Steel ZG340-640 N+T vs ZG340-640 Q&T
Steel · ZG340-640 temper comparison
ZG340-640 N+T and ZG340-640 Q&T are two conditions of the same steel grade, ZG340-640: N+T (normalized and tempered) versus Q&T (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. ZG340-640 Q&T is the stronger of the two: yield strength 550 MPa (79.8 ksi) against 370 MPa (53.7 ksi) for ZG340-640 N+T, about 49% more; tensile strength follows at 800 MPa (116 ksi) vs 670 MPa (97.2 ksi). ZG340-640 Q&T is harder — 260 HB against 215 HB for ZG340-640 N+T — which matters for wear surfaces and threads. On the shop floor, ZG340-640 N+T machines more easily (51 vs 40 out of 100).
ZG340-640 N+TChoose it when the part is machined in volume.
ZG340-640 Q&TChoose it when strength drives the design, or when surface hardness matters.
ZG340-640 N+T vs ZG340-640 Q&T: 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, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 79 GPa11.5 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.82 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.
Same in both: Thermal Conductivity 45 W/m·K26 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.2 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 8.6 % IACS · Electrical Resistivity 2×10⁻⁷ Ω·m7.87 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.62 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
Formability (cold)
Same in both: Castability 55 / 100 · Brazeability / Solderability 55 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 24 MJ/kg10,318 BTU/lb · Embodied Carbon (primary production) 2 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 80%
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.
ZG340-640 N+T vs ZG340-640 Q&T — frequently asked
Is ZG340-640 Q&T stronger than ZG340-640 N+T?
Yes. ZG340-640 Q&T has a typical yield strength of 550 MPa (79.8 ksi) against 370 MPa (53.7 ksi) for ZG340-640 N+T — about 49% more. Tensile strength is 800 MPa (116 ksi) vs 670 MPa (97.2 ksi).
Which condition does FabDigit quote by default, N+T or Q&T?
Normalized is the default ZG340-640 condition in the FabDigit quote flow (neither N+T nor Q&T). 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, ZG340-640 N+T or ZG340-640 Q&T?
ZG340-640 N+T, by a small margin. Both rate fair for machinability — 51/100 against 40/100 for ZG340-640 Q&T; for welding the order is ZG340-640 N+T first (fair, 35/100) then ZG340-640 Q&T (poor, 28/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ZG340-640 N+T and ZG340-640 Q&T 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.