Stainless Steel 1.3940 vs CD3MCuN
Stainless Steel · grade comparison
Stainless Steel 1.3940 and CD3MCuN are both stainless steel grades. CD3MCuN is the stronger of the two: yield strength 550 MPa (79.8 ksi) against 250 MPa (36.3 ksi) for 1.3940, about 120% more; tensile strength follows at 740 MPa (107 ksi) vs 530 MPa (76.9 ksi). In exchange, 1.3940 is the more ductile: elongation 55% versus 32% for CD3MCuN, and CD3MCuN is harder (230 HB vs 140 HB). 1.3940 runs hotter in service (425°C vs 300°C continuous). On the shop floor, 1.3940 machines more easily (fair vs poor), 1.3940 welds better (excellent vs good), and 1.3940 sits in a lower cost tier (premium, $$$) than CD3MCuN (high, $$$$).
1.3940Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
CD3MCuNChoose it when strength drives the design.
1.3940 vs CD3MCuN: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless 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 stainless 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
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Compressive Strength
Hardness, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Melting Point (Solidus)
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Liquidus Temperature 1,450°C2,642 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Latent Heat of Fusion 270 J/g116 BTU/lb
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 1.3940 | CD3MCuN |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 7 finishes: Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Pickling, Plasma Spray, Silver Plating.
1.3940 vs CD3MCuN — frequently asked
Is CD3MCuN stronger than 1.3940?
Yes. CD3MCuN has a typical yield strength of 550 MPa (79.8 ksi) against 250 MPa (36.3 ksi) for 1.3940 — about 120% more. Tensile strength is 740 MPa (107 ksi) vs 530 MPa (76.9 ksi).
Which is cheaper, 1.3940 or CD3MCuN?
1.3940 is the lower-cost material: it sits in the premium tier ($$$) while CD3MCuN is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, 1.3940 or CD3MCuN?
1.3940. Its machinability rates fair (40/100) against poor (30/100) for CD3MCuN; for welding the order is 1.3940 first (excellent, 88/100) then CD3MCuN (good, 62/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 1.3940 and CD3MCuN 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.