Stainless Steel E309L vs ER308Si
Stainless Steel · grade comparison
Stainless Steel E309L and ER308Si are both stainless steel grades. ER308Si is the stronger of the two: tensile strength 600 MPa (87 ksi) against 570 MPa (82.7 ksi) for E309L, about 5% more. E309L is harder — 190 HB against 175 HB for ER308Si — which matters for wear surfaces and threads.
E309LChoose it when surface hardness matters.
ER308SiChoose it when strength drives the design.
E309L 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.
Bulk Modulus
Tensile Strength (Ultimate)
Reduction in Area
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 195 GPa28.3 Msi · Shear Modulus 77 GPa11.2 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 400 MPa58 ksi · Elongation at Break 38% · Compressive Strength 400 MPa58 ksi · Shear Strength 400 MPa58 ksi · Fatigue Strength (Endurance Limit) 240 MPa34.8 ksi · Hardness, Rockwell B 88 HRB
Physical
Density and transition temperatures.
Density
Same in both: Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,450°C2,642 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Thermal Conductivity 15 W/m·K8.7 BTU/hr·ft·°F · Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · 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)
Same in both: Corrosion Resistance 68 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability Rating (AISI 1212 = 100 %)
Weldability
Brazeability / Solderability
Polishability
Formability (cold)
Same in both: Machinability 40 / 100
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)
Same in both: Modulus of Resilience 410 kJ/m³ · Thermal Diffusivity 3.8 mm²/s · Thermal Shock Resistance Index 3
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 | E309L | 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.
E309L vs ER308Si — frequently asked
Is ER308Si stronger than E309L?
Yes. ER308Si has a typical tensile strength of 600 MPa (87 ksi) against 570 MPa (82.7 ksi) for E309L — about 5% more.
Which is cheaper, E309L 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 welds better, E309L or ER308Si?
ER308Si. Its weldability rates excellent (95/100) against excellent (90/100) for E309L.
Ready to make it?
Upload a CAD file and FabDigit prices the part in E309L 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.