Steel SUM31-CD vs SUM31 CH-QT
Steel · SUM31 temper comparison
SUM31-CD and SUM31 CH-QT are two conditions of the same steel grade, SUM31: CD (cold drawn) versus CH-QT (carburized, quenched and low-temperature tempered). The chemistry is identical, so every difference below comes from the condition. SUM31 CH-QT is the stronger of the two: yield strength 480 MPa (69.6 ksi) against 400 MPa (58 ksi) for SUM31-CD, about 20% more; tensile strength follows at 700 MPa (102 ksi) vs 510 MPa (74 ksi). In exchange, SUM31-CD is the more ductile: elongation 15% versus 12% for SUM31 CH-QT, and SUM31 CH-QT is harder (700 HV vs 158 HV). SUM31-CD runs hotter in service (350°C vs 180°C continuous). On the shop floor, SUM31-CD machines more easily (very good vs poor) and SUM31-CD welds better (poor vs not recommended).
SUM31-CDChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
SUM31 CH-QTChoose it when strength drives the design.
SUM31-CD vs SUM31 CH-QT: 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)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Hardness, Brinell 150 HB · Hardness, Rockwell B 80 HRB
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 1,500°C2,732 °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 480 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.9 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 247 J/g106 BTU/lb · Min Service Temperature -20°C-4 °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) -0.61 V · Corrosion Resistance 10 / 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: Brazeability / Solderability 60 / 100 · Polishability 35 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Carbon (primary production) 2 kg CO₂/kg · Embodied Water 45 L/kg5.4 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.
SUM31-CD vs SUM31 CH-QT — frequently asked
Is SUM31 CH-QT stronger than SUM31-CD?
Yes. SUM31 CH-QT has a typical yield strength of 480 MPa (69.6 ksi) against 400 MPa (58 ksi) for SUM31-CD — about 20% more. Tensile strength is 700 MPa (102 ksi) vs 510 MPa (74 ksi).
Which condition does FabDigit quote by default, CD or CH-QT?
CD is the default SUM31 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, SUM31-CD or SUM31 CH-QT?
SUM31-CD. Its machinability rates very good (82/100) against poor (15/100) for SUM31 CH-QT; for welding the order is SUM31-CD first (poor, 30/100) then SUM31 CH-QT (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SUM31-CD and SUM31 CH-QT 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.