Steel 4140 vs 8630
Steel · grade comparison
Steel 4140 and 8630 are both steel grades. 4140 is the stronger of the two: yield strength 480 MPa (69.6 ksi) against 415 MPa (60.2 ksi) for 8630, about 16% more. 4140 is harder — 210 HB against 197 HB for 8630 — which matters for wear surfaces and threads.
4140Choose it when strength drives the design, or when surface hardness matters.
4140 vs 8630: 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.
Yield Strength (0.2% offset)
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Tensile Strength (Ultimate) 690 MPa100 ksi · Elongation at Break 22% · Reduction in Area 50%
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 Conductivity
Specific Heat Capacity
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb
Electrical
Conductivity and insulation.
Electrical Conductivity
Same in both: Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability Rating (AISI 1212 = 100 %)
Polishability
Castability
Same in both: Machinability 60 / 100 · Weldability 40 / 100 · Formability (cold) 40 / 100 · Brazeability / Solderability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 2.2 kg CO₂/kg
Common Calculations
Ratios derived from the values above.
Modulus of Resilience
Same in both: Specific Strength (UTS / density) 88 kN·m/kg · Specific Stiffness (E / density) 26.1 MN·m/kg · Thermal Diffusivity 11.5 mm²/s · Thermal Shock Resistance Index 12
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 | 4140 | 8630 |
|---|---|---|
| Casting & forging | Yes | — |
| Default condition | HR | 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.
4140 vs 8630 — frequently asked
Is 4140 stronger than 8630?
Yes. 4140 has a typical yield strength of 480 MPa (69.6 ksi) against 415 MPa (60.2 ksi) for 8630 — about 16% more. Tensile strength is 690 MPa (100 ksi) vs 690 MPa (100 ksi).
Which is cheaper, 4140 or 8630?
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.
When should I choose 4140 over 8630?
Pick 4140 when strength drives the design, or when surface hardness matters.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4140 and 8630 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.