Stainless Steel 1.4317-QT780 vs 1.4317-QT900
Stainless Steel · 1.4317 temper comparison
1.4317-QT780 and 1.4317-QT900 are two conditions of the same stainless steel grade, 1.4317: QT780 versus QT900. The chemistry is identical, so every difference below comes from the condition. 1.4317-QT900 is the stronger of the two: yield strength 730 MPa (106 ksi) against 620 MPa (89.9 ksi) for 1.4317-QT780, about 18% more; tensile strength follows at 930 MPa (135 ksi) vs 830 MPa (120 ksi). In exchange, 1.4317-QT780 is the more ductile: elongation 18% versus 15% for 1.4317-QT900, and 1.4317-QT900 is harder (300 HB vs 260 HB). On the shop floor, 1.4317-QT780 welds better (very good vs good).
1.4317-QT780Choose it when the part is bent, formed or impact-loaded, or when it will be welded.
1.4317-QT900Choose it when strength drives the design.
1.4317-QT780 vs 1.4317-QT900: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3 · Compressive Strength 640 MPa92.8 ksi · Shear Strength 500 MPa72.5 ksi · Fracture Toughness (K_IC) 180 MPa·√m164 ksi·√in
Physical
Density and transition temperatures.
Same in both: Density 7.7 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 25 W/m·K14.4 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.5 µm/m·K5.8 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Max Service Temperature (continuous) 450°C842 °F · Min Service Temperature -100°C-148 °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).
Same in both: Galvanic Potential (seawater, vs SCE) -0.3 V · Corrosion Resistance 52 / 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) 15 / 100 · Castability 70 / 100 · Brazeability / Solderability 40 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 50 MJ/kg21,496 BTU/lb · Embodied Carbon (primary production) 3.6 kg CO₂/kg · Embodied Water 200 L/kg24 gal/lb · Typical Recycled Content 70%
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.
1.4317-QT780 vs 1.4317-QT900 — frequently asked
Is 1.4317-QT900 stronger than 1.4317-QT780?
Yes. 1.4317-QT900 has a typical yield strength of 730 MPa (106 ksi) against 620 MPa (89.9 ksi) for 1.4317-QT780 — about 18% more. Tensile strength is 930 MPa (135 ksi) vs 830 MPa (120 ksi).
Which condition does FabDigit quote by default, QT780 or QT900?
QT780 is the default 1.4317 condition in the FabDigit quote flow. 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, 1.4317-QT780 or 1.4317-QT900?
1.4317-QT780. Its machinability rates fair (40/100) against poor (33/100) for 1.4317-QT900; for welding the order is 1.4317-QT780 first (very good, 70/100) then 1.4317-QT900 (good, 60/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 1.4317-QT780 and 1.4317-QT900 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.