Steel 4150 vs 8660
Steel · grade comparison
Steel 4150 and 8660 are both steel grades, both high strength steel. 8660 is the stronger of the two: yield strength 585 MPa (84.8 ksi) against 520 MPa (75.4 ksi) for 4150, about 13% more; tensile strength follows at 965 MPa (140 ksi) vs 860 MPa (125 ksi). In exchange, 4150 is the more ductile: elongation 16% versus 13% for 8660, and 8660 is harder (285 HB vs 235 HB). On the shop floor, 8660 sits in a lower cost tier (standard, $$) than 4150 (premium, $$$).
4150Choose it when the part is bent, formed or impact-loaded.
8660Choose it when strength drives the design, or when cost is the deciding factor.
4150 vs 8660: 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)
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
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
Min Service Temperature
Same in both: Max Service Temperature (continuous) 400°C752 °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.
Machinability
Weldability
Castability
Brazeability / Solderability
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 50% · Formability (cold) 25 / 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.
Specific Strength (UTS / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 26.1 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 | 4150 | 8660 |
|---|---|---|
| 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 8660 — frequently asked
Is 8660 stronger than 4150?
Yes. 8660 has a typical yield strength of 585 MPa (84.8 ksi) against 520 MPa (75.4 ksi) for 4150 — about 13% more. Tensile strength is 965 MPa (140 ksi) vs 860 MPa (125 ksi).
Which is cheaper, 4150 or 8660?
8660 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 8660?
4150, by a small margin. Both rate fair for machinability — 45/100 against 40/100 for 8660; for welding the order is 4150 first (poor, 25/100) then 8660 (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4150 and 8660 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.