TIG welding is an excellent method for joining metal, and it can make beautiful welds. However, if you aren’t careful, you can get pinholes in the bead from TIG welding.
How to stop pinholes when TIG welding? The best way to prevent pinholes when TIG welding is to avoid some of the common causes of them, such as:
- Shielding gas isn’t shielding the bead
- Some part of the weld is contaminated
- The amperage is set too high
- The welding arc is too long
- You are pushing the bead too fast
- Current is cut off too quickly at the end of the weld
Any of these problems are easy to solve if you know what to look for.
The high temperatures in TIG welding can cause the weld to oxidize in air. The torch supplies shield gas that protects the weld from oxygen while it’s extremely hot. If the gas isn’t distributed correctly, this can cause pinholes and cracks. What disrupts the shield gas?
The gas isn’t on.
We’ve all done this at one time or another. If the gas isn’t on, you will get a lot more spark and spatter from the arc. Make sure the gas is turned on when you start welding.
Torch at the wrong angle.
The torch should be held vertically to get gas flowing directly on the arc and the weld. If you lean the torch over too far, the shield gas won’t cover the arc, and the weld is unshielded. This leads to pitting and cracking in the joint. The effect is the same as not using gas at all.
Poor gas flow.
Not enough gas is coming out to cover the arc and the weld, leading to pinholes and spatter. Adjust the gas flow as directed by the manufacturer. If the flow is set correctly, make sure the tanks aren’t empty.
Problems with gas delivery.
If the gas is on, the tank is full, and the flow is adjusted correctly, check the hose for kinks or leaks that reduce the flow from the nozzle. Make sure all the connections are tight, and gas isn’t leaking anywhere. A spray of soapy water on the connections can help you find leaks.
Too much gas
If the gas is flowing too fast, that’s also a problem because it creates turbulence. If the gas flow is too fast, the current can disrupt the weld puddle and cause pinholes or cracks. It is like the wind whipping up waves on a lake. This is mainly a problem with aluminum.
Gas is contaminated with moisture.
If the gas bottles aren’t handled properly, moisture can mix with the shielding gas. This is rare, but it does happen from time to time. Make sure the gas company has purged the bottles correctly and filled them with welding-grade gas.
Drafts or wind
Fast-moving air can disrupt the flow of shielding gas and cause oxidation. TIG welding is best done inside. If you have to work outside, make sure to have adequate protection from the wind. Do whatever you have to do to shield your torch from the wind-use tarps, cardboard, or anything else you can to block the wind so that you can weld without disturbance.
Getting a good weld requires all the metal to be clean and free of contaminants. Paint, oil, grease, and rust can all cause pinholes to form in the weld bead. This is particularly important in TIG welding. The electrode and rods used for TIG welding don’t have any flux to clean a weld or handle impurities. You must get everything clean before you crack an arc.
Clean the work piece
Ideally, you should be welding clean, shiny metal. Use acetone or paint thinner to remove paint. Use a degreaser to remove oil and grease. Wipe the metal down with a clean rag after using the cleaners to remove all traces of solvent, too.
Pro tip: Make sure you put solvents away before welding! You don’t want flammable materials anywhere near a torch running at 6,000 degrees.
Use a Grinder
Rust and corrosion also inhibit good welds. If the surface is rusty, grind the workpiece with a bench or angle grinder to knock off the rust and get a good surface. Keep grinding until the metal gleams.
If the surface has any cracks or gouges, they need special attention. Cracks usually hold grease and grime. If you are repairing a metal surface that has cracking, make sure to get a grinder wheel into the cracks to clean out any impurities hiding at the bottom of the crack.
Deal with oxidation on aluminum
A thin layer of aluminum oxide coats the surface of the aluminum. This layer will interfere with your weld and can cause pinholes and pits. Scrub the oxide layer off with a stainless steel wire brush, or use a chemical cleaner to strip off the oxide surface.
Once the aluminum is clean, weld it quickly. Don’t let the aluminum sit more than a day after removing the oxide layer, or the air will cause the oxide layer to re-form. If that happens, you have to clean it all over again.
Clean the electrode
Electrodes can become contaminated with weld spatter, especially if you are welding dirty metal. Clean the electrode and remove spatter, so you have a pure tungsten tip.
Re-grind / re-shape the electrode
TIG welding requires proper shape for the electrode tip. Some welds work better with a point, while others need a rounded tip. Excessive heat can distort the end of the electrode and cause problems with the weld. Re-shape your electrode as needed to get the best weld possible.
Use clean, dry filler rod
Make sure your rod is clean and dry. Store the rods in a closed container and keep them away from contaminants. If your metal is clean, but you are still having problems, try cleaning your rod with acetone or a degreaser, just to make sure.
It is possible to TIG weld using just about any small metal rod as a filler. It is best to use a filler rod of known quality that matches the metal you are welding. If weld quality is essential, don’t try to weld with things like stripped wires or leftover bits of metal rod.
Be careful with high-carbon steel
The carbon in high-carbon steel like hot-rolled material, springs, and tool steel acts as a contaminant in the weld. The rods for some welding processes contain flux to help clean the weld, but TIG rods don’t. You have to choose rods carefully for TIG welding high-carbon steel.
The best filler rod to use for TIG welding high-carbon steel is AWS ER70-S2. This rod is formulated to make clean welds in high-carbon steel despite impurities in the base metal itself.
Too Much Current
Welding with the amperage set too high produces excess heat. The extra heat can cause faults in the weld bead, including pinholes. Consult the manual for your welder for the proper settings for your metal. Adjust welder as directed for the best bead quality.
Arc Too Long
Holding the electrode too far from the weld puddle causes the bead to heat up, which can lead to problems with the bead. Hold the electrode closer to the workpiece. The ideal distance from the electrode to the weld puddle is the thickness of the electrode. For most TIG welding, that is 1/16 of an inch….about the thickness of a dime. Keep the electrode close to the bead for a clean weld.
Moving Too Fast
If you move too quickly, gaps and pinholes can appear in the bead. Keep a steady rhythm of moving the electrode, pushing the rod into the puddle, and pulling the rod back. Don’t rush if you want a pretty bead with no holes or cracks.
If you cut off the arc too quickly at the end of the weld, pinholes will form. Instead of cutting off the arc quickly, use the pedal or hand control to taper the arc slowly. Some welders have a built-in feature that tapers the arc for you. Reducing the arc slowly lets the bead cool at the correct pace to leave a smooth end with no pinholes.