Steel 27SiMn-CD vs 27SiMn-QT
Steel · 27SiMn temper comparison
27SiMn-CD and 27SiMn-QT are two conditions of the same steel grade, 27SiMn: CD (cold drawn) versus QT (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. 27SiMn-QT is the stronger of the two: yield strength 890 MPa (129 ksi) against 700 MPa (102 ksi) for 27SiMn-CD, about 27% more; tensile strength follows at 1,030 MPa (149 ksi) vs 900 MPa (131 ksi). 27SiMn-QT is the more ductile: elongation 15% versus 12% for 27SiMn-CD, and 27SiMn-QT is harder (310 HB vs 270 HB). 27SiMn-QT runs hotter in service (350°C vs 300°C continuous).
27SiMn-QTChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
27SiMn-CD vs 27SiMn-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
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
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) 1,420°C2,588 °F · Liquidus Temperature 1,490°C2,714 °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 470 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 -40°C-40 °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 11 / 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 45 / 100 · Polishability 65 / 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 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.
27SiMn-CD vs 27SiMn-QT — frequently asked
Is 27SiMn-QT stronger than 27SiMn-CD?
Yes. 27SiMn-QT has a typical yield strength of 890 MPa (129 ksi) against 700 MPa (102 ksi) for 27SiMn-CD — about 27% more. Tensile strength is 1,030 MPa (149 ksi) vs 900 MPa (131 ksi).
Which condition does FabDigit quote by default, CD or QT?
QT is the default 27SiMn 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, 27SiMn-CD or 27SiMn-QT?
27SiMn-CD, by a small margin. Both rate fair for machinability — 52/100 against 45/100 for 27SiMn-QT; for welding the order is 27SiMn-QT first (fair, 35/100) then 27SiMn-CD (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 27SiMn-CD and 27SiMn-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.