TIG welding is one of the most precise and versatile welding processes, and one of the key factors in achieving strong, high-quality welds is selecting the right filler rod. When I first started TIG welding, I didn’t realize just how important the filler metal was. I thought any rod that “worked” would be fine, but I quickly learned that using the wrong one can lead to weak welds, cracking, or even contamination.
If you’re working with stainless steel, aluminum, carbon steel, or exotic metals, the right filler rod makes all the difference. It affects everything from weld strength to corrosion resistance and even the appearance of the final bead.
I’ve spent years experimenting with different rods for different metals, and today, I’ll walk you through the key factors in selecting the right TIG welding filler rod.
If you’re new to TIG welding or just looking for a clear reference, this guide will help you choose the best filler rod for your next project.
TIG Welding Filler Rods
TIG welding filler rods are metal wires used to fill gaps and create strong, lasting welds. They come in different materials, diameters, and compositions, depending on the base metal you are welding.
Each filler rod has a specific classification number, which indicates its composition and intended use. For example, an ER70S-2 rod is a common choice for mild steel welding, while ER4043 is used for aluminum.
To choose the right filler rod, you need to consider:
- The type of base metal you’re welding
- The strength and properties you need in the final weld
- The weld appearance and finishing requirements
- The welding position and conditions
Now, let’s go through the most common types of TIG welding filler rods and their applications.
TIG Welding Filler Rod Selection Chart
This chart provides a quick reference for selecting the right TIG filler rod based on the base metal you’re working with.
| Base Metal | Recommended Filler Rod | Features & Best Use |
|---|---|---|
| Mild Steel | ER70S-2, ER70S-6 | Good ductility, smooth bead, minimal spatter |
| Stainless Steel | ER308L, ER309L, ER316L | Corrosion-resistant, high strength |
| Aluminum | ER4043, ER5356 | ER4043 for ease, ER5356 for strength |
| Copper & Bronze | ERCuSi-A, ERCuAl-A2 | Great for electrical conductivity, corrosion resistance |
| Titanium | ERTi-1, ERTi-2, ERTi-5 | High strength, corrosion-resistant |
| Nickel Alloys | ERNiCrMo-3, ERNiCu-7 | Heat and corrosion-resistant |
Now, let’s go deeper into each type and when to use them.
Mild Steel TIG Welding Filler Rods
Mild steel is one of the most commonly welded metals, and it requires a filler rod that matches its properties.
- ER70S-2 – This is my go-to filler rod for mild steel. It contains deoxidizers like titanium and zirconium, making it great for welding over rust, mill scale, or slightly contaminated surfaces. It produces a smooth, clean weld with good strength.
- ER70S-6 – If I need a little more penetration and a slightly better bead appearance, ER70S-6 is a solid choice. It has higher silicon content, which helps the weld puddle flow smoothly.
Both are excellent choices, but if you’re working on dirty or slightly rusted steel, ER70S-2 is more forgiving.
Stainless Steel TIG Welding Filler Rods
Stainless steel welding requires a filler rod that maintains its corrosion resistance and strength. Choosing the right rod depends on the type of stainless steel you’re welding.
- ER308L – This is the most commonly used rod for welding 304 stainless steel. It provides excellent corrosion resistance and is easy to work with.
- ER309L – If you’re welding stainless steel to mild steel, this is the rod you want. It works well as a dissimilar metal filler and helps prevent cracking.
- ER316L – For marine applications and high-corrosion environments, ER316L is ideal because it contains molybdenum, which adds extra corrosion resistance.
If you’re unsure, ER308L is the safest bet for most stainless steel welding projects.
Aluminum TIG Welding Filler Rods
Aluminum welding can be tricky, and the filler rod you choose makes a big difference in weld strength and appearance.
- ER4043 – This is the most common aluminum filler rod. It’s easy to work with, has great flow, and is less prone to cracking. I use this for general-purpose aluminum welding.
- ER5356 – If you need higher strength and better corrosion resistance, ER5356 is the way to go. It’s great for marine applications and structural aluminum.
If you’re welding cast aluminum, ER4043 is usually the better choice because it handles impurities well.
Copper and Bronze TIG Welding Filler Rods
For copper and bronze, you need a filler rod that matches their unique properties.
- ERCuSi-A (Silicon Bronze) – This is one of my favorites for TIG brazing copper, bronze, and even steel. It has excellent corrosion resistance and produces a smooth, golden-colored weld.
- ERCuAl-A2 (Aluminum Bronze) – If you’re welding aluminum bronze alloys, this rod offers high strength and excellent wear resistance.
These rods are commonly used in artistic metalwork, electrical applications, and marine welding.
Titanium TIG Welding Filler Rods
Titanium is a specialized material, often used in aerospace, medical, and racing applications. It requires precise heat control and shielding gas protection.
- ERTi-1 and ERTi-2 – These are commercially pure titanium rods used for lightweight and corrosion-resistant welds.
- ERTi-5 – This is a stronger, heat-resistant alloy used in aircraft and motorsports applications.
Titanium welding isn’t for beginners, but if you need strength with low weight, it’s an amazing material to work with.
Nickel Alloy TIG Welding Filler Rods
Nickel alloys are used for high-temperature, high-corrosion environments, like chemical plants and aerospace applications.
- ERNiCrMo-3 – This is a common filler rod for welding Inconel and other nickel-chromium-molybdenum alloys.
- ERNiCu-7 – If you’re welding Monel alloys, this is the right filler rod for the job.
Nickel alloys require precise heat control and clean welding conditions to avoid contamination.
Conclusion
Selecting the right TIG welding filler rod is essential for strong, clean, and durable welds. Whether you’re working with mild steel, stainless steel, aluminum, copper, titanium, or nickel alloys, there’s a filler rod designed for your needs.
If you’re just getting started, ER70S-2 for mild steel, ER308L for stainless steel, and ER4043 for aluminum are safe choices for most applications. Always consider strength, corrosion resistance, and weldability when making your selection.
Over time, you’ll get a feel for which rods work best for different projects. Practice on scrap metal, experiment with different rods, and always clean your base metal properly before welding.
FAQs
What is the best filler rod for mild steel?
ER70S-2 is great for general use, especially if the metal isn’t perfectly clean. ER70S-6 flows better but works best on clean steel.
Can I use the same filler rod for stainless steel and mild steel?
Yes, ER309L is designed for welding stainless steel to mild steel.
Which aluminum filler rod is stronger, ER4043 or ER5356?
ER5356 is stronger, but ER4043 is easier to work with and has better crack resistance.
What is the best filler rod for TIG brazing?
Silicon bronze (ERCuSi-A) is an excellent choice for TIG brazing steel, copper, and brass.
Do I need different shielding gas for different filler rods?
Most TIG welding uses pure argon, but some exotic materials may require helium or a mixed gas blend.
Endow Russel the owner chief editor of giftendow.com . I am a mechanical engineer and assign to an local firm with much experience in welding and industrial equipment.
