Steel G18Mo5-QT vs G18Mo5-SR
Steel · G18Mo5 temper comparison
G18Mo5-QT and G18Mo5-SR are two conditions of the same steel grade, G18Mo5: QT (quenched and tempered) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. G18Mo5-QT is the stronger of the two: yield strength 360 MPa (52.2 ksi) against 275 MPa (39.9 ksi) for G18Mo5-SR, about 31% more; tensile strength follows at 560 MPa (81.2 ksi) vs 490 MPa (71.1 ksi). In exchange, G18Mo5-SR is the more ductile: elongation 26% versus 22% for G18Mo5-QT, and G18Mo5-QT is harder (170 HB vs 140 HB).
G18Mo5-QTChoose it when strength drives the design.
G18Mo5-SRChoose it when the part is bent, formed or impact-loaded.
G18Mo5-QT vs G18Mo5-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 81 GPa11.7 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) 1,425°C2,597 °F · Liquidus Temperature 1,505°C2,741 °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 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.2 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -10°C14 °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: Castability 70 / 100 · Brazeability / Solderability 45 / 100 · Polishability 45 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 28 MJ/kg12,038 BTU/lb · Embodied Carbon (primary production) 2.2 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 70%
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.
G18Mo5-QT vs G18Mo5-SR — frequently asked
Is G18Mo5-QT stronger than G18Mo5-SR?
Yes. G18Mo5-QT has a typical yield strength of 360 MPa (52.2 ksi) against 275 MPa (39.9 ksi) for G18Mo5-SR — about 31% more. Tensile strength is 560 MPa (81.2 ksi) vs 490 MPa (71.1 ksi).
Which condition does FabDigit quote by default, QT or SR?
N+T is the default G18Mo5 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, G18Mo5-QT or G18Mo5-SR?
G18Mo5-SR. Its machinability rates good (60/100) against fair (54/100) for G18Mo5-QT; for welding the order is G18Mo5-SR first (very good, 74/100) then G18Mo5-QT (good, 68/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in G18Mo5-QT and G18Mo5-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.