Steel 5CrNiMo QT30-34 vs 5CrNiMo QT38-42
Steel · 5CrNiMo temper comparison
5CrNiMo QT30-34 and 5CrNiMo QT38-42 are two conditions of the same steel grade, 5CrNiMo: QT30-34 (Q&T 30–34 HRC) versus QT38-42 (Q&T 38–42 HRC). The chemistry is identical, so every difference below comes from the condition. 5CrNiMo QT38-42 is the stronger of the two: yield strength 1,120 MPa (162 ksi) against 880 MPa (128 ksi) for 5CrNiMo QT30-34, about 27% more; tensile strength follows at 1,300 MPa (189 ksi) vs 1,050 MPa (152 ksi). In exchange, 5CrNiMo QT30-34 is the more ductile: elongation 15% versus 11% for 5CrNiMo QT38-42, and 5CrNiMo QT30-34 is harder (302 HB vs 220 HB). 5CrNiMo QT30-34 runs hotter in service (500°C vs 450°C continuous). On the shop floor, 5CrNiMo QT30-34 machines more easily (34 vs 22 out of 100).
5CrNiMo QT30-34Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
5CrNiMo QT38-42Choose it when strength drives the design.
5CrNiMo QT30-34 vs 5CrNiMo QT38-42: 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.
5CrNiMo QT30-345CrNiMo QT38-42
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 81 GPa11.7 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Same in both: Density 7.83 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 33 W/m·K19.1 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.5 µm/m·K6.9 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 2.6×10⁻⁷ Ω·m10.2 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: 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 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 32 MJ/kg13,758 BTU/lb · Embodied Carbon (primary production) 2.4 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.
5CrNiMo QT30-34 vs 5CrNiMo QT38-42 — frequently asked
Is 5CrNiMo QT38-42 stronger than 5CrNiMo QT30-34?
Yes. 5CrNiMo QT38-42 has a typical yield strength of 1,120 MPa (162 ksi) against 880 MPa (128 ksi) for 5CrNiMo QT30-34 — about 27% more. Tensile strength is 1,300 MPa (189 ksi) vs 1,050 MPa (152 ksi).
Which condition does FabDigit quote by default, QT30-34 or QT38-42?
Annealed is the default 5CrNiMo condition in the FabDigit quote flow (neither QT30-34 nor QT38-42). 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, 5CrNiMo QT30-34 or 5CrNiMo QT38-42?
5CrNiMo QT30-34, by a small margin. Both rate poor for machinability — 34/100 against 22/100 for 5CrNiMo QT38-42.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 5CrNiMo QT30-34 and 5CrNiMo QT38-42 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.