Steel 8720-HR vs 8720 QT-33-38HRC
Steel · 8720 temper comparison
8720-HR and 8720 QT-33-38HRC are two conditions of the same steel grade, 8720: HR (hot rolled) versus QT-33-38HRC. The chemistry is identical, so every difference below comes from the condition. 8720 QT-33-38HRC is the stronger of the two: yield strength 950 MPa (138 ksi) against 380 MPa (55.1 ksi) for 8720-HR, about 150% more; tensile strength follows at 1,120 MPa (162 ksi) vs 620 MPa (89.9 ksi). In exchange, 8720-HR is the more ductile: elongation 25% versus 15% for 8720 QT-33-38HRC, and 8720 QT-33-38HRC is harder (331 HB vs 179 HB). On the shop floor, 8720-HR machines more easily (good vs fair).
8720-HRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
8720 QT-33-38HRCChoose it when strength drives the design.
8720-HR vs 8720 QT-33-38HRC: 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
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
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,416°C2,581 °F · Liquidus Temperature 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 45 W/m·K26 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.6 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 350°C662 °F · Min Service Temperature -40°C-40 °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).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 65 / 100 · Brazeability / Solderability 60 / 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) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 35%
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.
8720-HR vs 8720 QT-33-38HRC — frequently asked
Is 8720 QT-33-38HRC stronger than 8720-HR?
Yes. 8720 QT-33-38HRC has a typical yield strength of 950 MPa (138 ksi) against 380 MPa (55.1 ksi) for 8720-HR — about 150% more. Tensile strength is 1,120 MPa (162 ksi) vs 620 MPa (89.9 ksi).
Which condition does FabDigit quote by default, HR or QT-33-38HRC?
ANN is the default 8720 condition in the FabDigit quote flow (neither HR nor QT-33-38HRC). 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, 8720-HR or 8720 QT-33-38HRC?
8720-HR. Its machinability rates good (60/100) against fair (35/100) for 8720 QT-33-38HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 8720-HR and 8720 QT-33-38HRC 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.