Stainless Steel E308LMo vs ER308Si
Stainless Steel · grade comparison
Stainless Steel E308LMo and ER308Si are both stainless steel grades. ER308Si is the stronger of the two: tensile strength 600 MPa (87 ksi) against 560 MPa (81.2 ksi) for E308LMo, about 7% more. ER308Si runs hotter in service (760°C vs 400°C continuous). On the shop floor, ER308Si sits in a lower cost tier (premium, $$$) than E308LMo (high, $$$$).
ER308SiChoose it when strength drives the design, or when the part sees heat.
E308LMo 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.
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 195 GPa28.3 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 400 MPa58 ksi · Reduction in Area 55% · Compressive Strength 400 MPa58 ksi
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.
Max Service Temperature (continuous)
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 · Thermal Expansion (CTE, 20–100 °C) 16.5 µm/m·K9.2 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -196°C-321 °F
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
Same in both: Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Energy (primary production) 55 MJ/kg23,646 BTU/lb
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 | E308LMo | ER308Si |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$ 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.
E308LMo vs ER308Si — frequently asked
Is ER308Si stronger than E308LMo?
Yes. ER308Si has a typical tensile strength of 600 MPa (87 ksi) against 560 MPa (81.2 ksi) for E308LMo — about 7% more.
Which is cheaper, E308LMo or ER308Si?
ER308Si is the lower-cost material: it sits in the premium tier ($$$) while E308LMo is high ($$$$). 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, E308LMo or ER308Si?
ER308Si, by a small margin. Both rate fair for machinability — 40/100 against 35/100 for E308LMo; for welding the order is ER308Si first (excellent, 95/100) then E308LMo (excellent, 90/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in E308LMo 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.