Steel 18Ni(400)-CD vs 18Ni(400)-SA
Steel · 18Ni(400) temper comparison
18Ni(400)-CD and 18Ni(400)-SA are two conditions of the same steel grade, 18Ni(400): CD (cold drawn) versus SA (solution annealed). The chemistry is identical, so every difference below comes from the condition. 18Ni(400)-CD is the stronger of the two: yield strength 1,250 MPa (181 ksi) against 900 MPa (131 ksi) for 18Ni(400)-SA, about 39% more; tensile strength follows at 1,400 MPa (203 ksi) vs 1,170 MPa (170 ksi). In exchange, 18Ni(400)-SA is the more ductile: elongation 12% versus 6% for 18Ni(400)-CD, and 18Ni(400)-CD is harder (40 HRC vs 33 HRC). 18Ni(400)-SA is stiffer (200 GPa vs 190 GPa) and 18Ni(400)-SA runs hotter in service (400°C vs 250°C continuous).
18Ni(400)-CDChoose it when strength drives the design.
18Ni(400)-SAChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
18Ni(400)-CD vs 18Ni(400)-SA: 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.
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)
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 · Fracture Toughness (K_IC) 90 MPa·√m81.9 ksi·√in
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 %)
Formability (cold)
Same in both: Weldability 75 / 100 · 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)-SA — frequently asked
Is 18Ni(400)-CD stronger than 18Ni(400)-SA?
Yes. 18Ni(400)-CD has a typical yield strength of 1,250 MPa (181 ksi) against 900 MPa (131 ksi) for 18Ni(400)-SA — about 39% more. Tensile strength is 1,400 MPa (203 ksi) vs 1,170 MPa (170 ksi).
Which condition does FabDigit quote by default, CD or SA?
Aged is the default 18Ni(400) condition in the FabDigit quote flow (neither CD nor SA). 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)-SA?
18Ni(400)-SA. Its machinability rates fair (40/100) against poor (32/100) for 18Ni(400)-CD.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18Ni(400)-CD and 18Ni(400)-SA 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.