Harris 308 Stainless Steel TIG GTAW Welding Rod (.035 in, 36 in, 10 lb Box — 0308TF0) is a bare wire filler metal classified under AWS A5.9 as ER308. It is formulated to weld 304 and 304L austenitic stainless steel base metals — the most widely used stainless steel in industrial, food processing, and chemical applications. ER308 deposits weld metal with a nominal composition of 20% chromium and 10% nickel, closely matching the chemistry of 304 stainless base metal, which ensures that the weld joint's corrosion resistance and mechanical properties closely track those of the parent material.
The .035 in (0.9 mm) diameter is a small-diameter TIG rod designed for precision work on light-gauge stainless sheet (16 ga–3/16 in), root passes on stainless pipe, and instrumentation tubing. The fine diameter melts at lower amperage settings, giving the welder precise puddle control without burning through or causing excessive heat input into the heat-affected zone. Harris Products Group — a Lincoln Electric company — manufactures ER308 rod to tight compositional limits that consistently produce the 4–12 FN (Ferrite Number) range required to resist hot cracking in multi-pass stainless TIG welds.
- AWS Classification: ER308 per AWS A5.9/A5.9M
- Carbon: 0.08% max
- Chromium: 19.5–22.0%
- Nickel: 9.0–11.0%
- Manganese: 1.0–2.5%
- Silicon: 0.30–0.65%
- Phosphorus: 0.03% max
- Sulfur: 0.03% max
- Diameter (this SKU): .035 in (0.9 mm)
- Rod length: 36 in (914 mm)
- Package: 10 lb box
- Tensile Strength (as-welded): ≥85,000 psi (586 MPa)
- Yield Strength (0.2% offset): ≥55,000 psi (379 MPa)
- Elongation: ≥35%
- Ferrite Number: 4–12 FN typical (controls hot cracking resistance)
Harris ER308 .035 in TIG rod is the standard choice for general-purpose stainless steel TIG welding across a wide range of industries:
- Food and Beverage Processing Equipment: Tanks, piping manifolds, hoppers, conveyors, and washdown tables fabricated from 304 or 304L stainless sheet and plate. ER308 TIG welds are smooth, slag-free, and easily passivated to meet FDA 3-A sanitary standards.
- Pharmaceutical and Biotech: Bioreactor vessels, clean-room piping, and filter housings in 304L stainless where full-penetration TIG root passes are required for sanitary weld quality inspection under ASME BPE (Bioprocessing Equipment) standards.
- Chemical Process Piping: Small-diameter 304 SS instrumentation tubing and process lines where the .035 in rod is ideal for root passes and fill passes with controlled heat input on wall thicknesses below 0.120 in.
- Architectural Stainless Steel: Handrails, column covers, sculptures, and decorative panels in 304 stainless where a bright, uniform bead finish is visible in the final installation and aesthetic quality is as important as structural integrity.
- Commercial Kitchen Equipment: Sinks, countertops, range hoods, and food-contact surfaces requiring durable, corrosion-resistant TIG welds that can be polished to a #4 or #8 mirror finish without weld bead inconsistency.
- HVAC and Refrigeration Stainless Piping: Refrigerant-carrying 304 stainless tubing systems where TIG's clean, flux-free process is preferred over MIG to avoid flux residue in the refrigerant circuit.
- Process: GTAW (TIG), DCEN (DC Electrode Negative)
- Tungsten: 2% ceriated (grey) or 2% lanthanated (gold/black) — grind to a sharp taper for DCEN stainless work. Do not use pure tungsten (AC) for steel TIG.
-
Amperage by base metal thickness:
- 16 ga (0.060 in): 40–65 A
- 14 ga (0.075 in): 55–80 A
- 12 ga (0.105 in): 70–100 A
- 11 ga (0.120 in): 80–115 A
- 3/16 in: 100–150 A
- CTWD (tungsten to work): 3/16–5/16 in (5–8 mm) for fine work with .035 in rod. Keep arc length short to minimize heat input and prevent the arc from wandering.
- Primary: 100% Argon at 12–20 CFH. Argon is standard for stainless TIG and produces bright, clean beads with minimal oxidation tint on the bead and adjacent HAZ.
- Helium blends: 25–75% He / balance Ar for thicker sections requiring increased travel speed. Helium raises heat input without increasing current, enabling faster travel on 3/16 in and thicker material.
- Back-purging: On full-penetration root passes in pipe and tubing, back-purge with 100% Argon at 2–5 CFH. Failure to back-purge on stainless causes oxidized "sugar" on the root ID, which is a crevice-corrosion initiation site and a defect requiring excavation and repair.
The .035 in rod diameter requires consistent, light feeding into the leading edge of the puddle. Over-feeding a small-diameter rod causes the rod to ball up, contaminate the tungsten, and produce an irregular bead profile. Maintain a constant rod feed angle of 15–20° and a torch work angle of 75–80°. On thin stainless sheet (16–14 ga), use a backing bar (copper or stainless) to absorb heat and prevent distortion. Watch the heat-tint color behind the weld — a straw or light golden color indicates well-controlled heat input; dark blue or gray-black indicates excess heat or inadequate gas coverage and impending corrosion issues.
- Store in original sealed box in a clean, dry environment. Stainless TIG rod picks up surface oxides in humid conditions, leading to bead discoloration and increased arc instability.
- Handle rods with clean gloves or a clean cloth only — skin oils on .035 in rod are proportionally more significant relative to the rod's small cross-section and will cause contamination streaks visible in the final weld bead.
- Keep rod dedicated to stainless work. Do not contaminate ER308 rod with carbon steel surfaces, tooling, or fixtures — iron particles on stainless filler metal embed in the weld and create rust spots that violate corrosion specifications.
- Inspect rods for surface tarnish or discoloration before use. Bright, silver-white surface indicates proper storage. Yellowing or bronzing indicates surface oxidation — rods in this condition should not be used for critical stainless welds.
Harris ER308 .035 in TIG rod is compatible with any DC TIG welding machine. Recommended Lincoln Electric platforms:
- Lincoln Precision TIG 225 and 275 (DCEN mode)
- Lincoln Square Wave TIG 200 (DCEN mode for stainless)
- Lincoln Dynasty 200 DX and 280 DX (precision DCEN for thin stainless)
- Lincoln PTA-17 and PTA-17V TIG torches with Pyrex gas lens cups
Primary base metals:
- AISI 304 and 304L austenitic stainless steel (all product forms)
- ASTM A240 Type 304/304L plate and sheet
- ASTM A312 Type TP304/304L pipe
- ASTM A276 Type 304 bar and shapes
Secondary base metals:
- 301 stainless (lower Cr/Ni; ER308 provides adequate corrosion resistance)
- 302 stainless (ER308 is the standard filler per AWS A5.9 selection table)
- 308 and 308L stainless (direct composition match)
- CF-8 and CF-8M stainless castings (302/304 equivalent cast grades)
Q1: What is the difference between ER308 and ER308L TIG rod?
A: ER308 has up to 0.08% carbon; ER308L has a maximum of 0.03% carbon. The lower carbon in ER308L reduces sensitization (chromium carbide precipitation at grain boundaries) during welding and in service at elevated temperatures between 800–1,650 °F. For most room-temperature applications, ER308 is acceptable. For welding 304L base metal, for applications involving frequent high-temperature cycles, or when post-weld sensitization is a corrosion concern, use ER308L. Harris offers both grades.
Q2: Can I use ER308 to weld 316 stainless steel?
A: ER308 can be used on 316 stainless in applications where the additional corrosion resistance of molybdenum is not required by the engineering specification. However, the ER308 deposit will not contain molybdenum and will have lower pitting resistance than a 316L deposit in chloride environments. For full corrosion matching on 316 and 316L base metals, use ER316L rod.
Q3: Why does my stainless TIG weld turn blue or gold color?
A: Oxidation tint (heat discoloration) on the weld bead or adjacent HAZ is caused by chromium oxide forming at elevated temperature in the presence of atmospheric oxygen. Light straw/gold is minor surface oxidation. Dark blue or black indicates severe oxidation and a significant loss of corrosion resistance in the HAZ. Causes: insufficient shielding gas flow, gas coverage disrupted by drafts, gas hose leaks, or post-weld oxidation before the metal cools below 800 °F. Always post-flow the gas for 8–12 seconds after extinguishing the arc on stainless TIG.
Q4: How do I prevent sensitization in 304 stainless TIG welds?
A: Sensitization occurs when chromium carbides precipitate at grain boundaries during slow cooling through the 800–1,650 °F range. To minimize it: (1) use ER308L rather than ER308 filler; (2) maintain low heat input — keep interpass temperature below 300–350 °F; (3) use narrow stringer passes rather than wide weaves; (4) ensure post-weld solution anneal if the application is corrosion-critical. The .035 in small-diameter rod helps control heat input by limiting the maximum amperage practical for the rod size.
Q5: What is Ferrite Number (FN) and why does it matter for stainless TIG welds?
A: Ferrite Number is a measure of the magnetic delta ferrite phase in an austenitic stainless weld deposit. AWS D1.6 and most stainless WPS specifications require 3–15 FN. Below 3 FN, the weld is susceptible to hot cracking during solidification. Above 15 FN, corrosion resistance and ductility may be compromised. Harris ER308 is formulated to deposit within the 4–12 FN range, providing a safety margin against both hot cracking and over-ferritization.
Q6: Do I need to back-purge when TIG welding 304 stainless pipe with ER308?
A: For full-penetration butt welds in 304 stainless pipe, back-purging is strongly recommended to prevent oxidation of the root ID (the "sugar" condition). A back-purge of 100% Argon at 2–5 CFH, maintained from tack welding through the entire root pass plus sufficient time for the root to cool below 600 °F, will produce a bright, oxide-free root bead. Many food-grade, pharmaceutical, and chemical piping specifications mandate back-purging and root bead visual inspection as a hold point before fill and cap passes.
Q7: What's the best way to get a mirror-polish finish on a 308 TIG weld?
A: For polishable cosmetic stainless welds: (1) use a tight, consistent bead with no undercut or overlap — the .035 in rod at controlled amperage produces a smooth, low-profile bead; (2) remove oxidation tint with a dedicated stainless wire brush immediately after welding; (3) grind with progressively finer grit stainless-dedicated grinding discs (80→120→180 grit); (4) blend with Scotch-Brite or non-woven abrasive belts (240→320 grit); (5) finish with a flap wheel or buffing compound to #4 or #8 mirror finish. Never use abrasives that have contacted carbon steel.