Steel En39-HR vs En39-QT
Steel · En39 temper comparison
En39-HR and En39-QT are two conditions of the same steel grade, En39: HR (hot rolled) versus QT (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. En39-QT is the stronger of the two: yield strength 1,000 MPa (145 ksi) against 800 MPa (116 ksi) for En39-HR, about 25% more; tensile strength follows at 1,250 MPa (181 ksi) vs 1,100 MPa (160 ksi). En39-QT is harder — 375 HB against 340 HB for En39-HR — which matters for wear surfaces and threads. En39-QT runs hotter in service (300°C vs 180°C continuous). On the shop floor, En39-QT welds better (poor vs not recommended) and En39-QT forms better (fair vs poor).
En39-QTChoose it when strength drives the design, or when surface hardness matters.
En39-HR vs En39-QT: 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)
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
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 · Elongation at Break 12%
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 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 34 W/m·K19.6 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.8 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -70°C-94 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 5.8 % IACS · Electrical Resistivity 3×10⁻⁷ Ω·m11.8 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 14 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Weldability
Formability (cold)
Same in both: Machinability 22 / 100 · Machinability Rating (AISI 1212 = 100 %) 22% · Brazeability / Solderability 45 / 100 · Polishability 70 / 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 75 L/kg9 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.
En39-HR vs En39-QT — frequently asked
Is En39-QT stronger than En39-HR?
Yes. En39-QT has a typical yield strength of 1,000 MPa (145 ksi) against 800 MPa (116 ksi) for En39-HR — about 25% more. Tensile strength is 1,250 MPa (181 ksi) vs 1,100 MPa (160 ksi).
Which condition does FabDigit quote by default, HR or QT?
A is the default En39 condition in the FabDigit quote flow (neither HR nor QT). 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 welds better, En39-HR or En39-QT?
En39-QT. Its weldability rates poor (20/100) against not recommended (10/100) for En39-HR.
Ready to make it?
Upload a CAD file and FabDigit prices the part in En39-HR and En39-QT 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.