Steel 18NCD6-CD vs 18NCD6-CH
Steel · 18NCD6 temper comparison
18NCD6-CD and 18NCD6-CH are two conditions of the same steel grade, 18NCD6: CD (cold drawn) versus CH (carburized and hardened). The chemistry is identical, so every difference below comes from the condition. 18NCD6-CH is the stronger of the two: yield strength 900 MPa (131 ksi) against 580 MPa (84.1 ksi) for 18NCD6-CD, about 55% more; tensile strength follows at 1,150 MPa (167 ksi) vs 700 MPa (102 ksi). 18NCD6-CD is harder — 210 HB against 170 HB for 18NCD6-CH — which matters for wear surfaces and threads. 18NCD6-CD runs hotter in service (200°C vs 180°C continuous). On the shop floor, 18NCD6-CD machines more easily (good vs not recommended), 18NCD6-CD welds better (fair vs not recommended), and 18NCD6-CD forms better (fair vs not recommended).
18NCD6-CDChoose it when surface hardness matters, or when the part sees heat.
18NCD6-CHChoose it when strength drives the design.
18NCD6-CD vs 18NCD6-CH: 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
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
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
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,495°C2,723 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 43 W/m·K24.8 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.6 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 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)
Polishability
Same in both: Brazeability / Solderability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 29 MJ/kg12,468 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 25%
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.
18NCD6-CD vs 18NCD6-CH — frequently asked
Is 18NCD6-CH stronger than 18NCD6-CD?
Yes. 18NCD6-CH has a typical yield strength of 900 MPa (131 ksi) against 580 MPa (84.1 ksi) for 18NCD6-CD — about 55% more. Tensile strength is 1,150 MPa (167 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, CD or CH?
A is the default 18NCD6 condition in the FabDigit quote flow (neither CD nor CH). 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, 18NCD6-CD or 18NCD6-CH?
18NCD6-CD. Its machinability rates good (62/100) against not recommended (10/100) for 18NCD6-CH; for welding the order is 18NCD6-CD first (fair, 40/100) then 18NCD6-CH (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18NCD6-CD and 18NCD6-CH 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.