Steel 4718-HR vs 4718 QT-30-34HRC
Steel · 4718 temper comparison
4718-HR and 4718 QT-30-34HRC are two conditions of the same steel grade, 4718: HR (hot rolled) versus QT-30-34HRC. The chemistry is identical, so every difference below comes from the condition. 4718 QT-30-34HRC is the stronger of the two: yield strength 830 MPa (120 ksi) against 460 MPa (66.7 ksi) for 4718-HR, about 80% more; tensile strength follows at 1,000 MPa (145 ksi) vs 700 MPa (102 ksi). In exchange, 4718-HR is the more ductile: elongation 22% versus 17% for 4718 QT-30-34HRC, and 4718 QT-30-34HRC is harder (302 HB vs 207 HB). 4718 QT-30-34HRC runs hotter in service (300°C vs 200°C continuous). On the shop floor, 4718-HR machines more easily (50 vs 40 out of 100) and 4718-HR welds better (fair vs poor).
4718-HRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
4718 QT-30-34HRCChoose it when strength drives the design, or when the part sees heat.
4718-HR vs 4718 QT-30-34HRC: 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)
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) 1,420°C2,588 °F · Liquidus Temperature 1,495°C2,723 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 42 W/m·K24.3 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.2 µm/m·K6.8 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 7.8 % 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) -0.61 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) 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.
4718-HR vs 4718 QT-30-34HRC — frequently asked
Is 4718 QT-30-34HRC stronger than 4718-HR?
Yes. 4718 QT-30-34HRC has a typical yield strength of 830 MPa (120 ksi) against 460 MPa (66.7 ksi) for 4718-HR — about 80% more. Tensile strength is 1,000 MPa (145 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, HR or QT-30-34HRC?
A is the default 4718 condition in the FabDigit quote flow (neither HR nor QT-30-34HRC). 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, 4718-HR or 4718 QT-30-34HRC?
4718-HR, by a small margin. Both rate fair for machinability — 50/100 against 40/100 for 4718 QT-30-34HRC; for welding the order is 4718-HR first (fair, 45/100) then 4718 QT-30-34HRC (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4718-HR and 4718 QT-30-34HRC 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.