Your tungsten keeps melting into the weld pool, and you're not sure why. Maybe it happened two inches into a clean bead, or the tip deformed the second you struck the arc. Either way, TIG tungsten melting usually points to one of three causes: too much amperage, the wrong polarity, or a contaminated electrode.
The good news is that all three are easy to check.
Start with a number. Pure tungsten melts at 3,422°C (6,192°F), so a correctly sized electrode should never go soft during normal welding. If yours does, something in the setup is pushing it past its limit.
That could be a 1/16-inch electrode carrying 150 amps, or a sharp tip running on AC where a ball is expected. Here's the short version before we go deeper.
Quick Answer: Why Your Tungsten Melts (In One Paragraph)
Tungsten melts when amperage exceeds its size rating. Wrong polarity does the same, like AC with a sharp tip. Contaminated electrodes overheat and drip.
Match electrode size to amperage, pick the right tungsten, and the problem disappears. A larger electrode is the quick fix.
If you're brand new to the process, how the TIG process works is worth reading before you start swapping parts. The arc behavior explains why the electrode fails the way it does.
What "Melting" Really Looks Like vs. Normal Wear
Not every deformed tip is a meltdown. On DC with a 2% lanthanated electrode, the tip gradually rounds off after a few inches of welding. The point flattens, the surface stays clean, and the arc stays stable.
That's normal erosion, not melting.
On AC, the tip is supposed to form a small ball. Pure and zirconiated tungsten do this as part of their job. The ball should stay around the same size as the electrode diameter, up to about 1.5 times larger.
Anything bigger has crossed into melting territory.
Here's how to tell them apart:
| Tip Condition | What It Means |
|---|---|
| Slightly flat point on DC | Normal erosion. Re-grind when the point gets fat. |
| Small round ball on AC | Normal balling. Keep it around one electrode diameter. |
| Large sagging ball | Too much amperage or too much AC cleaning action. |
| Mushroomed, rough tip | Current is way above the electrode rating. |
| Split or forked end | Contamination, or DCEP polarity by mistake. |
| Discolored with stuck metal | Touched the puddle or workpiece. Re-grind fully. |
The stuck metal is the biggest clue. Steel melts around 1,370°C to 1,510°C, and aluminum melts at 660°C. Once that metal is on the tungsten, it melts instantly and drags tungsten down into the weld pool.
The First Branch: AC on Aluminum vs. DC on Steel
Before you change anything, look at what you're welding. The fix depends entirely on which mode you're running, AC or DC. These two modes affect the tungsten differently.
If you're welding aluminum, you're on AC. A balled tip is normal, and a sharp point is wrong. You'll know you have a problem only when the ball gets oversized or starts dripping.
If you're welding steel or stainless, you're on DC. The tungsten should stay fairly sharp, with just a slight rounding. Any balling or melting on DC means something is off.
That's the whole decision branch. Everything else follows from this split.
AC and the Ball Shape That's Actually Fine
On AC, the arc polarity flips between electrode-negative and electrode-positive dozens of times per second. The electrode-positive half of the cycle cleans the oxide layer off the aluminum, but it also slams heat into the tungsten tip. That's why the tip balls up.
A healthy AC ball is round, clean, and silver. It should stay around the same size as the electrode, up to 1.5 times larger. When that ball gets oversized, the amperage is too high or the AC balance is set too far toward cleaning.
For aluminum welding techniques, pure and zirconiated tungsten are the go-to choices because they handle this thermal cycle well.
DC and Why a Melted Tip Is a Red Flag
On DC with electrode negative (DCEN), most of the heat goes into the workpiece. That's expected. A properly sized tungsten stays sharp and cool through a long weld.
If the tip melts anyway, one of these three things is happening:
- You're running DCEP by mistake, which puts the heat into the electrode
- Your amperage is far above the rating for that electrode size
- The tip is contaminated, and the contaminant is pulling heat into the electrode
Each of these has a straightforward fix. And for steel welding best practices, DCEN with a sharpened lanthanated or thoriated tip is the standard baseline.
Step-by-Step: Diagnose Your Melted Tungsten
Follow these checks in order. Jumping around can lead you to the wrong fix.
Check Polarity and Machine Settings
Look at the machine first. If you're welding steel, the torch lead should be plugged into the negative terminal, and the work clamp into positive. That's DCEN.
If the torch is in the positive terminal (DCEP), the tungsten will overheat in seconds. The arc will be unstable, and the electrode will melt or split almost immediately.
For aluminum, make sure you're in AC mode. If you've been adjusting the AC balance control, set it back to a standard 65% to 75% electrode-negative. Too much cleaning action means more electrode-positive time, which overheats the tungsten.
Identify Your Tungsten Type and Color Code
The colored band on the tungsten tells you the alloy, and it matters more than most welders admit. The American Welding Society classifies these under the A5.12 specification, and you can verify details on the AWS site.
| Color Code | Tungsten Type | Best Use |
|---|---|---|
| Green | Pure tungsten | AC welding, forms a stable ball |
| Red | 2% Thoriated | DC welding, radioactive grinding dust |
| Gold | 1.5% Lanthanated | AC and DC, solid all-rounder |
| Blue | 2% Lanthanated | AC and DC, most durable all-rounder |
| Grey | 2% Ceriated | DC welding, reliable arc starts |
| Brown | Zirconiated | AC welding, resists ball growth |
If you're running pure tungsten on DC steel, it will melt fast. Pure tungsten doesn't handle DCEN with high current density. Switch to 2% lanthanated, ceriated, or thoriated.
Measure Amperage vs. Electrode Diameter
A 3/32-inch electrode can't carry 250 amps without overheating. That's physics, not opinion.
Manufacturer specifications agree on practical maximums. Here are the numbers most shops use as a baseline:
| Electrode Diameter | Max DC Amps | Max AC Amps |
|---|---|---|
| 1/16" (1.6 mm) | 90 A | 60 A |
| 3/32" (2.4 mm) | 150 A | 100 A |
| 1/8" (3.2 mm) | 250 A | 150 A |
These are safe working limits for lanthanated electrodes at DCEN. Pure tungsten on AC will handle similar values, but with less headroom for sustained high heat.
Inspect the Grind, Ball Size, and Contamination
Now look at the tip itself. A bad grind produces an unstable arc that puts uneven heat into the tungsten. Grind marks should run lengthwise down the taper, away from the arc, never around the tip.
For DC, grind the tungsten to a point with a taper about 2.5 times the electrode diameter. For AC, don't bother with a sharp point. It'll ball up anyway, so a truncated point works fine.
If the tip has contamination, re-grind it completely. Grinding just the discolored part rarely removes all the contaminant, and the next weld will repeat the problem.
How to Fix a Melted Tungsten Tip (Without Changing Everything Else)
Once you've found the cause, the fix takes about five minutes. Work through these steps in order.
Re-grind the entire melted area. Cut or grind away the full melted section. Remove every bit of discoloration and any stuck metal. A clean, fresh taper is the foundation of a stable arc.
Swap to the right tungsten for your current. The fastest fix is often a tungsten swap. For DC steel, use 2% lanthanated or thoriated. For AC aluminum, use pure or zirconiated.
As of 2026, 2% lanthanated is the default recommendation for new welders because it handles both AC and DC without a performance hit.
Set your amperage below the limit. Check the electrode size chart again. If your 1/16-inch tungsten was melting at 150 amps, drop the amperage or move to a 3/32-inch electrode. Checking the chart mid-setup takes ten seconds and saves a lot of grinding.
Verify gas flow and the torch setup. A gas lens provides cleaner coverage and keeps the tungsten protected. The flow rate should sit around 15 to 20 CFH. Too little gas lets air reach the tip and oxidize it.
Too much gas pulls air in through turbulence. Either one causes overheating.
The torch setup also needs a clean collet and a snug back cap. A loose collet adds resistance and heat buildup.
Stop scratch starting. Scratch starts deposit a tiny bit of base metal onto the tungsten every time. That's literal contamination. If your machine has high-frequency start, use it.
If you have lift arc, use that instead.
