Steel 50B50-HR vs 50B50-QT540
Steel · 50B50 temper comparison
50B50-HR and 50B50-QT540 are two conditions of the same steel grade, 50B50: HR (hot rolled) versus QT540. The chemistry is identical, so every difference below comes from the condition. 50B50-QT540 is the stronger of the two: yield strength 1,060 MPa (154 ksi) against 460 MPa (66.7 ksi) for 50B50-HR, about 130% more; tensile strength follows at 1,150 MPa (167 ksi) vs 800 MPa (116 ksi). 50B50-QT540 is harder — 340 HB against 235 HB for 50B50-HR — which matters for wear surfaces and threads. 50B50-QT540 runs hotter in service (480°C vs 400°C continuous). On the shop floor, 50B50-HR machines more easily (48 vs 36 out of 100) and 50B50-QT540 forms better (45 vs 35 out of 100).
50B50-HRChoose it when the part is machined in volume.
50B50-QT540Choose it when strength drives the design, or when surface hardness matters.
50B50-HR vs 50B50-QT540: 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)
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 · Fracture Toughness (K_IC) 75 MPa·√m68.3 ksi·√in
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 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 46 W/m·K26.6 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 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
Formability (cold)
Same in both: Brazeability / Solderability 55 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.2 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.
50B50-HR vs 50B50-QT540 — frequently asked
Is 50B50-QT540 stronger than 50B50-HR?
Yes. 50B50-QT540 has a typical yield strength of 1,060 MPa (154 ksi) against 460 MPa (66.7 ksi) for 50B50-HR — about 130% more. Tensile strength is 1,150 MPa (167 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, HR or QT540?
A is the default 50B50 condition in the FabDigit quote flow (neither HR nor QT540). 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, 50B50-HR or 50B50-QT540?
50B50-HR, by a small margin. Both rate fair for machinability — 48/100 against 36/100 for 50B50-QT540.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 50B50-HR and 50B50-QT540 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.