Steel 4068-QT205 vs 4068-QT425
Steel · 4068 temper comparison
4068-QT205 and 4068-QT425 are two conditions of the same steel grade, 4068: QT205 (oil quenched and tempered at 205 °C) versus QT425 (oil quenched and tempered at 425 °C). The chemistry is identical, so every difference below comes from the condition. 4068-QT205 is the stronger of the two: yield strength 1,650 MPa (239 ksi) against 1,350 MPa (196 ksi) for 4068-QT425, about 22% more; tensile strength follows at 2,100 MPa (305 ksi) vs 1,550 MPa (225 ksi). In exchange, 4068-QT425 is the more ductile: elongation 10% versus 5% for 4068-QT205, and 4068-QT205 is harder (601 HB vs 434 HB). 4068-QT425 runs hotter in service (330°C vs 150°C continuous) and 4068-QT425 conducts heat better (42 W/m·K vs 35 W/m·K). On the shop floor, 4068-QT425 machines more easily (poor vs not recommended).
4068-QT205Choose it when strength drives the design.
4068-QT425Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
4068-QT205 vs 4068-QT425: 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, 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 · Hardness, Rockwell B 94 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,470°C2,678 °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 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.5 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -20°C-4 °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) -0.61 V · Corrosion Resistance 11 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Same in both: Weldability 12 / 100 · Formability (cold) 30 / 100 · Brazeability / Solderability 45 / 100 · Polishability 65 / 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.
4068-QT205 vs 4068-QT425 — frequently asked
Is 4068-QT205 stronger than 4068-QT425?
Yes. 4068-QT205 has a typical yield strength of 1,650 MPa (239 ksi) against 1,350 MPa (196 ksi) for 4068-QT425 — about 22% more. Tensile strength is 2,100 MPa (305 ksi) vs 1,550 MPa (225 ksi).
Which condition does FabDigit quote by default, QT205 or QT425?
A is the default 4068 condition in the FabDigit quote flow (neither QT205 nor QT425). 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, 4068-QT205 or 4068-QT425?
4068-QT425. Its machinability rates poor (18/100) against not recommended (8/100) for 4068-QT205.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4068-QT205 and 4068-QT425 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.