Steel 1055-QT205 vs 1055-QT425
Steel · 1055 temper comparison
1055-QT205 and 1055-QT425 are two conditions of the same steel grade, 1055: QT205 (Q&T 205 °C) versus QT425 (Q&T 425 °C). The chemistry is identical, so every difference below comes from the condition. 1055-QT205 is the stronger of the two: yield strength 880 MPa (128 ksi) against 740 MPa (107 ksi) for 1055-QT425, about 19% more; tensile strength follows at 1,240 MPa (180 ksi) vs 965 MPa (140 ksi). In exchange, 1055-QT425 is the more ductile: elongation 15% versus 8% for 1055-QT205, and 1055-QT205 is harder (514 HB vs 340 HB). 1055-QT425 runs hotter in service (350°C vs 150°C continuous). On the shop floor, 1055-QT425 machines more easily (30 vs 15 out of 100) and 1055-QT425 welds better (poor vs not recommended).
1055-QT205Choose it when strength drives the design.
1055-QT425Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
1055-QT205 vs 1055-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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
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 · Compressive Strength 370 MPa53.7 ksi · Shear Strength 400 MPa58 ksi · Hardness, Rockwell B 92 HRB
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 1,490°C2,714 °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) 11.7 µm/m·K6.5 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 9.5 % IACS · Electrical Resistivity 1.8×10⁻⁷ Ω·m7.09 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 10 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Same in both: Formability (cold) 35 / 100 · Castability 40 / 100 · Brazeability / Solderability 60 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 26 MJ/kg11,178 BTU/lb · Embodied Carbon (primary production) 2 kg CO₂/kg · Embodied Water 50 L/kg6 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.
1055-QT205 vs 1055-QT425 — frequently asked
Is 1055-QT205 stronger than 1055-QT425?
Yes. 1055-QT205 has a typical yield strength of 880 MPa (128 ksi) against 740 MPa (107 ksi) for 1055-QT425 — about 19% more. Tensile strength is 1,240 MPa (180 ksi) vs 965 MPa (140 ksi).
Which condition does FabDigit quote by default, QT205 or QT425?
HR is the default 1055 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, 1055-QT205 or 1055-QT425?
1055-QT425, by a small margin. Both rate poor for machinability — 30/100 against 15/100 for 1055-QT205; for welding the order is 1055-QT425 first (poor, 28/100) then 1055-QT205 (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 1055-QT205 and 1055-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.