Steel 4150 vs 8640
Steel · grade comparison
Steel 4150 and 8640 are both steel grades, both high strength steel. 8640 is the stronger of the two: yield strength 570 MPa (82.7 ksi) against 520 MPa (75.4 ksi) for 4150, about 10% more. 8640 is the more ductile: elongation 19% versus 16% for 4150. On the shop floor, 8640 machines more easily (good vs fair), 8640 welds better (fair vs poor), and 8640 sits in a lower cost tier (standard, $$) than 4150 (premium, $$$).
8640Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
4150 vs 8640: 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)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Compressive Strength
Fracture Toughness (K_IC)
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) 860 MPa125 ksi
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
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Same in both: Max Service Temperature (continuous) 400°C752 °F · 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)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Same in both: Brazeability / Solderability 55 / 100 · Polishability 60 / 100
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.
Modulus of Resilience
Thermal Diffusivity
Same in both: Specific Strength (UTS / density) 110 kN·m/kg · Specific Stiffness (E / density) 26.1 MN·m/kg · Thermal Shock Resistance Index 15
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 | 4150 | 8640 |
|---|---|---|
| Default condition | HR | HR |
| Relative cost | $$$ Premium | $$ 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.
4150 vs 8640 — frequently asked
Is 8640 stronger than 4150?
Yes. 8640 has a typical yield strength of 570 MPa (82.7 ksi) against 520 MPa (75.4 ksi) for 4150 — about 10% more. Tensile strength is 860 MPa (125 ksi) vs 860 MPa (125 ksi).
Which is cheaper, 4150 or 8640?
8640 is the lower-cost material: it sits in the standard tier ($$) while 4150 is premium ($$$). 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, 4150 or 8640?
8640. Its machinability rates good (55/100) against fair (45/100) for 4150; for welding the order is 8640 first (fair, 40/100) then 4150 (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4150 and 8640 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.