Steel 18Ni(400)-CD vs 18Ni(400) Overaged
Steel · 18Ni(400) temper comparison
18Ni(400)-CD and 18Ni(400) Overaged are two conditions of the same steel grade, 18Ni(400): CD (cold drawn) versus Overaged (aged 510–540 °C for improved toughness). The chemistry is identical, so every difference below comes from the condition. 18Ni(400) Overaged is the stronger of the two: yield strength 2,350 MPa (341 ksi) against 1,250 MPa (181 ksi) for 18Ni(400)-CD, about 88% more; tensile strength follows at 2,450 MPa (355 ksi) vs 1,400 MPa (203 ksi). 18Ni(400) Overaged is the more ductile: elongation 8% versus 6% for 18Ni(400)-CD, and 18Ni(400) Overaged is harder (54 HRC vs 40 HRC). 18Ni(400) Overaged is stiffer (200 GPa vs 190 GPa) and 18Ni(400) Overaged runs hotter in service (425°C vs 250°C continuous). On the shop floor, 18Ni(400)-CD machines more easily (32 vs 22 out of 100).
18Ni(400)-CDChoose it when the part is machined in volume.
18Ni(400) OveragedChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
18Ni(400)-CD vs 18Ni(400) Overaged: 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.
18Ni(400)-CD18Ni(400) Overaged
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
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, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Same in both: Density 8.1 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,440°C2,624 °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 450 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.1 µm/m·K5.6 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -73°C-99 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.55 V · Corrosion Resistance 25 / 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 35 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 90 MJ/kg38,693 BTU/lb · Embodied Carbon (primary production) 6.5 kg CO₂/kg · Embodied Water 110 L/kg13.2 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.
18Ni(400)-CD vs 18Ni(400) Overaged — frequently asked
Is 18Ni(400) Overaged stronger than 18Ni(400)-CD?
Yes. 18Ni(400) Overaged has a typical yield strength of 2,350 MPa (341 ksi) against 1,250 MPa (181 ksi) for 18Ni(400)-CD — about 88% more. Tensile strength is 2,450 MPa (355 ksi) vs 1,400 MPa (203 ksi).
Which condition does FabDigit quote by default, CD or Overaged?
Aged is the default 18Ni(400) condition in the FabDigit quote flow (neither CD nor Overaged). 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, 18Ni(400)-CD or 18Ni(400) Overaged?
18Ni(400)-CD, by a small margin. Both rate poor for machinability — 32/100 against 22/100 for 18Ni(400) Overaged; for welding the order is 18Ni(400)-CD first (very good, 75/100) then 18Ni(400) Overaged (very good, 70/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18Ni(400)-CD and 18Ni(400) Overaged 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.