Steel 4118-HR vs 4118 QT-25HRC
Steel · 4118 temper comparison
4118-HR and 4118 QT-25HRC are two conditions of the same steel grade, 4118: HR (hot rolled) versus QT-25HRC (Q&T). The chemistry is identical, so every difference below comes from the condition. 4118 QT-25HRC is the stronger of the two: yield strength 660 MPa (95.7 ksi) against 380 MPa (55.1 ksi) for 4118-HR, about 74% more; tensile strength follows at 860 MPa (125 ksi) vs 570 MPa (82.7 ksi). In exchange, 4118-HR is the more ductile: elongation 24% versus 18% for 4118 QT-25HRC, and 4118 QT-25HRC is harder (255 HB vs 163 HB). On the shop floor, 4118-HR machines more easily (good vs fair).
4118-HRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
4118 QT-25HRCChoose it when strength drives the design.
4118-HR vs 4118 QT-25HRC: 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 · Fracture Toughness (K_IC) 95 MPa·√m86.5 ksi·√in
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 1,505°C2,741 °F
Thermal
How each material carries heat and how hot it can run.
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 247 J/g106 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -40°C-40 °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) -0.62 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 %)
Formability (cold)
Same in both: Weldability 60 / 100 · Brazeability / Solderability 60 / 100 · Polishability 50 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 24 MJ/kg10,318 BTU/lb · Embodied Carbon (primary production) 1.9 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.
4118-HR vs 4118 QT-25HRC — frequently asked
Is 4118 QT-25HRC stronger than 4118-HR?
Yes. 4118 QT-25HRC has a typical yield strength of 660 MPa (95.7 ksi) against 380 MPa (55.1 ksi) for 4118-HR — about 74% more. Tensile strength is 860 MPa (125 ksi) vs 570 MPa (82.7 ksi).
Which condition does FabDigit quote by default, HR or QT-25HRC?
ANN is the default 4118 condition in the FabDigit quote flow (neither HR nor QT-25HRC). 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, 4118-HR or 4118 QT-25HRC?
4118-HR. Its machinability rates good (56/100) against fair (46/100) for 4118 QT-25HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4118-HR and 4118 QT-25HRC 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.