Stainless Steel 7Cr17-QT45 vs 7Cr17-QT56
Stainless Steel · 7Cr17 temper comparison
7Cr17-QT45 and 7Cr17-QT56 are two conditions of the same stainless steel grade, 7Cr17: QT45 (Q&T ~44–48 HRC) versus QT56 (Q&T 54–57 HRC). The chemistry is identical, so every difference below comes from the condition. 7Cr17-QT56 is the stronger of the two: yield strength 1,650 MPa (239 ksi) against 1,250 MPa (181 ksi) for 7Cr17-QT45, about 32% more; tensile strength follows at 1,850 MPa (268 ksi) vs 1,450 MPa (210 ksi). In exchange, 7Cr17-QT45 is the more ductile: elongation 8% versus 4% for 7Cr17-QT56, and 7Cr17-QT56 is harder (620 HV vs 460 HV). 7Cr17-QT45 runs hotter in service (250°C vs 175°C continuous).
7Cr17-QT45Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
7Cr17-QT56Choose it when strength drives the design.
7Cr17-QT45 vs 7Cr17-QT56: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless 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 stainless 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, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.28 · Compressive Strength 430 MPa62.4 ksi · Shear Strength 470 MPa68.2 ksi · Hardness, Brinell 220 HB · Hardness, Rockwell B 96 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.7 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,370°C2,498 °F · Liquidus Temperature 1,425°C2,597 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 24 W/m·K13.9 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.2 µm/m·K5.7 µin/in·°F · Latent Heat of Fusion 260 J/g112 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 2.9 % IACS · Electrical Resistivity 6×10⁻⁷ Ω·m23.6 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.3 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Same in both: Machinability Rating (AISI 1212 = 100 %) 45% · Weldability 20 / 100 · Formability (cold) 30 / 100 · Castability 35 / 100 · Brazeability / Solderability 45 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 45 MJ/kg19,347 BTU/lb · Embodied Carbon (primary production) 3.5 kg CO₂/kg · Embodied Water 130 L/kg15.6 gal/lb · Typical Recycled Content 50%
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
7Cr17-QT45 vs 7Cr17-QT56 — frequently asked
Is 7Cr17-QT56 stronger than 7Cr17-QT45?
Yes. 7Cr17-QT56 has a typical yield strength of 1,650 MPa (239 ksi) against 1,250 MPa (181 ksi) for 7Cr17-QT45 — about 32% more. Tensile strength is 1,850 MPa (268 ksi) vs 1,450 MPa (210 ksi).
Which condition does FabDigit quote by default, QT45 or QT56?
A is the default 7Cr17 condition in the FabDigit quote flow (neither QT45 nor QT56). 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, 7Cr17-QT45 or 7Cr17-QT56?
7Cr17-QT45. Its machinability rates poor (15/100) against not recommended (6/100) for 7Cr17-QT56.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 7Cr17-QT45 and 7Cr17-QT56 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.