Harris 308 stainless steel MIG GMAW welding alloy is an ER308L classified low-carbon austenitic stainless steel MIG wire per AWS A5.9/A5.9M. Harris Products Group, a Lincoln Electric company, manufactures 308L stainless MIG wire to serve a broad range of 304, 304L, 308, and 308L stainless steel welding applications. Available in multiple diameters and spool sizes, WeldingMart stocks Harris 308L stainless MIG wire as an authorized Harris distributor. This page covers the full Harris 308 stainless steel MIG GMAW welding alloy product line.
ER308L is the most widely used stainless steel MIG wire, suitable for over 60% of all stainless steel welding applications. The "L" designation means low carbon (0.03% max C), which prevents sensitization — the intergranular corrosion attack that occurs when chromium carbides precipitate at grain boundaries during welding heat cycles. By specifying ER308L, engineers ensure the weld zone resists carbide precipitation and maintains corrosion resistance in as-welded condition without post-weld heat treatment in most service environments.
| Specification | Value |
|---|---|
| AWS Classification | ER308L (AWS A5.9/A5.9M) |
| Vendor | Harris Products Group (Lincoln Electric Company) |
| Available Diameters | 0.025, 0.030, 0.035, 0.045, 1/16 in |
| Cr content | 19.5–22.0% |
| Ni content | 9.0–11.0% |
| C content (max) | 0.03% |
| Mn content | 1.0–2.5% |
| Si content | 0.65–1.0% (Si for ER308LSi) |
| Tensile Strength (as-welded) | ≥ 80,000 psi (550 MPa) |
| Elongation | ≥ 35% |
| Ferrite Number | 4–12 FN (prevents solidification cracking) |
| Polarity | DCEP |
| Shielding Gas | 98% Ar / 2% O₂ or 98% Ar / 2% CO₂ |
AWS A5.9 and its metric equivalent A5.9M govern stainless steel bare electrodes and rods for arc welding. Published by the American Welding Society. Harris technical data at harriswelding.com.
- Type 304 and 304L stainless steel: ER308L is the standard filler for welding 304 and 304L — the most common austenitic stainless steels used in food processing, chemical, and general industrial service.
- Food service and dairy equipment: Welding 304/304L tanks, piping, valves, and fittings where FDA-acceptable welds and intergranular corrosion resistance are required.
- Chemical processing vessels: Fabricating stainless MIG welding wire vessels and piping handling non-chloride acids, alkalis, and organic solvents at ambient and elevated temperatures.
- Architectural and ornamental stainless: Welding decorative 304 stainless railings, panels, and structural elements where weld zone appearance and corrosion resistance are both important.
- Pharmaceutical equipment: FDA-regulated process equipment and clean-in-place (CIP) piping systems requiring ultra-clean MIG weld quality.
- General fabrication: Any 304/304L stainless steel structure, bracket, tank, or assembly requiring corrosion-resistant MIG welds without post-weld annealing.
| Parameter | ER308L Stainless MIG (0.035 in typical) |
|---|---|
| Shielding Gas | 98% Ar / 2% O₂ or 98% Ar / 2% CO₂ (tri-mix for spray) |
| Flow Rate | 35–50 CFH |
| Polarity | DCEP |
| Wire Feed Speed (0.035 in) | 200–350 IPM |
| Voltage | 18–24 V (short-circuit); 24–30 V (spray) |
| Current (0.035 in) | 100–200 A |
| Transfer Mode | Short-circuit (thin gauge); spray or pulsed (thick sections) |
| Back Purge | 100% Ar back purge required for root pass in piping |
| Preheat | Not required for standard austenitic stainless at ambient |
| Interpass Temp | ≤ 350 °F (to prevent sensitization) |
Stainless steel has lower thermal conductivity than carbon steel — heat accumulates in the joint and can sensitize the heat-affected zone if interpass temperature exceeds 350 °F. Allow stringer beads to cool adequately. Use 100% argon back purge on the root pass of pipe and tubing to prevent sugar (granular oxidation) on the backside of the joint.
Store in a dry location at 40–120 °F. Stainless steel wire should be kept separate from carbon steel tools, brushes, and storage to prevent iron contamination that causes rust-staining of stainless welds. Use stainless-steel-dedicated wire brushes and grinding discs on stainless fabrications. Keep original spool packaging sealed until use; rewrap unused wire in clean plastic.
Harris 308L MIG wire is compatible with any constant-voltage GMAW power source. Pulse-capable machines (Lincoln Power Wave, Lincoln Power MIG 256) enable pulsed spray transfer, which significantly reduces heat input and improves weld quality on thin stainless sheet. Use 98% Ar / 2% O₂ for short-circuit and spray transfer (most common); tri-mix (90 He / 7.5 Ar / 2.5 CO₂) for high-production spray. See also Harris 4130 Chrome-Moly MIG Wire and all welding wire.
- What is ER308L stainless MIG wire used for?
- ER308L is the primary filler for welding Type 304 and 304L austenitic stainless steel — the most commonly used stainless alloys. The "L" (low carbon) designation prevents intergranular corrosion (sensitization) in the weld zone without requiring post-weld heat treatment, making ER308L suitable for food service, chemical, pharmaceutical, and architectural applications.
- What is the difference between ER308L and ER308LSi?
- ER308LSi contains 0.65–1.0% silicon vs 0.30–0.65% Si in ER308L. The higher silicon in ER308LSi improves fluidity, wettability, and appearance of the weld pool — particularly in short-circuit transfer mode. This makes ER308LSi the preferred choice for out-of-position welding and thin stainless sheet. ER308L and ER308LSi are otherwise equivalent for most corrosion resistance and mechanical property purposes.
- What shielding gas should I use for stainless MIG welding?
- The standard is 98% Ar / 2% O₂ or 98% Ar / 2% CO₂. The small addition of O₂ or CO₂ stabilizes the arc and improves weld pool fluidity. Avoid high-CO₂ blends (C25) — excessive carbon pickup from CO₂ can increase weld metal carbon content, risking sensitization in multi-pass welds. For automated spray transfer, 90 He / 7.5 Ar / 2.5 CO₂ tri-mix is common for high deposition rates.
- What does carbide precipitation mean for stainless steel welding?
- During welding, chromium in stainless steel reacts with carbon at grain boundaries in the 800–1,600 °F temperature range (the sensitization zone). The result is chromium carbide precipitation, which depletes chromium from the grain boundaries and makes the weld zone susceptible to intergranular corrosion — a failure mode known as "weld decay." Using low-carbon ER308L (≤ 0.03% C) minimizes this risk, as less carbon is available to form carbides.
- Do I need back purge when MIG welding stainless steel pipe?
- Yes, for the root pass (first inside pass on a pipe joint). Without argon back purge, the inside of the weld oxidizes severely — producing "sugaring" (granular oxidation) that significantly weakens the joint, reduces corrosion resistance, and creates crevices for bacteria growth in food and pharmaceutical applications. Use 100% argon back purge at low flow (5–15 CFH) to displace oxygen from inside the pipe before tacking.
- Can I use ER308L wire to weld 316L stainless steel?
- ER308L is not recommended for welding 316L stainless. Type 316L contains 2–3% molybdenum for improved pitting resistance in chloride environments — ER308L does not contain molybdenum and would deposit a non-matching, lower corrosion resistance weld metal. Use ER316L for 316L stainless applications in marine, chloride-bearing, and food/pharma environments.
- What ferrite number should stainless MIG wire deposits have?
- ER308L deposits typically show 4–12 FN (Ferrite Number). A minimum of 3–5 FN is important for preventing solidification hot cracking (Schaeffler diagram analysis shows fully austenitic welds are crack-susceptible). Above 15–20 FN, ferrite content can reduce notch toughness at cryogenic temperatures. 4–12 FN is the safe operating range for most 308L MIG applications.
Selecting the right ER308L wire diameter and grade for your stainless MIG welding application depends on the base metal thickness, transfer mode, and position requirements. The wire diameter range — 0.025 in for thin sheet, 0.030–0.035 in for general fabrication, 0.045 in for production — determines heat input per pass and deposition rate. ER308L is the standard for Type 304/304L and prevents carbide precipitation by limiting carbon to 0.03% maximum. ER308LSi is preferred when weld pool fluidity and out-of-position wettability are more important than exact chemistry match. The intergranular corrosion risk (sensitization) from welding with standard 308 rather than 308L is most critical in services involving nitric acid, ammonium, and dilute sulfuric acid. The ferrite number in ER308L deposits (4–12 FN) helps prevent solidification cracking and makes this a more robust filler than fully austenitic alternatives. For the wire diameter and shielding gas combination, 0.035 in with 98 Ar / 2 O₂ is the most widely used setup for structural stainless fabrication.
Welding 308 stainless steel with ER308L MIG wire demands attention to heat management, joint fit-up, and post-weld finishing more than carbon steel work. The corrosion resistance of Type 304 and 304L stainless steel depends on a minimum 10.5% chromium content at the surface — grinding with contaminated abrasives, poor interpass temperature control, or inadequate back purge on pipe all compromise this. Use stainless steel wire brushes and grinding wheels dedicated to stainless; never use a wheel previously used on carbon steel. The iron particles embedded in a contaminated wheel transfer to the stainless surface and create rust spots within days.
For the root pass on stainless pipe, set back purge flow at 5–15 CFH using 100% argon. Check the inside of the pipe after the first pass: clean root welds appear bright silver-gold. Any blue, brown, or granular appearance ("sugaring") indicates oxygen contamination and requires rework. For structural applications on plate and sheet, back purge is not mandatory but reduces heat-affected zone sensitization in multi-pass joints.
Short-circuit transfer on 0.035 in ER308L is ideal for sheet metal (14–16 gauge) and out-of-position work. Set voltage to 18–21 V with wire feed speed at 200–280 IPM. Stringer beads are preferred over weave beads — weaving increases heat input per inch of weld and elevates HAZ sensitization risk. On 1/4 in and thicker material, spray transfer or pulsed MIG provides better fusion and deposition rates; set voltage to 26–29 V.
Interpass temperature must be monitored on multi-pass welds. Allow each pass to cool below 350 °F before depositing the next pass. Excessive interpass temperature creates a wide sensitization band in the HAZ that defeats the purpose of using low-carbon ER308L. A contact thermometer or temperature-indicating sticks at the tack locations are the simplest monitoring tools.
| Problem | Cause | Fix |
|---|---|---|
| Porosity in weld | Contamination on base metal or wire; inadequate shielding gas coverage | Clean base metal with acetone; increase gas flow to 30–35 CFH; check for drafts |
| Sugaring on backside (pipe) | Insufficient or absent back purge | Increase Ar back purge; purge for 30 seconds before tacking |
| Intergranular corrosion after service | Excessive interpass temp; using ER308 instead of ER308L | Monitor interpass temp ≤ 350 °F; confirm ER308L (not ER308) specification |
| Weld pool too fluid (burn-through on thin sheet) | Voltage too high for gauge; spray transfer on thin material | Reduce voltage 1–2 V; switch to short-circuit mode; reduce wire feed speed |
| Lack of fusion | Travel speed too fast; voltage too low | Slow travel speed; increase voltage 1 V; use stringer beads for better fusion |
The 308 family of stainless MIG wires includes several variants serving different purposes:
- ER308L: Standard low-carbon filler for Type 304/304L stainless. Maximum 0.03% carbon prevents sensitization. Best choice for structural fabrication, food service, pharmaceutical, and architectural stainless welding.
- ER308LSi: Higher silicon (0.65–1.0%) version of ER308L. Improved arc stability, weld pool fluidity, and out-of-position performance. Preferred for thin sheet, MIG welding in short-circuit transfer, and appearance-critical applications.
- ER309L: Used for welding dissimilar metals — joining stainless steel to carbon steel, or as a butter layer. Higher alloy content prevents dilution from carbon steel from reducing corrosion resistance below acceptable levels.
- ER316L: Contains 2–3% Mo for superior pitting resistance in chloride (marine, chemical processing) environments. Use for Type 316/316L stainless applications.
Harris 308 stainless steel MIG welding alloy is available in multiple spool weights and wire diameters to match production volume. For thin sheet applications (0.025 in diameter), OEM panel fabrication, and pharmaceutical tubing, check Harris's full ER308L range. For austenitic stainless structural work, 0.035 in wire in the 30 lb spool is the most economical format.
Welding 308 stainless steel with ER308L MIG wire demands attention to heat management, joint fit-up, and post-weld finishing more than carbon steel work. The corrosion resistance of Type 304 and 304L stainless steel depends on a minimum 10.5% chromium content at the surface — grinding with contaminated abrasives, poor interpass temperature control, or inadequate back purge on pipe all compromise this. Use stainless steel wire brushes and grinding wheels dedicated to stainless; never use a wheel previously used on carbon steel. The iron particles embedded in a contaminated wheel transfer to the stainless surface and create rust spots within days.
For the root pass on stainless pipe, set back purge flow at 5–15 CFH using 100% argon. Check the inside of the pipe after the first pass: clean root welds appear bright silver-gold. Any blue, brown, or granular appearance ("sugaring") indicates oxygen contamination and requires rework. For structural applications on plate and sheet, back purge is not mandatory but reduces heat-affected zone sensitization in multi-pass joints.
Short-circuit transfer on 0.035 in ER308L is ideal for sheet metal (14–16 gauge) and out-of-position work. Set voltage to 18–21 V with wire feed speed at 200–280 IPM. Stringer beads are preferred over weave beads — weaving increases heat input per inch of weld and elevates HAZ sensitization risk. On 1/4 in and thicker material, spray transfer or pulsed MIG provides better fusion and deposition rates; set voltage to 26–29 V.
Interpass temperature must be monitored on multi-pass welds. Allow each pass to cool below 350 °F before depositing the next pass. Excessive interpass temperature creates a wide sensitization band in the HAZ that defeats the purpose of using low-carbon ER308L. A contact thermometer or temperature-indicating sticks at the tack locations are the simplest monitoring tools.
| Problem | Cause | Fix |
|---|---|---|
| Porosity in weld | Contamination on base metal or wire; inadequate shielding gas coverage | Clean base metal with acetone; increase gas flow to 30–35 CFH; check for drafts |
| Sugaring on backside (pipe) | Insufficient or absent back purge | Increase Ar back purge; purge for 30 seconds before tacking |
| Intergranular corrosion after service | Excessive interpass temp; using ER308 instead of ER308L | Monitor interpass temp ≤ 350 °F; confirm ER308L (not ER308) specification |
| Weld pool too fluid (burn-through on thin sheet) | Voltage too high for gauge; spray transfer on thin material | Reduce voltage 1–2 V; switch to short-circuit mode; reduce wire feed speed |
| Lack of fusion | Travel speed too fast; voltage too low | Slow travel speed; increase voltage 1 V; use stringer beads for better fusion |
The 308 family of stainless MIG wires includes several variants serving different purposes:
- ER308L: Standard low-carbon filler for Type 304/304L stainless. Maximum 0.03% carbon prevents sensitization. Best choice for structural fabrication, food service, pharmaceutical, and architectural stainless welding.
- ER308LSi: Higher silicon (0.65–1.0%) version of ER308L. Improved arc stability, weld pool fluidity, and out-of-position performance. Preferred for thin sheet, MIG welding in short-circuit transfer, and appearance-critical applications.
- ER309L: Used for welding dissimilar metals — joining stainless steel to carbon steel, or as a butter layer. Higher alloy content prevents dilution from carbon steel from reducing corrosion resistance below acceptable levels.
- ER316L: Contains 2–3% Mo for superior pitting resistance in chloride (marine, chemical processing) environments. Use for Type 316/316L stainless applications.
Harris 308 stainless steel MIG welding alloy is available in multiple spool weights and wire diameters to match production volume. For thin sheet applications (0.025 in diameter), OEM panel fabrication, and pharmaceutical tubing, check Harris's full ER308L range. For austenitic stainless structural work, 0.035 in wire in the 30 lb spool is the most economical format.