Steel 100CrMnMoSi8-4-6-S2 vs 100CrMnMoSi8-4-6 +U
Steel · 100CrMnMoSi8-4-6 temper comparison
100CrMnMoSi8-4-6-S2 and 100CrMnMoSi8-4-6 +U are two conditions of the same steel grade, 100CrMnMoSi8-4-6: S2 (hardened + stabilized ~250 °C, 56–59 HRC) versus +U (hot rolled). The chemistry is identical, so every difference below comes from the condition. 100CrMnMoSi8-4-6-S2 is the stronger of the two: yield strength 1,750 MPa (254 ksi) against 950 MPa (138 ksi) for 100CrMnMoSi8-4-6 +U, about 84% more; tensile strength follows at 2,000 MPa (290 ksi) vs 1,250 MPa (181 ksi). In exchange, 100CrMnMoSi8-4-6 +U is the more ductile: elongation 6% versus 1.5% for 100CrMnMoSi8-4-6-S2, and 100CrMnMoSi8-4-6-S2 is harder (590 HB vs 380 HB). 100CrMnMoSi8-4-6-S2 runs hotter in service (250°C vs 200°C continuous).
100CrMnMoSi8-4-6-S2Choose it when strength drives the design, or when the part sees heat.
100CrMnMoSi8-4-6 +UChoose it when the part is bent, formed or impact-loaded.
100CrMnMoSi8-4-6-S2 vs 100CrMnMoSi8-4-6 +U: 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.
100CrMnMoSi8-4-6-S2100CrMnMoSi8-4-6 +U
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3 · Hardness, Rockwell B 97 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.83 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,460°C2,660 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12 µm/m·K6.7 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · 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)
Same in both: Castability 30 / 100 · Brazeability / Solderability 30 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/lb · Embodied Carbon (primary production) 2.5 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 30%
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.
100CrMnMoSi8-4-6-S2 vs 100CrMnMoSi8-4-6 +U — frequently asked
Is 100CrMnMoSi8-4-6-S2 stronger than 100CrMnMoSi8-4-6 +U?
Yes. 100CrMnMoSi8-4-6-S2 has a typical yield strength of 1,750 MPa (254 ksi) against 950 MPa (138 ksi) for 100CrMnMoSi8-4-6 +U — about 84% more. Tensile strength is 2,000 MPa (290 ksi) vs 1,250 MPa (181 ksi).
Which condition does FabDigit quote by default, S2 or +U?
+A is the default 100CrMnMoSi8-4-6 condition in the FabDigit quote flow (neither S2 nor +U). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, 100CrMnMoSi8-4-6-S2 or 100CrMnMoSi8-4-6 +U?
100CrMnMoSi8-4-6 +U, by a small margin. Both rate not recommended for machinability — 12/100 against 6/100 for 100CrMnMoSi8-4-6-S2.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 100CrMnMoSi8-4-6-S2 and 100CrMnMoSi8-4-6 +U 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.