Steel NAK55 Nitrided vs NAK55 Prehard
Steel · NAK55 temper comparison
NAK55 Nitrided and NAK55 Prehard are two conditions of the same steel grade, NAK55: Nitrided versus Prehard (pre-hardened). The chemistry is identical, so every difference below comes from the condition. Both yield at about 1,100 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (Nitrided versus pre-hardened). NAK55 Prehard is the more ductile: elongation 10% versus 8% for NAK55 Nitrided, and NAK55 Nitrided is harder (680 HV vs 392 HV). On the shop floor, NAK55 Prehard machines more easily (good vs poor) and NAK55 Prehard welds better (fair vs not recommended).
NAK55 PrehardChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
NAK55 Nitrided vs NAK55 Prehard: 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.
Elongation at Break
Reduction in Area
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 206 GPa29.9 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.29 · Tensile Strength (Ultimate) 1,270 MPa184 ksi · Yield Strength (0.2% offset) 1,100 MPa160 ksi · Compressive Strength 1,150 MPa167 ksi · Shear Strength 760 MPa110 ksi · Hardness, Brinell 375 HB · Hardness, Rockwell C 40 HRC
Physical
Density and transition temperatures.
Same in both: Density 7.8 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) 12.4 µm/m·K6.9 µin/in·°F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 2.6×10⁻⁷ Ω·m10.2 µΩ·in
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)
Polishability
Same in both: Brazeability / Solderability 30 / 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 55 L/kg6.6 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.
NAK55 Nitrided vs NAK55 Prehard — frequently asked
What is the difference between NAK55 Nitrided and NAK55 Prehard?
NAK55 Nitrided and NAK55 Prehard are two conditions of the same steel grade, NAK55: Nitrided versus Prehard (pre-hardened). The chemistry is identical, so every difference below comes from the condition. Both yield at about 1,100 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (Nitrided versus pre-hardened).
Which condition does FabDigit quote by default, Nitrided or Prehard?
Annealed is the default NAK55 condition in the FabDigit quote flow (neither Nitrided nor Prehard). 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, NAK55 Nitrided or NAK55 Prehard?
NAK55 Prehard. Its machinability rates good (55/100) against poor (15/100) for NAK55 Nitrided; for welding the order is NAK55 Prehard first (fair, 40/100) then NAK55 Nitrided (not recommended, 8/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in NAK55 Nitrided and NAK55 Prehard 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.