The Ultimate Guide to TIG Welding Filler Rods – Types, Uses, and Selection Tips
TIG welding filler rods are the backbone of producing strong, clean, and precise welds. Whether you’re a beginner just learning the basics or an experienced welder perfecting high-spec jobs, understanding the different types of filler rod for TIG welding is essential. In this guide, we’ll break down filler rod materials, classifications, sizes, applications, and selection tips so you can make the right choice for every project.
For top performance, pair your filler rod with precision welding tools from WCR Tools — including welding magnets and magnetic welding grounds.
What is a TIG Welding Filler Rod?
In Tungsten Inert Gas (TIG) welding, the filler rod is a separate consumable used to add material to the weld joint. Unlike MIG welding (where the wire feeds automatically), TIG welding requires the welder to manually feed the rod into the weld pool while controlling the torch with the other hand.
The filler rod must be compatible with the base metal to ensure:
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Proper fusion
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Strong weld integrity
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Resistance to cracking or corrosion
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Desired mechanical properties
Key Factors in Choosing the Right Filler Rod
When selecting a TIG filler rod, consider:
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Base Metal Composition – Match rod alloy to your material (e.g., stainless to stainless).
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Joint Design – Some rods flow better for thin sheet metal, others are better for thick sections.
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Required Properties – Strength, corrosion resistance, ductility, and color match.
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Welding Position – Certain rods handle overhead or vertical welds better.
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Shielding Gas – Some alloys work best with pure argon, others may require argon-helium blends.
Types of TIG Welding Filler Rods by Material
1. Mild Steel Filler Rods
Common for general fabrication, automotive repair, and structural work.
Popular Grades:
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ER70S-2 – Contains deoxidizers for welding over light rust, scale, or contaminants.
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ER70S-6 – Higher silicon and manganese for smoother bead appearance and strong mechanical properties.
Best for: Mild steel frames, sheet metal repair, pipe welding.
For easier joint alignment before welding, use WCR Tools Welding Magnets to hold your workpieces securely in place.
This engine mount that I fabricated was made of 1018 mild steel that was TIG welded with a ER70s-6 Filler rod
2. Stainless Steel Filler Rods
Designed for corrosion resistance and high strength.
Popular Grades:
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ER308L – For 304 stainless steels.
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ER309L – For joining dissimilar metals (e.g., stainless to carbon steel).
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ER316L – For 316 stainless, excellent for marine and chemical environments.
Best for: Food-grade equipment, chemical tanks, marine repairs.
Properly matching a filler rod to its base material is critical to a good TIG weld. Here is a 304 stainless steel flange run with a 3/32" 308L filler rod.
3. Aluminum Filler Rods
Lightweight and corrosion-resistant, but requires precision.
Popular Grades:
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ER4043 – Excellent flow, good for general aluminum fabrication.
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ER5356 – Stronger than 4043, better for anodizing and marine environments.
Best for: Aluminum trailers, automotive components, boats, bike frames.
4. Nickel and High-Nickel Alloy Filler Rods
Used in extreme heat or corrosive environments.
Popular Grades:
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ERNiCr-3 – For Inconel and high-temperature applications.
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ERNiCu-7 – For Monel and seawater service.
Best for: Aerospace, power generation, offshore oil rigs.
5. Copper and Copper-Alloy Filler Rods
Excellent thermal and electrical conductivity.
Popular Grades:
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ERCu – For pure copper repairs.
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ERCuSi-A (Silicon Bronze) – Great for joining dissimilar metals and TIG brazing.
Best for: Electrical bus bars, bronze art, and ornamental work.
6. Titanium Filler Rods
Ultra-light, high-strength, and corrosion-resistant. Requires strict gas coverage.
Popular Grades:
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ERTi-2 – Commercially pure titanium.
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ERTi-5 (Ti-6Al-4V) – High-strength aerospace grade.
Best for: Aerospace, motorsports, medical implants.
TIG Filler Rod Size Selection
Filler rods are available in diameters typically ranging from 1/16” (1.6mm) to 1/8” (3.2mm).
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Thin material – Use thinner rod for easier control and lower heat input.
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Thick material – Use thicker rod to deposit more metal quickly.
Common sizes and uses:
| Diameter | Best For |
|---|---|
| 1/16” (1.6mm) | Sheet metal, thin tubing |
| 3/32” (2.4mm) | General fabrication |
| 1/8” (3.2mm) | Heavy plate, thick joints |
Storage and Handling of TIG Filler Rods
Moisture, dirt, or oil can contaminate rods and weaken welds.
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Store in sealed containers or rod tubes.
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Wipe with acetone before use.
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Keep aluminum rods away from steel particles to prevent contamination.
Storage tubes like these are a great way to not only keep your filler rod clean and organized, but they are helpful in mobile welding situations as well.
Expert Tips for Using TIG Filler Rods
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Feed Consistently: Maintain a steady rhythm to avoid cold laps and uneven beads.
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Match Filler to Base Metal: Avoid cracking and poor fusion.
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Adjust Amperage for Alloy: Aluminum often needs higher amps than steel.
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Use Proper Shielding Gas: Most filler rods use pure argon; exotic metals may need mixes.
Why Filler Rod Choice Matters for Weld Quality
The right filler rod ensures:
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Weld strength meets or exceeds base material.
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Corrosion resistance matches application needs.
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Appearance blends with surrounding material.
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Code compliance for critical industries.
Choosing the wrong filler can lead to cracks, porosity, premature corrosion, or weld failure — all costly mistakes.
Final Thoughts
From ER70S-6 mild steel filler rods to ERTi-5 titanium alloys, each type of TIG welding filler rod is engineered for a specific purpose. By understanding the properties, applications, and best practices for each, you can take your TIG welding projects from average to professional-grade.
For maximum results, use quality welding accessories from WCR Tools — including the ArcLight Spanner Regulator Wrench, Magnetic Welding Ground with Burn Bar, and Heavy-Duty Welding Magnets to make setup faster, safer, and more precise.
FAQ
Q1: What type of filler rod is best for TIG welding mild steel?
For mild steel, ER70S-2 or ER70S-6 filler rods are most common. ER70S-2 is great for welding over light contaminants, while ER70S-6 offers higher silicon for smoother beads.
Q2: Can you use the same filler rod for MIG and TIG welding?
Yes, many filler alloys like ER70S-6 are used in both MIG and TIG welding, but TIG rods are typically cut to length and have no copper coating like MIG wire.
Q3: What size TIG welding filler rod should I use?
For thin materials, use 1/16” (1.6mm) filler rod; for general fabrication, use 3/32” (2.4mm); and for heavy plate, use 1/8” (3.2mm).
Q4: Do TIG filler rods expire?
Filler rods do not expire, but they can become contaminated by moisture, oil, or dirt. Store them in a clean, dry container to maintain quality.
Q5: What filler rod should I use for welding aluminum?
ER4043 is the most common aluminum filler rod for general use, while ER5356 offers higher strength and is better for anodizing or marine environments.