Steel S45C-A vs S45C-QT
Steel · S45C temper comparison
S45C-A and S45C-QT are two conditions of the same steel grade, S45C: A (solution annealed) versus QT (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. S45C-QT is the stronger of the two: yield strength 550 MPa (79.8 ksi) against 310 MPa (45 ksi) for S45C-A, about 77% more; tensile strength follows at 750 MPa (109 ksi) vs 570 MPa (82.7 ksi). In exchange, S45C-A is the more ductile: elongation 24% versus 18% for S45C-QT, and S45C-QT is harder (235 HB vs 163 HB). On the shop floor, S45C-A welds better (50 vs 35 out of 100).
S45C-AChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
S45C-QTChoose it when strength drives the design.
S45C-A vs S45C-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 B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 380 MPa55.1 ksi
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 1,495°C2,723 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 49 W/m·K28.3 BTU/hr·ft·°F · Specific Heat Capacity 486 J/kg·K0.12 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.7 µm/m·K6.5 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10.7 % IACS · Electrical Resistivity 1.62×10⁻⁷ Ω·m6.38 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
Weldability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 55% · Castability 45 / 100 · Brazeability / Solderability 65 / 100 · Polishability 60 / 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 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.
S45C-A vs S45C-QT — frequently asked
Is S45C-QT stronger than S45C-A?
Yes. S45C-QT has a typical yield strength of 550 MPa (79.8 ksi) against 310 MPa (45 ksi) for S45C-A — about 77% more. Tensile strength is 750 MPa (109 ksi) vs 570 MPa (82.7 ksi).
Which condition does FabDigit quote by default, A or QT?
Normalized is the default S45C condition in the FabDigit quote flow (neither A nor QT). 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 welds better, S45C-A or S45C-QT?
S45C-A. Its weldability rates fair (50/100) against fair (35/100) for S45C-QT.
Ready to make it?
Upload a CAD file and FabDigit prices the part in S45C-A and S45C-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.