Understanding TIG Filler Rod Selection
TIG welding filler rods (also called filler wire or welding rods) are added to the weld pool to build up the joint and provide the desired mechanical and chemical properties. Unlike MIG welding where filler is automatically fed, TIG welding requires the welder to manually add filler rod. Selecting the right filler rod is essential for weld quality, strength, and service performance.
The filler rod must be compatible with the base metal, suitable for the intended service conditions, and appropriate for the welding position and technique. Using the wrong filler rod can result in weak welds, cracking, corrosion, or other failures.
Carbon Steel Filler Rods
ER70S-2
ER70S-2 is the most commonly used TIG filler rod for carbon steel. The "S" indicates solid wire, and the "2" indicates the deoxidizer level (titanium, zirconium, and aluminum).
Characteristics:
- 70,000 psi minimum tensile strength
- Excellent for rimmed and semi-killed steels
- Triple deoxidized for rust and scale tolerance
- Smooth, stable arc
ER70S-6
ER70S-6 contains higher manganese and silicon for better wetting and bead appearance. It's preferred for multi-pass welds and applications where bead appearance is important.
Stainless Steel Filler Rods
ER308L
ER308L is the most common stainless steel filler, used for welding 304 and 304L stainless steels. The "L" designation indicates low carbon, essential for preventing sensitization.
ER309L
ER309L is used for joining stainless steel to carbon steel or for overlaying carbon steel with stainless. Its higher alloy content accommodates dilution from carbon steel.
ER316L
ER316L matches 316 and 316L stainless steels, providing improved corrosion resistance with 2-3% molybdenum for pitting resistance.
Aluminum Filler Rods
ER4043
ER4043 is the most widely used aluminum filler, containing 5% silicon. It's good for most aluminum grades and less prone to cracking than 5356.
ER5356
ER5356 contains 5% magnesium and is stronger than 4043. It's better for 5xxx series aluminum and applications requiring anodizing.
Nickel Alloy Filler Rods
Nickel alloy fillers like ERNiCr-3 (Inconel 82) and ERNiCrMo-3 (Inconel 625) are used for Inconel 600, nickel alloy fabrication, and dissimilar metal joints.
Titanium Filler Rods
ERTi-2 matches grade 2 commercially pure titanium, while ERTi-5 matches Ti-6Al-4V alloy. Both require excellent shielding for quality welds.
Filler Rod Diameters
Common TIG filler rod diameters: 0.020" for very thin materials, 0.030" for thin materials, 1/16" for general fabrication, 3/32" for medium thickness, 1/8" for thick materials.
Storage and Handling
Store in clean, dry conditions, keep original packaging until use, protect from contamination, and handle with clean gloves. Don't use rods that have become dirty or oxidized.
Conclusion
TIG filler rod selection directly affects weld quality and performance. Keep a selection of common filler rods: ER70S-2 for steel, ER308L for stainless, ER4043 for aluminum.
