Stainless Steel E409Nb vs ER308Si
Stainless Steel · grade comparison
Stainless Steel E409Nb and ER308Si are both stainless steel grades. ER308Si is the stronger of the two: yield strength 400 MPa (58 ksi) against 380 MPa (55.1 ksi) for E409Nb, about 5% more; tensile strength follows at 600 MPa (87 ksi) vs 500 MPa (72.5 ksi). ER308Si is the more ductile: elongation 38% versus 22% for E409Nb. E409Nb is lighter (7.7 g/cm³ vs 7.95 g/cm³ for ER308Si) and ER308Si runs hotter in service (760°C vs 675°C continuous). On the shop floor, ER308Si welds better (excellent vs very good).
E409NbChoose it when weight is the constraint.
ER308SiChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
E409Nb vs ER308Si: 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
Poisson's Ratio
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, Brinell
Hardness, Vickers
Same in both: Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Hardness, Rockwell B 88 HRB
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
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)
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 | E409Nb | ER308Si |
|---|---|---|
| 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.
E409Nb vs ER308Si — frequently asked
Is ER308Si stronger than E409Nb?
Yes. ER308Si has a typical yield strength of 400 MPa (58 ksi) against 380 MPa (55.1 ksi) for E409Nb — about 5% more. Tensile strength is 600 MPa (87 ksi) vs 500 MPa (72.5 ksi).
Which is cheaper, E409Nb or ER308Si?
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, E409Nb or ER308Si?
E409Nb, by a small margin. Both rate fair for machinability — 48/100 against 40/100 for ER308Si; for welding the order is ER308Si first (excellent, 95/100) then E409Nb (very good, 70/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in E409Nb and ER308Si 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.