Steel 718H vs NAK55
Steel · grade comparison
Steel 718H and NAK55 are both steel grades, both mold steel. 718H is the stronger of the two: yield strength 900 MPa (131 ksi) against 560 MPa (81.2 ksi) for NAK55, about 61% more; tensile strength follows at 1,080 MPa (157 ksi) vs 800 MPa (116 ksi). In exchange, NAK55 is the more ductile: elongation 20% versus 13% for 718H, and 718H is harder (300 HB vs 245 HB). NAK55 conducts heat better (39 W/m·K vs 33 W/m·K). On the shop floor, NAK55 machines more easily (very good vs fair).
718HChoose it when strength drives the design.
NAK55Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
718H vs NAK55: 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
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Compressive Strength
Same in both: Shear Modulus 80 GPa11.6 Msi · Poisson's Ratio 0.29
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
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
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 %)
Formability (cold)
Brazeability / Solderability
Polishability
Same in both: Weldability 40 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/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 | 718H | NAK55 |
|---|---|---|
| Default condition | Prehard | Annealed |
| Relative cost | $$ Standard | $$ 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. 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.
718H vs NAK55 — frequently asked
Is 718H stronger than NAK55?
Yes. 718H has a typical yield strength of 900 MPa (131 ksi) against 560 MPa (81.2 ksi) for NAK55 — about 61% more. Tensile strength is 1,080 MPa (157 ksi) vs 800 MPa (116 ksi).
Which is cheaper, 718H or NAK55?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, 718H or NAK55?
NAK55. Its machinability rates very good (70/100) against fair (48/100) for 718H.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 718H and NAK55 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.