Steel En18-CD vs En18 QT34-38HRC
Steel · En18 temper comparison
En18-CD and En18 QT34-38HRC are two conditions of the same steel grade, En18: CD (cold drawn) versus QT34-38HRC (Q&T to 34–38 HRC). The chemistry is identical, so every difference below comes from the condition. En18 QT34-38HRC is the stronger of the two: yield strength 930 MPa (135 ksi) against 660 MPa (95.7 ksi) for En18-CD, about 41% more; tensile strength follows at 1,150 MPa (167 ksi) vs 800 MPa (116 ksi). En18 QT34-38HRC is harder — 340 HB against 240 HB for En18-CD — which matters for wear surfaces and threads. On the shop floor, En18-CD machines more easily (good vs fair), En18-CD welds better (fair vs poor), and En18-CD forms better (poor vs not recommended).
En18-CDChoose it when the part is machined in volume, or when it will be welded.
En18 QT34-38HRCChoose it when strength drives the design, or when surface hardness matters.
En18-CD vs En18 QT34-38HRC: 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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
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 · Charpy V-Notch Impact (RT) 25 J18.4 ft·lbf
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,495°C2,723 °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 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.62 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 55 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 33 MJ/kg14,187 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 35%
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.
En18-CD vs En18 QT34-38HRC — frequently asked
Is En18 QT34-38HRC stronger than En18-CD?
Yes. En18 QT34-38HRC has a typical yield strength of 930 MPa (135 ksi) against 660 MPa (95.7 ksi) for En18-CD — about 41% more. Tensile strength is 1,150 MPa (167 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, CD or QT34-38HRC?
T is the default En18 condition in the FabDigit quote flow (neither CD nor QT34-38HRC). 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, En18-CD or En18 QT34-38HRC?
En18-CD. Its machinability rates good (58/100) against fair (35/100) for En18 QT34-38HRC; for welding the order is En18-CD first (fair, 35/100) then En18 QT34-38HRC (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in En18-CD and En18 QT34-38HRC 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.