Steel SNCM420-A vs SNCM420-QT
Steel · SNCM420 temper comparison
SNCM420-A and SNCM420-QT are two conditions of the same steel grade, SNCM420: A (solution annealed) versus QT (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. SNCM420-QT is the stronger of the two: yield strength 900 MPa (131 ksi) against 455 MPa (66 ksi) for SNCM420-A, about 98% more; tensile strength follows at 1,080 MPa (157 ksi) vs 700 MPa (102 ksi). In exchange, SNCM420-A is the more ductile: elongation 22% versus 17% for SNCM420-QT, and SNCM420-QT is harder (320 HB vs 197 HB). SNCM420-QT runs hotter in service (300°C vs 250°C continuous). On the shop floor, SNCM420-A machines more easily (good vs fair) and SNCM420-A welds better (fair vs poor).
SNCM420-AChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
SNCM420-QTChoose it when strength drives the design, or when the part sees heat.
SNCM420-A vs SNCM420-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)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
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 · Hardness, Rockwell B 92 HRB
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 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 38 W/m·K22 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 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 · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.5 % IACS · Electrical Resistivity 2.3×10⁻⁷ Ω·m9.06 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.65 V · Corrosion Resistance 13 / 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) 50 / 100 · Brazeability / Solderability 55 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 32 MJ/kg13,758 BTU/lb · Embodied Carbon (primary production) 2.3 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.
SNCM420-A vs SNCM420-QT — frequently asked
Is SNCM420-QT stronger than SNCM420-A?
Yes. SNCM420-QT has a typical yield strength of 900 MPa (131 ksi) against 455 MPa (66 ksi) for SNCM420-A — about 98% more. Tensile strength is 1,080 MPa (157 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, A or QT?
A is the default SNCM420 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, SNCM420-A or SNCM420-QT?
SNCM420-A. Its machinability rates good (60/100) against fair (38/100) for SNCM420-QT; for welding the order is SNCM420-A first (fair, 40/100) then SNCM420-QT (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SNCM420-A and SNCM420-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.