnB5 and 8MoB5-4 are both steel grades. 34MnB5 is the stronger of the two: yield strength 420 MPa (60.9 ksi) against 255 MPa (37 ksi) for 8MoB5-4, about 65% more; tensile strength follows at 620 MPa (89.9 ksi) vs 410 MPa (59.5 ksi). In exchange, 8MoB5-4 is the more ductile: elongation 30% versus 14% for 34MnB5, and 34MnB5 is harder (185 HB vs 135 HB). On the shop floor, 8MoB5-4 welds better (very good vs good) and 8MoB5-4 sits in a lower cost tier (budget, $) than 34MnB5 (standard, $$).
34MnB5Choose it when strength drives the design.
8MoB5-4Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
34MnB5 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.
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
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · 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.
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Same in both: Thermal Conductivity 44 W/m·K25.4 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°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
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.
Weldability
Formability (cold)
Brazeability / Solderability
Same in both: Machinability 55 / 100 · Machinability Rating (AISI 1212 = 100 %) 60% · Polishability 55 / 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)
Modulus of Resilience
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 26.8 MN·m/kg · Thermal Diffusivity 11.9 mm²/s
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 | 34MnB5 | 8MoB5-4 |
|---|---|---|
| Sheet metal | Yes | — |
| Default condition | CR | — |
| Relative cost | $$ Standard | $ Budget |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Black Oxide | Yes | — |
| Cerakote | Yes | — |
| Chrome Plating | Yes | — |
| E-Coating | Yes | — |
| Hot-Dip Galvanizing | Yes | — |
| Nickel Plating | Yes | — |
| PTFE Coating | Yes | — |
| Painting | Yes | — |
| Powder Coating | Yes | — |
| Tin Plating | Yes | — |
| Zinc Plating | Yes | — |
| Zinc-Flake (Dip-Spin) Coating | Yes | — |
| Zinc-Nickel Plating | 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.
34MnB5 vs 8MoB5-4 — frequently asked
Is 34MnB5 stronger than 8MoB5-4?
Yes. 34MnB5 has a typical yield strength of 420 MPa (60.9 ksi) against 255 MPa (37 ksi) for 8MoB5-4 — about 65% more. Tensile strength is 620 MPa (89.9 ksi) vs 410 MPa (59.5 ksi).
Which is cheaper, 34MnB5 or 8MoB5-4?
8MoB5-4 is the lower-cost material: it sits in the budget tier ($) while 34MnB5 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 welds better, 34MnB5 or 8MoB5-4?
8MoB5-4. Its weldability rates very good (72/100) against good (55/100) for 34MnB5.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 34MnB5 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.