Steel SCM421-CD vs SCM421 QT-285HB
Steel · SCM421 temper comparison
SCM421-CD and SCM421 QT-285HB are two conditions of the same steel grade, SCM421: CD (cold drawn) versus QT-285HB (Q&T core condition). The chemistry is identical, so every difference below comes from the condition. SCM421 QT-285HB is the stronger of the two: yield strength 780 MPa (113 ksi) against 590 MPa (85.6 ksi) for SCM421-CD, about 32% more; tensile strength follows at 950 MPa (138 ksi) vs 700 MPa (102 ksi). SCM421 QT-285HB is the more ductile: elongation 15% versus 12% for SCM421-CD, and SCM421 QT-285HB is harder (285 HB vs 210 HB). SCM421 QT-285HB runs hotter in service (400°C vs 200°C continuous).
SCM421 QT-285HBChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
SCM421-CD vs SCM421 QT-285HB: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Same in both: Elastic (Young's) Modulus 206 GPa29.9 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) 1,425°C2,597 °F · Liquidus Temperature 1,500°C2,732 °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 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 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · 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) -0.61 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: Brazeability / Solderability 60 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 30%
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.
SCM421-CD vs SCM421 QT-285HB — frequently asked
Is SCM421 QT-285HB stronger than SCM421-CD?
Yes. SCM421 QT-285HB has a typical yield strength of 780 MPa (113 ksi) against 590 MPa (85.6 ksi) for SCM421-CD — about 32% more. Tensile strength is 950 MPa (138 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, CD or QT-285HB?
A is the default SCM421 condition in the FabDigit quote flow (neither CD nor QT-285HB). 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, SCM421-CD or SCM421 QT-285HB?
SCM421-CD, by a small margin. Both rate good for machinability — 67/100 against 62/100 for SCM421 QT-285HB.
Ready to make it?
Upload a CAD file and FabDigit prices the part in SCM421-CD and SCM421 QT-285HB 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.