Steel Ductile Iron Q&T vs Ductile Iron Stress Relieved
Steel · Ductile Iron temper comparison
Ductile Iron Q&T and Ductile Iron Stress Relieved are two conditions of the same steel grade, Ductile Iron: Q&T (quenched and tempered) versus Stress Relieved. The chemistry is identical, so every difference below comes from the condition. Ductile Iron Q&T is the stronger of the two: yield strength 700 MPa (102 ksi) against 320 MPa (46.4 ksi) for Ductile Iron Stress Relieved, about 119% more; tensile strength follows at 900 MPa (131 ksi) vs 460 MPa (66.7 ksi). In exchange, Ductile Iron Stress Relieved is the more ductile: elongation 15% versus 3% for Ductile Iron Q&T, and Ductile Iron Q&T is harder (320 HB vs 180 HB). Ductile Iron Stress Relieved runs hotter in service (400°C vs 300°C continuous) and Ductile Iron Stress Relieved conducts heat better (33 W/m·K vs 26 W/m·K). On the shop floor, Ductile Iron Stress Relieved machines more easily (very good vs fair) and Ductile Iron Stress Relieved welds better (fair vs poor).
Ductile Iron Q&TChoose it when strength drives the design.
Ductile Iron Stress RelievedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
Ductile Iron Q&T vs Ductile Iron Stress Relieved: 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.
Ductile Iron Q&TDuctile Iron Stress Relieved
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)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Same in both: Elastic (Young's) Modulus 169 GPa24.5 Msi · Shear Modulus 65 GPa9.4 Msi · Bulk Modulus 130 GPa18.9 Msi · Poisson's Ratio 0.28
Physical
Density and transition temperatures.
Same in both: Density 7.1 g/cm³0.26 lb/in³ · Melting Point (Solidus) 1,150°C2,102 °F · Liquidus Temperature 1,175°C2,147 °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 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12 µm/m·K6.7 µin/in·°F · Latent Heat of Fusion 220 J/g94.6 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3.1 % IACS · Electrical Resistivity 5.6×10⁻⁷ Ω·m22 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 16 / 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) 8 / 100 · Castability 88 / 100 · Brazeability / Solderability 40 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 21 MJ/kg9,028 BTU/lb · Embodied Carbon (primary production) 1.9 kg CO₂/kg · Embodied Water 40 L/kg4.8 gal/lb · Typical Recycled Content 85%
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.
Ductile Iron Q&T vs Ductile Iron Stress Relieved — frequently asked
Is Ductile Iron Q&T stronger than Ductile Iron Stress Relieved?
Yes. Ductile Iron Q&T has a typical yield strength of 700 MPa (102 ksi) against 320 MPa (46.4 ksi) for Ductile Iron Stress Relieved — about 119% more. Tensile strength is 900 MPa (131 ksi) vs 460 MPa (66.7 ksi).
Which condition does FabDigit quote by default, Q&T or Stress Relieved?
As Cast is the default Ductile Iron condition in the FabDigit quote flow (neither Q&T nor Stress Relieved). 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, Ductile Iron Q&T or Ductile Iron Stress Relieved?
Ductile Iron Stress Relieved. Its machinability rates very good (70/100) against fair (38/100) for Ductile Iron Q&T; for welding the order is Ductile Iron Stress Relieved first (fair, 38/100) then Ductile Iron Q&T (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Ductile Iron Q&T and Ductile Iron Stress Relieved 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.