Stainless Steel ER308Si vs ER320
Stainless Steel · grade comparison
Stainless Steel ER308Si and ER320 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 ER320, about 5% more. ER308Si is the more ductile: elongation 38% versus 34% for ER320. ER308Si runs hotter in service (760°C vs 500°C continuous) and ER308Si conducts heat better (15 W/m·K vs 12.6 W/m·K). On the shop floor, ER308Si machines more easily (fair vs poor), ER308Si welds better (excellent vs good), and ER308Si sits in a lower cost tier (premium, $$$) than ER320 (high, $$$$).
ER308SiChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
ER308Si vs ER320: 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
Shear Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Shear Strength 400 MPa58 ksi · Charpy V-Notch Impact (RT) 90 J66.4 ft·lbf · 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
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · 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
Brazeability / Solderability
Castability
Same in both: Formability (cold) 60 / 100 · Polishability 70 / 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)
Modulus of Resilience
Thermal Diffusivity
Same in both: 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 | ER308Si | ER320 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 7 finishes: Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Pickling, Plasma Spray, Silver Plating.
ER308Si vs ER320 — frequently asked
Is ER308Si stronger than ER320?
Yes. ER308Si has a typical yield strength of 400 MPa (58 ksi) against 380 MPa (55.1 ksi) for ER320 — about 5% more. Tensile strength is 600 MPa (87 ksi) vs 585 MPa (84.8 ksi).
Which is cheaper, ER308Si or ER320?
ER308Si is the lower-cost material: it sits in the premium tier ($$$) while ER320 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, ER308Si or ER320?
ER308Si. Its machinability rates fair (40/100) against poor (26/100) for ER320; for welding the order is ER308Si first (excellent, 95/100) then ER320 (good, 68/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ER308Si and ER320 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.