Steel 40CrNi-QT vs 40CrNi QT-38-42HRC
Steel · 40CrNi temper comparison
40CrNi-QT and 40CrNi QT-38-42HRC are two conditions of the same steel grade, 40CrNi: QT (quenched and tempered) versus QT-38-42HRC. The chemistry is identical, so every difference below comes from the condition. 40CrNi QT-38-42HRC is the stronger of the two: yield strength 1,180 MPa (171 ksi) against 840 MPa (122 ksi) for 40CrNi-QT, about 40% more; tensile strength follows at 1,330 MPa (193 ksi) vs 1,020 MPa (148 ksi). In exchange, 40CrNi-QT is the more ductile: elongation 12% versus 10% for 40CrNi QT-38-42HRC, and 40CrNi QT-38-42HRC is harder (375 HB vs 300 HB). 40CrNi-QT runs hotter in service (400°C vs 300°C continuous). On the shop floor, 40CrNi-QT machines more easily (fair vs poor).
40CrNi-QTChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
40CrNi QT-38-42HRCChoose it when strength drives the design.
40CrNi-QT vs 40CrNi QT-38-42HRC: 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
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 860 MPa125 ksi · Shear Strength 620 MPa89.9 ksi · Fracture Toughness (K_IC) 85 MPa·√m77.4 ksi·√in
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 42 W/m·K24.3 BTU/hr·ft·°F · Specific Heat Capacity 470 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 -60°C-76 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.5 % IACS · Electrical Resistivity 2.3×10⁻⁷ Ω·m9.06 µΩ·in
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 %)
Same in both: Weldability 30 / 100 · Formability (cold) 25 / 100 · Brazeability / Solderability 45 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 26 MJ/kg11,178 BTU/lb · Embodied Carbon (primary production) 2 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 30%
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.
40CrNi-QT vs 40CrNi QT-38-42HRC — frequently asked
Is 40CrNi QT-38-42HRC stronger than 40CrNi-QT?
Yes. 40CrNi QT-38-42HRC has a typical yield strength of 1,180 MPa (171 ksi) against 840 MPa (122 ksi) for 40CrNi-QT — about 40% more. Tensile strength is 1,330 MPa (193 ksi) vs 1,020 MPa (148 ksi).
Which condition does FabDigit quote by default, QT or QT-38-42HRC?
QT is the default 40CrNi condition in the FabDigit quote flow. 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, 40CrNi-QT or 40CrNi QT-38-42HRC?
40CrNi-QT. Its machinability rates fair (50/100) against poor (32/100) for 40CrNi QT-38-42HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 40CrNi-QT and 40CrNi QT-38-42HRC 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.