Stainless Steel ER308Si
UNS S30880
ER308Si (UNS S30880) is a high-silicon version of ER308 austenitic stainless filler wire, with the added silicon improving arc wetting and weld pool fluidity.
Reference datasheet — ER308Si is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AW condition
ER308Si tempers and conditions
ER308Si is supplied in 4 conditions, soft to hard. AW is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution Annealed | Specify when the whole fabrication is solution treated at 1040–1100 °C and water quenched: δ-ferrite mostly dissolves, yield falls to 260 MPa, elongation rises to 50 % with better intergranular corrosion resistance. | 260 | 550 | 50 | 150 HB | 2.4 % IACS |
As Welded (SAW) | Use φ2.0–4.0 mm submerged-arc wire for thick-wall vessels and overlay; high heat input leaves 380 MPa yield and 36 % elongation, with ferrite level and toughness set by the neutral flux pairing. | 380 | 580 | 36 | 172 HB | 2.4 % IACS |
As Welded (GTAW) | Pick φ1.6–3.2 mm, 1000 mm straight lengths for pure-argon TIG root runs and thin sheet; low heat input and less oxidation give 40 % elongation, slightly tougher than the MIG deposit. | 390 | 590 | 40 | 165 HB | 2.4 % IACS |
AWDefault As-welded deposit | Choose as the standard supply and qualification state: φ0.8–1.6 mm spooled solid wire for MIG/MAG under Ar+2%O₂ or Ar+CO₂, used as welded at 400 MPa yield and 600 MPa tensile. | 400 | 600 | 38 | 175 HB | 2.4 % IACS |
Supply forms, finishes and certifications
Ways ER308Si is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CD-WIRE | Cold Drawn Wire | Supply form |
What is ER308Si?
ER308Si (UNS S30880) is a high-silicon version of ER308 austenitic stainless filler wire, with the added silicon improving arc wetting and weld pool fluidity. It is chosen for GMAW of 304-type stainless where flat, well-wetted beads are needed on thin gauges, and deposits reach about 400 MPa yield, 600 MPa tensile, 38 % elongation and 175 HB (88 HRB) with service to 760 °C. Silicon leaves glassy slag islands that must be brushed between passes, and the standard carbon level limits post-weld intergranular corrosion resistance — use ER308LSi where low carbon is required. ER308Si has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F). ER308Si has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 195 GPa (28.3 Msi).
What is ER308Si used for?
- Short-circuit GMAW of 304 stainless
- Thin-gauge stainless sheet welding
- Stainless enclosures and cabinets
- Kitchen and food equipment fabrication
- Robotic MIG welding of 304 assemblies
- Tank and hopper seam welds
Advantages
- Readily welded — 95/100, better than 99% of stainless steel grades
Limitations
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
ER308Si properties
Typical room-temperature values for ER308Si-AW; bars are the position among stainless steel grades.
Physical3
ER308Si has a density of 7.95 g/cm³ (0.287 lb/in³), heavier than 81% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
ER308Si has a yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Elongation at break is 38% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
ER308Si is rated for continuous service to 760°C (1,400 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
ER308Si conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of ER308Si takes about 55 MJ of energy and emits 5.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
ER308Si's machinability is fair (40/100, better than 72% of stainless steel grades); weldability excellent (95/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. ER308Si is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ER308Si
Is ER308Si easy to machine?
Weld metal machines much like 304: it work-hardens quickly, so use sharp cutting edges, heavy feed, low speed and ample coolant, and prevent the tool from rubbing or skating on the bead.
Can ER308Si be welded?
For MIG use Ar + 2 % O₂ or Ar + 1–3 % CO₂ (higher CO₂ increases carbon pickup); for TIG use pure argon with an argon back-purge. Hold interpass temperature at 150 °C or below and control ferrite to 5–10 FN to prevent hot cracking.
Can ER308Si be formed, bent or molded?
Forming does not apply to a filler metal. The wire is supplied bright cold-drawn or copper-coated; keep it dry and free of oil during feeding to avoid porosity.
ER308Si chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | ≤ 0.08 | 0.05 |
| Cr | 19.5 – 22 | 20.5 |
| Ni | 9 – 11 | 10 |
| Mn | 1 – 2.5 | 1.8 |
| Sihigh-Si design; improves wetting and flow | 0.65 – 1 | 0.85 |
| Moresidual element | ≤ 0.75 | |
| Cuincluded when copper-coated | ≤ 0.75 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on ER308Si?
Pickle and passivate after welding, or use a stainless-only wire brush, to remove heat tint and the chromium-depleted layer. High-silicon beads polish well, but ferrite bands can appear as streaks after electropolishing.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel ER308Si in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S30880
How much does ER308Si cost?
ER308Si is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ER308Si — frequently asked
What is ER308Si used for?
ER308Si is typically used for short-circuit GMAW of 304 stainless, thin-gauge stainless sheet welding, stainless enclosures and cabinets, kitchen and food equipment fabrication, robotic MIG welding of 304 assemblies and tank and hopper seam welds. In short: best-wetting 308 wire; thin-sheet GMAW filler; silicon slag needs brushing.
What is the yield strength of ER308Si?
ER308Si has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 600 MPa (87 ksi) — stronger than 57% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is ER308Si easy to machine?
Not especially — machinability is rated fair (40/100, better than 72% of stainless steel grades). Weld metal machines much like 304: it work-hardens quickly, so use sharp cutting edges, heavy feed, low speed and ample coolant, and prevent the tool from rubbing or skating on the bead.
Can ER308Si be welded?
Yes — weldability is rated excellent (95/100). For MIG use Ar + 2 % O₂ or Ar + 1–3 % CO₂ (higher CO₂ increases carbon pickup); for TIG use pure argon with an argon back-purge. Hold interpass temperature at 150 °C or below and control ferrite to 5–10 FN to prevent hot cracking.
What surface finishes work on ER308Si?
Pickle and passivate after welding, or use a stainless-only wire brush, to remove heat tint and the chromium-depleted layer. High-silicon beads polish well, but ferrite bands can appear as streaks after electropolishing.
Can ER308Si be formed, bent or molded?
Forming does not apply to a filler metal. The wire is supplied bright cold-drawn or copper-coated; keep it dry and free of oil during feeding to avoid porosity.
What is the maximum service temperature of ER308Si?
ER308Si is rated for continuous use to about 760°C (1,400 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER308Si-AW and ER308Si-SA?
AW is the default condition — choose as the standard supply and qualification state: φ0.8–1.6 mm spooled solid wire for MIG/MAG under Ar+2%O₂ or Ar+CO₂, used as welded at 400 MPa yield and 600 MPa tensile. SA: specify when the whole fabrication is solution treated at 1040–1100 °C and water quenched: δ-ferrite mostly dissolves, yield falls to 260 MPa, elongation rises to 50 % with better intergranular corrosion resistance. Yield strength is 400 MPa in AW versus 260 MPa in SA.
How much does ER308Si cost?
ER308Si is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- AWS A5.9/A5.9M — Bare Stainless Steel Welding Electrodes and Rods — AWS (2017)
- ASME BPVC Section II Part C, SFA-5.9 — ASME (2023)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.