TIG welding galvanized steel is not as straightforward as welding regular steel. If you’ve ever tried it, you probably noticed how tricky it can get. The zinc coating burns off, creating toxic fumes and messing with your weld quality. But don’t worry, with the right preparation and settings, you can weld galvanized steel successfully while keeping yourself safe.
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I remember the first time I tried TIG welding galvanized steel—it didn’t go as planned. The welds looked rough, and I had to stop multiple times to clean the area. I learned the tricks to get cleaner welds and reduce the hassle. Now, I want to share everything I’ve learned so you can avoid the same mistakes and get the best results.
If you’re planning to weld galvanized steel with TIG, you need to know about preparation, proper welding settings, safety measures, and the right filler material. Let’s break it all down step by step.
Galvanized Steel and Why It’s Challenging to Weld
Galvanized steel is simply steel coated with zinc to prevent rust. It’s widely used in construction, automotive, and outdoor structures because it holds up well against corrosion. The zinc coating is the biggest challenge when welding.
When you heat galvanized steel, the zinc layer vaporizes, creating a thick white smoke. This isn’t just an inconvenience—it’s toxic. Breathing in zinc fumes can lead to metal fume fever, a short-term illness that causes flu-like symptoms. Beyond the health risks, zinc contamination can cause porous welds, making them weak and brittle.
That’s why proper preparation, ventilation, and protective gear are crucial when TIG welding galvanized steel.
Preparing Galvanized Steel for TIG Welding
Preparation is the key to a successful weld. Unlike mild steel, galvanized steel requires extra work before striking an arc.
Removing the Zinc Coating
The best way to weld galvanized steel is to remove the zinc coating from the weld area. This prevents contamination and reduces fume production. You can remove zinc in several ways:
- Grinding – Use a wire wheel, flap disc, or grinding wheel to clean the metal.
- Chemical Stripping – Apply muriatic acid or vinegar to dissolve the zinc. Make sure to rinse the area well after using chemicals.
- Sandblasting – A fast but more aggressive method for removing coatings.
I personally prefer grinding because it’s quick and gives me better control. The key is to clean at least one inch around the weld joint to avoid contamination.
Cleaning the Metal Surface
After removing the zinc, wipe the metal with acetone or alcohol to remove any oil or dust. TIG welding requires a clean surface, so don’t skip this step.
Choosing the Right Filler Rod
The best filler metal for galvanized steel is ER70S-2 or ER70S-6. These rods work well with mild steel and compensate for slight contamination. If the project requires high strength, you can also use silicon bronze as a brazing filler.
Best TIG Welding Settings for Galvanized Steel
TIG welding galvanized steel requires adjustments in amperage, tungsten selection, and gas flow to ensure a clean weld.
Amperage Settings
The amperage depends on the thickness of the steel. Here’s a quick reference table for setting the correct amperage:
| Steel Thickness | Recommended Amperage |
|---|---|
| 1/16″ (1.6 mm) | 40–70 Amps |
| 1/8″ (3.2 mm) | 80–130 Amps |
| 3/16″ (4.8 mm) | 130–175 Amps |
| 1/4″ (6.4 mm) | 175–225 Amps |
For thin galvanized steel, keeping the amperage on the lower side helps prevent warping and burn-through.
Tungsten Electrode Selection
The best tungsten for TIG welding galvanized steel is 2% thoriated (red) or 2% lanthanated (blue). These types offer better arc stability and control.
Use the appropriate tungsten size based on your amperage range:
| Tungsten Size | Amperage Range |
|---|---|
| 1/16″ | 10–90 Amps |
| 3/32″ | 80–160 Amps |
| 1/8″ | 150–250 Amps |
Always sharpen your tungsten to a fine point before welding for better arc control.
Shielding Gas and Flow Rate
For TIG welding galvanized steel, 100% argon is the best choice. It provides good arc stability and prevents oxidation.
Set your gas flow rate to 15–20 CFH (Cubic Feet per Hour). If you’re welding in a breezy area, slightly increase the flow rate to maintain coverage.
Electrode Polarity
Use DCEN (Direct Current Electrode Negative) for TIG welding galvanized steel. This setting gives better penetration and arc stability.
TIG Welding Galvanized Steel: Step-by-Step Process
Now that you have the right settings, let’s go through the welding process step by step.
Secure and Position the Metal
- Clamp the steel firmly to prevent movement.
- Keep a 1/16″ to 1/8″ gap between the pieces for better penetration.
Start the Arc
- Hold the tungsten 1/8″ away from the metal.
- Use a high-frequency start or scratch start, depending on your welder.
Control Heat Input
- Use a steady travel speed to avoid overheating.
- If the metal gets too hot, let it cool before continuing.
Add Filler Rod Smoothly
- Use the dabbing technique, feeding the filler rod as needed.
- Keep a tight arc length for better puddle control.
Finish the Weld Properly
- Reduce the heat gradually to prevent craters.
- Let the weld cool naturally to avoid cracking.
Safety Precautions When Welding Galvanized Steel
Welding galvanized steel comes with health risks due to zinc fumes. Always follow these safety measures:
- Work in a well-ventilated area – Use a fume extractor or weld outdoors if possible.
- Wear a respirator – A P100-rated mask protects against toxic fumes.
- Use a welding helmet with good visibility – Auto-darkening helmets help maintain arc control.
- Wear protective gloves and clothing – Zinc fumes can irritate the skin.
If you ever start feeling lightheaded or nauseous, stop welding immediately and get some fresh air.
Common Problems and How to Fix Them
Even with the right settings, you might face some challenges. Here’s how to fix them:
- Porosity in the weld – Increase gas flow and make sure the metal is clean.
- Zinc buildup in the weld puddle – Remove more zinc coating before welding.
- Cracking after cooling – Reduce heat input and use proper filler metal.
- Excessive spatter – Lower the amperage and keep a steady travel speed.
Conclusion
TIG welding galvanized steel takes extra effort, but with proper preparation, the right settings, and good technique, you can achieve strong and clean welds. Always remove the zinc coating, use the correct tungsten and filler rod, and prioritize safety when working with galvanized steel.
If you’re new to welding galvanized steel, start with scrap pieces and experiment with different settings. The more you practice, the more confident you’ll become. Once you master it, you’ll have the skills to tackle a variety of galvanized projects with ease.
Frequently Asked Questions
Can you TIG weld galvanized steel without grinding off the zinc?
It’s possible, but not recommended. The zinc coating will contaminate the weld and produce toxic fumes.
What happens if you breathe in zinc fumes?
You may develop metal fume fever, which causes flu-like symptoms such as nausea, chills, and headaches.
What is the best filler rod for TIG welding galvanized steel?
ER70S-2 or ER70S-6 are the best choices for strong and clean welds.
Why do my TIG welds look rough on galvanized steel?
This usually happens due to zinc contamination or incorrect settings. Make sure to grind off the zinc before welding.
