TIG welding problems and how to fix them
Every welder knows it: the weld is porous, the arc is unstable or the seam turns black. The cause is usually easy to find if you know where to look. Below are the most common TIG welding problems, with the likely cause and what to do about it.
Pores or holes in the weld
Cause: dirt on the material or the filler rod (grease, oil, paint, oxide, moisture), too little gas, a draught or a leaking hose.
Fix:
- Clean the material and the filler rod with acetone or a degreaser.
- Check that the hose and connections are tight and that the gas cylinder is not almost empty.
- Welding outdoors or in a draught? Shield the spot and use a gas lens, which makes the gas flow calmer.
The weld turns black or grey
Cause: the weld is not protected well enough from oxygen. This happens with too little gas, too little post-flow, too large a distance to the workpiece or a poor cup.
Fix:
- Set a longer post-flow, so the weld and the electrode cool under gas.
- Keep the torch close to the workpiece and use a cup that is wide enough.
- On stainless and titanium it also helps to protect the back side. Read how to get good gas coverage.
The arc is unstable or wanders
Cause: a contaminated or badly ground electrode, too long an arc or a poor contact of the work clamp.
Fix:
- Grind the electrode again, along its length. Read how to grind it properly.
- Keep the arc short, about as long as the diameter of the electrode.
- Clean the spot where the work clamp sits down to bright metal and check the clamp.
The electrode gets contaminated or melts
Cause: you touched the weld pool or the filler rod with the electrode, the current is too high or there is no gas.
Fix:
- Break off the contaminated tip and grind a new one.
- Choose an electrode that suits your current, and use the right polarity: DC minus for steel and stainless.
- Make sure gas is already flowing before you start the arc.
Poor penetration or the weld sits on top
Cause: too little current, moving too fast or too long an arc.
Fix: raise the current a little, slow down and keep the arc shorter. On thicker material it helps to bevel the edge.
Burn-through or distortion
Cause: too much current or staying too long in one spot. Thin material and stainless heat up quickly.
Fix: lower the current, weld in short steps and let the material cool in between. Use clamps or a copper backing bar to draw heat away.
Parts that help
Many problems get smaller with good cups, a gas lens and a clean electrode. Not sure which parts fit your torch? Use our selection guide or send us a message via the contact page.
Want to go over the basics again? Read our complete guide to TIG welding.