Steel NAK55 Annealed vs NAK55 Prehard
Steel · NAK55 temper comparison
NAK55 Annealed and NAK55 Prehard are two conditions of the same steel grade, NAK55: Annealed versus Prehard (pre-hardened). The chemistry is identical, so every difference below comes from the condition. NAK55 Prehard is the stronger of the two: yield strength 1,100 MPa (160 ksi) against 560 MPa (81.2 ksi) for NAK55 Annealed, about 96% more; tensile strength follows at 1,270 MPa (184 ksi) vs 800 MPa (116 ksi). In exchange, NAK55 Annealed is the more ductile: elongation 20% versus 10% for NAK55 Prehard, and NAK55 Prehard is harder (375 HB vs 245 HB). On the shop floor, NAK55 Annealed machines more easily (very good vs good).
NAK55 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
NAK55 PrehardChoose it when strength drives the design.
NAK55 Annealed 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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
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 · Reduction in Area 35% · Compressive Strength 1,150 MPa167 ksi · Shear Strength 760 MPa110 ksi · Fatigue Strength (Endurance Limit) 580 MPa84.1 ksi · Fracture Toughness (K_IC) 60 MPa·√m54.6 ksi·√in · Hardness, Vickers 392 HV
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.
Same in both: Thermal Conductivity 39 W/m·K22.5 BTU/hr·ft·°F · 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 · Max Service Temperature (continuous) 430°C806 °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).
Same in both: Corrosion Resistance 20 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Polishability
Same in both: Weldability 40 / 100 · Formability (cold) 30 / 100 · 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 Annealed vs NAK55 Prehard — frequently asked
Is NAK55 Prehard stronger than NAK55 Annealed?
Yes. NAK55 Prehard has a typical yield strength of 1,100 MPa (160 ksi) against 560 MPa (81.2 ksi) for NAK55 Annealed — about 96% more. Tensile strength is 1,270 MPa (184 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, Annealed or Prehard?
Annealed is the default NAK55 condition in the FabDigit quote flow. 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 Annealed or NAK55 Prehard?
NAK55 Annealed. Its machinability rates very good (70/100) against good (55/100) for NAK55 Prehard.
Ready to make it?
Upload a CAD file and FabDigit prices the part in NAK55 Annealed 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.