Steel P420QH-A vs P420QH QT-50-100
Steel · P420QH temper comparison
P420QH-A and P420QH QT-50-100 are two conditions of the same steel grade, P420QH: A (solution annealed) versus QT-50-100 (QT). The chemistry is identical, so every difference below comes from the condition. P420QH QT-50-100 is the stronger of the two: yield strength 445 MPa (64.5 ksi) against 330 MPa (47.9 ksi) for P420QH-A, about 35% more; tensile strength follows at 570 MPa (82.7 ksi) vs 500 MPa (72.5 ksi). In exchange, P420QH-A is the more ductile: elongation 26% versus 22% for P420QH QT-50-100, and P420QH QT-50-100 is harder (188 HB vs 155 HB). P420QH QT-50-100 runs hotter in service (400°C vs 350°C continuous).
P420QH-AChoose it when the part is bent, formed or impact-loaded.
P420QH QT-50-100Choose it when strength drives the design, or when the part sees heat.
P420QH-A vs P420QH QT-50-100: 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, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 81 GPa11.7 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.3
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.
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) 12 µm/m·K6.7 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.62 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
Formability (cold)
Same in both: Brazeability / Solderability 45 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 29 MJ/kg12,468 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 25%
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.
P420QH-A vs P420QH QT-50-100 — frequently asked
Is P420QH QT-50-100 stronger than P420QH-A?
Yes. P420QH QT-50-100 has a typical yield strength of 445 MPa (64.5 ksi) against 330 MPa (47.9 ksi) for P420QH-A — about 35% more. Tensile strength is 570 MPa (82.7 ksi) vs 500 MPa (72.5 ksi).
Which condition does FabDigit quote by default, A or QT-50-100?
QT is the default P420QH condition in the FabDigit quote flow (neither A nor QT-50-100). 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, P420QH-A or P420QH QT-50-100?
P420QH-A. Its machinability rates good (56/100) against fair (50/100) for P420QH QT-50-100; for welding the order is P420QH-A first (very good, 72/100) then P420QH QT-50-100 (good, 66/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in P420QH-A and P420QH QT-50-100 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.