Steel 4340 vs S960QL
Steel · grade comparison
Steel 4340 and S960QL are both steel grades, both high strength steel. S960QL is the stronger of the two: yield strength 1,010 MPa (146 ksi) against 620 MPa (89.9 ksi) for 4340, about 63% more; tensile strength follows at 1,050 MPa (152 ksi) vs 950 MPa (138 ksi). In exchange, 4340 is the more ductile: elongation 18% versus 12% for S960QL, and S960QL is harder (320 HB vs 285 HB). 4340 runs hotter in service (400°C vs 350°C continuous) and 4340 conducts heat better (44.5 W/m·K vs 34 W/m·K). On the shop floor, 4340 machines more easily (48 vs 35 out of 100), S960QL welds better (good vs poor), and S960QL sits in a lower cost tier (standard, $$) than 4340 (premium, $$$).
4340Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
S960QLChoose it when strength drives the design, or when it will be welded.
4340 vs S960QL: 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
Bulk Modulus
Poisson's Ratio
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
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
Max Service Temperature (continuous)
Same in both: Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Same in both: Electrical Conductivity 7 % IACS
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Same in both: Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb
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 | 4340 | S960QL |
|---|---|---|
| Default condition | HR | Q&T |
| 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.
4340 vs S960QL — frequently asked
Is S960QL stronger than 4340?
Yes. S960QL has a typical yield strength of 1,010 MPa (146 ksi) against 620 MPa (89.9 ksi) for 4340 — about 63% more. Tensile strength is 1,050 MPa (152 ksi) vs 950 MPa (138 ksi).
Which is cheaper, 4340 or S960QL?
S960QL is the lower-cost material: it sits in the standard tier ($$) while 4340 is premium ($$$). 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, 4340 or S960QL?
4340, by a small margin. Both rate fair for machinability — 48/100 against 35/100 for S960QL; for welding the order is S960QL first (good, 55/100) then 4340 (poor, 33/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4340 and S960QL 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.