Steel X7Ni9 +A vs X7Ni9 +NNT
Steel · X7Ni9 temper comparison
X7Ni9 +A and X7Ni9 +NNT are two conditions of the same steel grade, X7Ni9: +A (annealed) versus +NNT (double normalized and tempered). The chemistry is identical, so every difference below comes from the condition. X7Ni9 +NNT is the stronger of the two: yield strength 570 MPa (82.7 ksi) against 450 MPa (65.3 ksi) for X7Ni9 +A, about 27% more; tensile strength follows at 720 MPa (104 ksi) vs 640 MPa (92.8 ksi). In exchange, X7Ni9 +A is the more ductile: elongation 28% versus 25% for X7Ni9 +NNT, and X7Ni9 +NNT is harder (205 HB vs 180 HB).
X7Ni9 +AChoose it when the part is bent, formed or impact-loaded.
X7Ni9 +NNTChoose it when strength drives the design.
X7Ni9 +A vs X7Ni9 +NNT: 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)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 195 GPa28.3 Msi · Shear Modulus 76 GPa11 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,430°C2,606 °F · Liquidus Temperature 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 30 W/m·K17.3 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 270 J/g116 BTU/lb · Max Service Temperature (continuous) 350°C662 °F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3.8 % IACS · Electrical Resistivity 4.5×10⁻⁷ Ω·m17.7 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 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
Formability (cold)
Same in both: Brazeability / Solderability 40 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 40 MJ/kg17,197 BTU/lb · Embodied Carbon (primary production) 3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 25%
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.
X7Ni9 +A vs X7Ni9 +NNT — frequently asked
Is X7Ni9 +NNT stronger than X7Ni9 +A?
Yes. X7Ni9 +NNT has a typical yield strength of 570 MPa (82.7 ksi) against 450 MPa (65.3 ksi) for X7Ni9 +A — about 27% more. Tensile strength is 720 MPa (104 ksi) vs 640 MPa (92.8 ksi).
Which condition does FabDigit quote by default, +A or +NNT?
+QT is the default X7Ni9 condition in the FabDigit quote flow (neither +A nor +NNT). 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, X7Ni9 +A or X7Ni9 +NNT?
X7Ni9 +A, by a small margin. Both rate fair for machinability — 50/100 against 42/100 for X7Ni9 +NNT; for welding the order is X7Ni9 +A first (good, 60/100) then X7Ni9 +NNT (good, 55/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in X7Ni9 +A and X7Ni9 +NNT 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.