Steel 18MnMoNi5-5-A vs 18MnMoNi5-5 QT+SPWHT
Steel · 18MnMoNi5-5 temper comparison
18MnMoNi5-5-A and 18MnMoNi5-5 QT+SPWHT are two conditions of the same steel grade, 18MnMoNi5-5: A (solution annealed) versus QT+SPWHT (QT + simulated post-weld heat treatment). The chemistry is identical, so every difference below comes from the condition. 18MnMoNi5-5 QT+SPWHT is the stronger of the two: yield strength 440 MPa (63.8 ksi) against 320 MPa (46.4 ksi) for 18MnMoNi5-5-A, about 38% more; tensile strength follows at 590 MPa (85.6 ksi) vs 520 MPa (75.4 ksi). In exchange, 18MnMoNi5-5-A is the more ductile: elongation 26% versus 23% for 18MnMoNi5-5 QT+SPWHT, and 18MnMoNi5-5 QT+SPWHT is harder (185 HB vs 160 HB). 18MnMoNi5-5 QT+SPWHT runs hotter in service (400°C vs 350°C continuous).
18MnMoNi5-5-AChoose it when the part is bent, formed or impact-loaded.
18MnMoNi5-5 QT+SPWHTChoose it when strength drives the design, or when the part sees heat.
18MnMoNi5-5-A vs 18MnMoNi5-5 QT+SPWHT: 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.
18MnMoNi5-5-A18MnMoNi5-5 QT+SPWHT
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
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: Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 62%
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,460°C2,660 °F · Liquidus Temperature 1,510°C2,750 °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 270 J/g116 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 13 / 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 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 20%
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.
18MnMoNi5-5-A vs 18MnMoNi5-5 QT+SPWHT — frequently asked
Is 18MnMoNi5-5 QT+SPWHT stronger than 18MnMoNi5-5-A?
Yes. 18MnMoNi5-5 QT+SPWHT has a typical yield strength of 440 MPa (63.8 ksi) against 320 MPa (46.4 ksi) for 18MnMoNi5-5-A — about 38% more. Tensile strength is 590 MPa (85.6 ksi) vs 520 MPa (75.4 ksi).
Which condition does FabDigit quote by default, A or QT+SPWHT?
QT is the default 18MnMoNi5-5 condition in the FabDigit quote flow (neither A nor QT+SPWHT). 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, 18MnMoNi5-5-A or 18MnMoNi5-5 QT+SPWHT?
18MnMoNi5-5-A, by a small margin. Both rate good for machinability — 65/100 against 58/100 for 18MnMoNi5-5 QT+SPWHT; for welding the order is 18MnMoNi5-5-A first (very good, 70/100) then 18MnMoNi5-5 QT+SPWHT (good, 65/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18MnMoNi5-5-A and 18MnMoNi5-5 QT+SPWHT 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.