Steel 31CrMoV9 +A vs 31CrMoV9 Q&T 40-100
Steel · 31CrMoV9 temper comparison
31CrMoV9 +A and 31CrMoV9 Q&T 40-100 are two conditions of the same steel grade, 31CrMoV9: +A (annealed) versus Q&T 40-100 (+QT). The chemistry is identical, so every difference below comes from the condition. 31CrMoV9 Q&T 40-100 is the stronger of the two: yield strength 780 MPa (113 ksi) against 550 MPa (79.8 ksi) for 31CrMoV9 +A, about 42% more; tensile strength follows at 1,000 MPa (145 ksi) vs 800 MPa (116 ksi). In exchange, 31CrMoV9 +A is the more ductile: elongation 16% versus 13% for 31CrMoV9 Q&T 40-100, and 31CrMoV9 Q&T 40-100 is harder (300 HB vs 230 HB).
31CrMoV9 +AChoose it when the part is bent, formed or impact-loaded.
31CrMoV9 Q&T 40-100Choose it when strength drives the design.
31CrMoV9 +A vs 31CrMoV9 Q&T 40-100: 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.
31CrMoV9 +A31CrMoV9 Q&T 40-100
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)
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 · Charpy V-Notch Impact (RT) 45 J33.2 ft·lbf
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 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 36 W/m·K20.8 BTU/hr·ft·°F · Specific Heat Capacity 465 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 · Max Service Temperature (continuous) 450°C842 °F · Min Service Temperature -40°C-40 °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: Corrosion Resistance 16 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 20 / 100 · Castability 25 / 100 · Brazeability / Solderability 45 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 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.
31CrMoV9 +A vs 31CrMoV9 Q&T 40-100 — frequently asked
Is 31CrMoV9 Q&T 40-100 stronger than 31CrMoV9 +A?
Yes. 31CrMoV9 Q&T 40-100 has a typical yield strength of 780 MPa (113 ksi) against 550 MPa (79.8 ksi) for 31CrMoV9 +A — about 42% more. Tensile strength is 1,000 MPa (145 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, +A or Q&T 40-100?
Q&T is the default 31CrMoV9 condition in the FabDigit quote flow (neither +A nor Q&T 40-100). 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, 31CrMoV9 +A or 31CrMoV9 Q&T 40-100?
31CrMoV9 +A, by a small margin. Both rate fair for machinability — 50/100 against 44/100 for 31CrMoV9 Q&T 40-100.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 31CrMoV9 +A and 31CrMoV9 Q&T 40-100 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.