Stainless Steel 420HC-QT45 vs 420HC-SR
Stainless Steel · 420HC temper comparison
420HC-QT45 and 420HC-SR are two conditions of the same stainless steel grade, 420HC: QT45 (hardened and tempered to 42–46 HRC) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. 420HC-SR is the stronger of the two: yield strength 1,650 MPa (239 ksi) against 1,200 MPa (174 ksi) for 420HC-QT45, about 38% more; tensile strength follows at 2,020 MPa (293 ksi) vs 1,450 MPa (210 ksi). In exchange, 420HC-QT45 is the more ductile: elongation 8% versus 2% for 420HC-SR, and 420HC-SR is harder (615 HB vs 195 HB). 420HC-QT45 runs hotter in service (350°C vs 150°C continuous). On the shop floor, 420HC-QT45 machines more easily (poor vs not recommended) and 420HC-QT45 welds better (poor vs not recommended).
420HC-QT45Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
420HC-SRChoose it when strength drives the design.
420HC-QT45 vs 420HC-SR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless 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 stainless 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, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.28 · Hardness, Rockwell B 92 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,450°C2,642 °F · Liquidus Temperature 1,510°C2,750 °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 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.3 µm/m·K5.7 µin/in·°F · Latent Heat of Fusion 265 J/g114 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.3 V
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 35 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 46 MJ/kg19,776 BTU/lb · Embodied Carbon (primary production) 3 kg CO₂/kg · Embodied Water 250 L/kg30 gal/lb · Typical Recycled Content 45%
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
420HC-QT45 vs 420HC-SR — frequently asked
Is 420HC-SR stronger than 420HC-QT45?
Yes. 420HC-SR has a typical yield strength of 1,650 MPa (239 ksi) against 1,200 MPa (174 ksi) for 420HC-QT45 — about 38% more. Tensile strength is 2,020 MPa (293 ksi) vs 1,450 MPa (210 ksi).
Which condition does FabDigit quote by default, QT45 or SR?
A is the default 420HC condition in the FabDigit quote flow (neither QT45 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, 420HC-QT45 or 420HC-SR?
420HC-QT45. Its machinability rates poor (25/100) against not recommended (6/100) for 420HC-SR; for welding the order is 420HC-QT45 first (poor, 30/100) then 420HC-SR (not recommended, 8/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 420HC-QT45 and 420HC-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.