Lincoln Electric UltraCore 316L FCAW-G 0.045-inch welding wire (AWS A5.22 classification E316LT1-1/4) is a gas-shielded flux-cored wire engineered specifically for welding 316 and 316L austenitic stainless steel. The "L" designation denotes extra-low carbon content (0.03% maximum), which reduces sensitization — the carbide precipitation at grain boundaries that makes stainless steel susceptible to intergranular corrosion in service environments involving temperatures between 800 °F and 1,650 °F (427–899 °C). The 2–3% molybdenum addition to the alloy provides enhanced resistance to pitting and crevice corrosion in chloride-containing environments, distinguishing 316L weld metal from standard 304/308L deposits.
UltraCore 316L is formulated with stabilized chemistry — nitrogen, titanium, and niobium additions that control the weld metal microstructure to produce a smooth, polished bead appearance and minimal post-weld cleanup. The titanium and niobium stabilizers also ensure the wire qualifies as E316LT1-1 (100% CO₂) and E316LT1-4 (Ar/CO₂ mix) classifications in a single product, offering flexibility in shielding gas selection without stocking two wire lots.
- AWS Classification: E316LT1-1/4 per AWS A5.22/A5.22M
- Carbon: 0.03% max (low-carbon designation)
- Chromium: 17.0–20.0%
- Nickel: 11.0–14.0%
- Molybdenum: 2.0–3.0%
- Manganese: 0.5–2.5%
- Silicon: 0.5–1.5%
- Diameter: 0.045 in (1.14 mm)
- Tensile Strength (as-welded): ≥80,000 psi (550 MPa)
- Yield Strength (0.2% offset): ≥57,000 psi (393 MPa)
- Elongation: ≥25%
- Charpy Impact (–4 °F / –20 °C): ≥20 ft-lbf (27 J)
- Ferrite Number (FN): 3–15 FN typical (controlled for crack resistance)
- Preheat / Interpass Temperature: 300 °F (149 °C) maximum interpass to control ferrite
Lincoln UltraCore 316L is purpose-built for corrosion-critical stainless steel fabrication in demanding service environments:
- Chemical and Petrochemical Processing: Reactor vessels, heat exchangers, piping, and pressure vessels handling chloride-bearing fluids, acids, and corrosive process streams where 304L's lack of molybdenum is insufficient.
- Marine and Offshore Structures: Seawater piping, pump housings, valve bodies, and subsea hardware where chloride pitting resistance is a code requirement.
- Pharmaceutical and Sanitary Manufacturing: Tanks and lines that must pass passivation and electro-polishing specifications. Low carbon content minimizes sensitization that could harbor bacteria in crevice-corrosion pits.
- Food Processing Equipment: Washdown tables, hoppers, and conveyors where daily sanitizing cycles with chlorine-based cleaners demand molybdenum-bearing stainless.
- Pulp and Paper Mills: Digester components, bleach plant piping, and black-liquor evaporator tubes where highly acidic, chloride-laden environments require 316L metallurgy.
- Power Generation: Boiler headers, steam lines, and condenser tubing fabrication and repair where elevated-temperature corrosion service is combined with thermal cycling.
Lincoln UltraCore 316L is designed for all-position welding with external shielding gas. Follow these parameters for optimum results:
- Primary recommendation: 75–85% Argon / 20–25% CO₂ (C25 or equivalent). Argon-rich blends produce lower spatter, smoother bead contour, and better side-wall fusion on vertical-up passes compared to 100% CO₂.
- Alternate: 100% CO₂ (qualifies as T1-1 designation). Spatter increases slightly and bead profile flattens, but penetration profile improves — suitable for production flat/horizontal work where spatter cleanup cost is managed.
- Flow rate: 35–50 CFH. Increase toward 50 CFH in drafty environments. Do not use nitrogen or mixed nitrogen blends — nitrogen absorbs into austenitic stainless weld metal and can cause porosity.
- Flat/Horizontal (1F, 2F, 1G, 2G): 27–30 V / WFS 280–350 ipm
- Vertical-Up (3G, 3F): 24–26 V / WFS 200–250 ipm. Use a triangular or Z-weave pattern; do not allow the puddle to become convex or undercut will develop at the toes.
- Overhead (4G, 4F): 24–26 V / WFS 190–230 ipm. Use short stringer passes — weaving in the overhead position causes excessive heat input and potential burn-through on light gauge material.
- CTWD (Contact-Tip-to-Work Distance): 3/4 in to 1-1/4 in (19–32 mm). Longer CTWD increases electrical resistance heating of the wire extension, improves deposition rate, but reduces penetration. Stay within this range.
For stainless steel FCAW-G, use a slight drag angle (5–15° toward direction of travel) to maintain shielding gas coverage over the solidifying puddle. Avoid push angles greater than 5° — they can trap slag. On multi-pass welds, allow each pass to cool to 300 °F maximum interpass temperature before depositing the next bead; this is critical for maintaining corrosion resistance (over-heating causes chromium carbide precipitation that depletes the heat-affected zone's corrosion protection). Remove slag between passes with a stainless-wire brush dedicated to stainless work only — never use a brush that has been used on carbon steel, as iron contamination on the brush will embed ferrous particles in the 316L weld surface, creating rust staining.
- Store in original sealed packaging in a dry area at 50–100 °F (10–38 °C). UltraCore 316L wire is packaged in moisture-barrier bags with desiccant to maintain wire quality in humid climates.
- Once opened, store partially used spools in a sealed plastic bag with fresh desiccant and return to storage. Do not leave wire exposed in the feeder overnight in humid shop environments.
- Rusty or oxidized wire should be discarded. Surface rust or discoloration on stainless FCAW wire is evidence of moisture exposure and will cause porosity, inconsistent arc behavior, and out-of-specification weld chemistry.
- Wire conditioner: For wire spools that have been stored for extended periods, run 6–12 inches of wire through the conduit before beginning production welding to purge any conduit-lubricant buildup from the wire surface.
UltraCore 316L is compatible with any CV (constant voltage) MIG/FCAW power source capable of maintaining stable voltage in the 24–30 V range at the deposition rates listed above. Recommended Lincoln Electric platforms include:
- Lincoln Power Wave S350 and S500 (advanced waveform control for smooth FCAW)
- Lincoln Invertec V350-Pro
- Lincoln Power MIG 256 and 350MP
- Lincoln Idealarc CV-400 and DC-400 (legacy platforms still in service)
Primary base metals (direct classification match):
- AISI 316 and 316L austenitic stainless steel (all product forms)
- ASTM A240 Grade 316/316L plate
- ASTM A312 Grade TP316L pipe
- ASTM A276 Grade 316L bar and shapes
Secondary base metals (dissimilar or similar-chemistry):
- 321 stainless (titanium-stabilized, where 316L deposit is acceptable per engineering)
- 317L stainless (higher Mo; 316L filler accepted for repair
- Carbon steel to 316L overlays (buffer layer required; see Lincoln procedure D1.6)
Q1: What is the difference between 308L and 316L stainless welding wire?
A: ER308L / E308LT1 is designed for welding 304 and 304L base metals and contains no molybdenum. E316LT1-1/4 (UltraCore 316L) adds 2–3% molybdenum, which significantly improves pitting and crevice corrosion resistance in chloride environments. Use 308L for general 304 stainless fabrication; use 316L for marine, chemical, or food-processing applications where chloride exposure is present.
Q2: Can UltraCore 316L be used on 304L stainless steel?
A: Yes — 316L filler metal is an acceptable overmatch for 304 and 304L base metals in terms of corrosion resistance and mechanical properties. The resulting deposit will have better corrosion performance than strictly required, but the joint will meet or exceed the 304L base metal specification. Many contractors standardize on 316L wire to avoid mixing wire lots when both 304 and 316 are in the shop.
Q3: What causes porosity in stainless steel FCAW-G welds?
A: The most common causes are: (1) wind or drafts disrupting shielding gas coverage — shield the work area; (2) shielding gas flow too low — maintain 35–50 CFH; (3) moisture-contaminated wire or flux — replace wire and check storage conditions; (4) nitrogen-containing gas mixtures — use Ar/CO₂ only; (5) excessive CTWD — stay within 3/4–1-1/4 in.
Q4: What is the maximum interpass temperature for 316L stainless welding?
A: 300 °F (149 °C). Exceeding this temperature on multi-pass welds causes chromium carbide precipitation in the heat-affected zone (sensitization), which depletes the chromium available for corrosion protection. Use a contact pyrometer or temperature-indicating crayons to check interpass temperature on the parent metal adjacent to the weld joint before depositing each subsequent pass.
Q5: Does UltraCore 316L wire require a preheat?
A: Austenitic stainless steel does not require preheat for hydrogen control (unlike carbon steel) and is generally welded at ambient temperature. However, on very thick section (over 1-1/2 in) in cold shop environments (below 40 °F), a mild warm-up to 100–150 °F reduces the risk of thermal shock cracking and improves fusion on the root pass. Never preheat 316L to the temperatures used for carbon steel (300–500 °F) — excess heat increases sensitization risk.
Q6: How do I prevent rust staining on my 316L FCAW welds?
A: Rust staining on 316L welds is almost always caused by iron contamination from carbon steel grinding wheels, wire brushes, fixtures, or tooling. Use only stainless-steel dedicated wire brushes, stainless-steel grinding wheels, and clean fixtures that have not contacted carbon steel. After welding, passivate with citric acid (preferred) or nitric acid per ASTM A380 to restore the passive film if the project specification requires it.
Q7: What ferrite number should 316L FCAW welds have?
A: AWS D1.6 and most pressure-vessel codes require 3–15 FN for austenitic stainless weld deposits. This ferrite range provides sufficient hot-crack resistance without compromising corrosion properties. UltraCore 316L is formulated to consistently deposit within this range. Ferrite can be measured non-destructively with a Fischer Feritscope or equivalent instrument.