Stainless Steel ER308Si vs ER347
Stainless Steel · grade comparison
Stainless Steel ER308Si and ER347 are both stainless steel grades. Both yield at about 400 MPa — strength does not separate them. On the shop floor, ER308Si forms better (good vs fair) and ER308Si sits in a lower cost tier (premium, $$$) than ER347 (high, $$$$).
ER308SiChoose it when cost is the deciding factor.
ER308Si vs ER347: 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.
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Rockwell B
Same in both: Elastic (Young's) Modulus 195 GPa28.3 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Elongation at Break 38% · Fracture Toughness (K_IC) 140 MPa·√m127 ksi·√in · Hardness, Brinell 175 HB · Hardness, Vickers 185 HV
Physical
Density and transition temperatures.
Same in both: Density 7.95 g/cm³0.29 lb/in³ · 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 Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Same in both: Electrical Conductivity 2.4 % IACS
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
Same in both: Brazeability / Solderability 60 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 5.5 kg CO₂/kg
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Specific Stiffness (E / density) 24.5 MN·m/kg · 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 | ER347 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 7 finishes: Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Pickling, Plasma Spray, Silver Plating.
ER308Si vs ER347 — frequently asked
What is the difference between ER308Si and ER347?
Stainless Steel ER308Si and ER347 are both stainless steel grades. Both yield at about 400 MPa — strength does not separate them. On the shop floor, ER308Si forms better (good vs fair) and ER308Si sits in a lower cost tier (premium, $$$) than ER347 (high, $$$$).
Which is cheaper, ER308Si or ER347?
ER308Si is the lower-cost material: it sits in the premium tier ($$$) while ER347 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 ER347?
ER308Si, by a small margin. Both rate fair for machinability — 40/100 against 35/100 for ER347; for welding the order is ER308Si first (excellent, 95/100) then ER347 (excellent, 88/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ER308Si and ER347 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.