Steel 18NCD6-HR vs 18NCD6 QT-30
Steel · 18NCD6 temper comparison
18NCD6-HR and 18NCD6 QT-30 are two conditions of the same steel grade, 18NCD6: HR (hot rolled) versus QT-30 (Q&T 28–34 HRC). The chemistry is identical, so every difference below comes from the condition. 18NCD6 QT-30 is the stronger of the two: yield strength 800 MPa (116 ksi) against 440 MPa (63.8 ksi) for 18NCD6-HR, about 82% more; tensile strength follows at 1,000 MPa (145 ksi) vs 700 MPa (102 ksi). In exchange, 18NCD6-HR is the more ductile: elongation 19% versus 15% for 18NCD6 QT-30, and 18NCD6 QT-30 is harder (300 HB vs 207 HB). On the shop floor, 18NCD6-HR machines more easily (53 vs 42 out of 100) and 18NCD6-HR welds better (fair vs poor).
18NCD6-HRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
18NCD6 QT-30Choose it when strength drives the design.
18NCD6-HR vs 18NCD6 QT-30: 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.
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 · Max Service Temperature (continuous) 200°C392 °F · 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)
Same in both: Brazeability / Solderability 60 / 100 · Polishability 65 / 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-HR vs 18NCD6 QT-30 — frequently asked
Is 18NCD6 QT-30 stronger than 18NCD6-HR?
Yes. 18NCD6 QT-30 has a typical yield strength of 800 MPa (116 ksi) against 440 MPa (63.8 ksi) for 18NCD6-HR — about 82% more. Tensile strength is 1,000 MPa (145 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, HR or QT-30?
A is the default 18NCD6 condition in the FabDigit quote flow (neither HR nor QT-30). 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-HR or 18NCD6 QT-30?
18NCD6-HR, by a small margin. Both rate fair for machinability — 53/100 against 42/100 for 18NCD6 QT-30; for welding the order is 18NCD6-HR first (fair, 45/100) then 18NCD6 QT-30 (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18NCD6-HR and 18NCD6 QT-30 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.