Steel ZG20CrMo-QT vs ZG20CrMo-SR
Steel · ZG20CrMo temper comparison
ZG20CrMo-QT and ZG20CrMo-SR are two conditions of the same steel grade, ZG20CrMo: QT (quenched and tempered) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. ZG20CrMo-QT is the stronger of the two: yield strength 470 MPa (68.2 ksi) against 280 MPa (40.6 ksi) for ZG20CrMo-SR, about 68% more; tensile strength follows at 660 MPa (95.7 ksi) vs 510 MPa (74 ksi). In exchange, ZG20CrMo-SR is the more ductile: elongation 22% versus 17% for ZG20CrMo-QT, and ZG20CrMo-QT is harder (205 HB vs 155 HB). On the shop floor, ZG20CrMo-SR machines more easily (good vs fair).
ZG20CrMo-QTChoose it when strength drives the design.
ZG20CrMo-SRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
ZG20CrMo-QT vs ZG20CrMo-SR: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
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
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,450°C2,642 °F · Liquidus Temperature 1,510°C2,750 °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 465 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 270 J/g116 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: 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) -0.62 V · Corrosion Resistance 13 / 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: Castability 65 / 100 · Brazeability / Solderability 55 / 100 · Polishability 60 / 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 75%
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.
ZG20CrMo-QT vs ZG20CrMo-SR — frequently asked
Is ZG20CrMo-QT stronger than ZG20CrMo-SR?
Yes. ZG20CrMo-QT has a typical yield strength of 470 MPa (68.2 ksi) against 280 MPa (40.6 ksi) for ZG20CrMo-SR — about 68% more. Tensile strength is 660 MPa (95.7 ksi) vs 510 MPa (74 ksi).
Which condition does FabDigit quote by default, QT or SR?
N+T is the default ZG20CrMo condition in the FabDigit quote flow (neither QT nor SR). 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, ZG20CrMo-QT or ZG20CrMo-SR?
ZG20CrMo-SR. Its machinability rates good (57/100) against fair (45/100) for ZG20CrMo-QT.
Ready to make it?
Upload a CAD file and FabDigit prices the part in ZG20CrMo-QT and ZG20CrMo-SR 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.