Stainless Steel 1.3940 vs CD4MCuN
Stainless Steel · grade comparison
Stainless Steel 1.3940 and CD4MCuN are both stainless steel grades. CD4MCuN 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 730 MPa (106 ksi) vs 530 MPa (76.9 ksi). In exchange, 1.3940 is the more ductile: elongation 55% versus 25% for CD4MCuN, and CD4MCuN is harder (250 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) and 1.3940 welds better (excellent vs good).
1.3940Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
CD4MCuNChoose it when strength drives the design.
1.3940 vs CD4MCuN: 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
Bulk 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 · 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 Carbon (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 53 MJ/kg22,786 BTU/lb
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 | CD4MCuN |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$ Premium |
| 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 CD4MCuN — frequently asked
Is CD4MCuN stronger than 1.3940?
Yes. CD4MCuN 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 730 MPa (106 ksi) vs 530 MPa (76.9 ksi).
Which is cheaper, 1.3940 or CD4MCuN?
Both sit in the same relative cost tier ($$$, premium); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, 1.3940 or CD4MCuN?
1.3940. Its machinability rates fair (40/100) against poor (30/100) for CD4MCuN; for welding the order is 1.3940 first (excellent, 88/100) then CD4MCuN (good, 55/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 1.3940 and CD4MCuN 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.