Steel S7 Hardened & Tempered vs S7 Nitrided
Steel · S7 temper comparison
S7 Hardened & Tempered and S7 Nitrided are two conditions of the same steel grade, S7: Hardened & Tempered (quenched and tempered) versus Nitrided. The chemistry is identical, so every difference below comes from the condition. Both yield at about 1,600 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (quenched and tempered versus Nitrided). S7 Nitrided is harder — 1,000 HV against 620 HV for S7 Hardened & Tempered — which matters for wear surfaces and threads. S7 Nitrided runs hotter in service (480°C vs 400°C continuous). On the shop floor, S7 Hardened & Tempered welds better (poor vs not recommended) and S7 Hardened & Tempered forms better (fair vs not recommended).
S7 Hardened & TemperedChoose it when it will be welded.
S7 NitridedChoose it when surface hardness matters, or when the part sees heat.
S7 Hardened & Tempered vs S7 Nitrided: 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.
S7 Hardened & TemperedS7 Nitrided
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 207 GPa30 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 1,600 MPa232 ksi · Elongation at Break 6% · Fracture Toughness (K_IC) 50 MPa·√m45.5 ksi·√in · Hardness, Brinell 200 HB · Hardness, Rockwell B 94 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 1,480°C2,696 °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) 12.6 µm/m·K7 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
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)
Same in both: Brazeability / Solderability 40 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 36 MJ/kg15,477 BTU/lb · Embodied Carbon (primary production) 2.7 kg CO₂/kg · Embodied Water 65 L/kg7.8 gal/lb · Typical Recycled Content 40%
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.
S7 Hardened & Tempered vs S7 Nitrided — frequently asked
What is the difference between S7 Hardened & Tempered and S7 Nitrided?
S7 Hardened & Tempered and S7 Nitrided are two conditions of the same steel grade, S7: Hardened & Tempered (quenched and tempered) versus Nitrided. The chemistry is identical, so every difference below comes from the condition. Both yield at about 1,600 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (quenched and tempered versus Nitrided).
Which condition does FabDigit quote by default, Hardened & Tempered or Nitrided?
Annealed is the default S7 condition in the FabDigit quote flow (neither Hardened & Tempered nor Nitrided). 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, S7 Hardened & Tempered or S7 Nitrided?
S7 Hardened & Tempered, by a small margin. Both rate not recommended for machinability — 12/100 against 5/100 for S7 Nitrided; for welding the order is S7 Hardened & Tempered first (poor, 30/100) then S7 Nitrided (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in S7 Hardened & Tempered and S7 Nitrided 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.