Steel SC450-QT vs SC450-SR
Steel · SC450 temper comparison
SC450-QT and SC450-SR are two conditions of the same steel grade, SC450: QT (quenched and tempered) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. SC450-QT is the stronger of the two: yield strength 410 MPa (59.5 ksi) against 270 MPa (39.2 ksi) for SC450-SR, about 52% more; tensile strength follows at 590 MPa (85.6 ksi) vs 485 MPa (70.3 ksi). In exchange, SC450-SR is the more ductile: elongation 25% versus 21% for SC450-QT, and SC450-QT is harder (185 HB vs 140 HB). On the shop floor, SC450-SR machines more easily (good vs fair).
SC450-QTChoose it when strength drives the design.
SC450-SRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
SC450-QT vs SC450-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 205 GPa29.7 Msi · Shear Modulus 79 GPa11.5 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.
Min Service Temperature
Same in both: Thermal Conductivity 50 W/m·K28.9 BTU/hr·ft·°F · Specific Heat Capacity 470 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 250 J/g107 BTU/lb · Max Service Temperature (continuous) 425°C797 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10 % IACS · Electrical Resistivity 1.7×10⁻⁷ Ω·m6.69 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.65 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
Same in both: Formability (cold) 20 / 100 · Castability 70 / 100 · Brazeability / Solderability 65 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 26 MJ/kg11,178 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 50 L/kg6 gal/lb · Typical Recycled Content 80%
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.
SC450-QT vs SC450-SR — frequently asked
Is SC450-QT stronger than SC450-SR?
Yes. SC450-QT has a typical yield strength of 410 MPa (59.5 ksi) against 270 MPa (39.2 ksi) for SC450-SR — about 52% more. Tensile strength is 590 MPa (85.6 ksi) vs 485 MPa (70.3 ksi).
Which condition does FabDigit quote by default, QT or SR?
N is the default SC450 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, SC450-QT or SC450-SR?
SC450-SR. Its machinability rates good (64/100) against fair (53/100) for SC450-QT; for welding the order is SC450-SR first (very good, 80/100) then SC450-QT (very good, 72/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SC450-QT and SC450-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.