Porosity brings trouble to any welding method. But it needs extra attention in the case of TIG welds. That is because welders do TIG welding to make the beads pretty. Also, TIG rods have no flux to clean metals and fight porosity.
Contamination is one of the prime causes of porous TIG welds. Only a handful of elements in the process are susceptible to contamination: the rod, the metal, the electrode, and the shield gas. But there are many ways for contamination to occur through the components.
Today, the topic of discussion is the causes of porous TIG welds and how to prevent them. While telling you about the reasons, we will also show you how to avoid them. For that to happen, I recommend you stay tuned till the end.
17 Causes Of Porous TIG Welds
Other than contamination, there are other ways for TIG welds to become porous. We have a list bearing seventeen causes. Thank us later!
- Paints on metals
- Dirt or grease on metals
- Mill scale and rust on steel
- Aluminum oxide
- Gouges or scratches with ground-in contaminants
- Galvanized metals with zinc coating
- Contamination inside pipes
- Absence of sufficient shielding gas
- Excess shielding gas resulting in turbulence
- Drafts or wind
- Contaminated shield gas
- The gas cup causing issues
- Dirt on filler rods
- Contaminated electrode
- Poor torch angles
- The pressure inside pipes makes holes in welds
- Too high amperage makes tungsten blow the rod off
Now, do not get paranoid to see the long list. As we promised, there are ways to get rid of them, and we will discuss each of them in the following section.
Paint is the easiest contaminant for you to remove. If there is any paint on your metal, it has to come off first. Even if it is mostly gone, you have to clean it until the metal starts shining.
How To Prevent It: Clean the surface with acetone or a paint stripper. Take enough thinner and keep removing until the last bit of paint is gone.
Acetone can remove oil traces, but it does not do well with heavy coats. Acetone and paint thinner are flammable. Remember to put them somewhere distant and safe before welding.
2. Dirt Or Grease
If you repair metals instead of fabricating new projects, your metals are probably dirty. That is truer if you work on cars and other machinery. Regardless of that, the grime, grease, and dirt must say goodbye before welding.
How To Prevent It: You can purchase citrus degreasers to remove dirt and grease. Do not forget to wipe out all the degreaser traces. Get some wire brush to handle the thick coats before degreasing.
There is another way. Engine parts tend to absorb oil into crevices and pores in metals. Get a torch to heat the metal gently to sweat out the oil. Afterward, wipe the degreaser down and start heating again. Keep up with the drill until your torch does not bring up grease anymore.
3. Mill Scale And Rust On Steel
Some welding rods bear flux to help burn off mill scale and rust. However, TIG rods do not have them. You have to get rid of them manually before welding.
How To Prevent It: Keep grinding the metals along their joints until they are shiny. You will need an angle or bench grinder based on the part size.
4. Ground-In Contaminants
If your metals have scratches or gouges, they might have contaminants to cause porosity. Using a paint thinner or degreaser to wipe them will not help. Neither will any standard grinder.
How To Prevent It: Grab an angle grinder and use a cut-off disc (a thin one) to clean the scratches. Continue grinding the gouges before they are flawless.
5. Aluminum Oxide
If you have not machined aluminum one or two days before welding, it will develop a thin oxide layer, generating porous welds.
How To Prevent It: You can scrub the aluminum with some stainless steel brush. Buy one or get an old one only used to brush aluminum. The used ones might leave contaminants, which can also ruin welds. Another way is to use chemical agents designed to clean aluminum oxide. You will find them at welding supply shops.
Remember to do the cleaning just before starting your work. If you let the cleaned aluminum rest for too long, the layer will again be back.
6. Insufficient Gas
If there is any shortage of gas to flow through your torch, your welds will develop or corrode holes and pits. However, this problem is easier to fix than it seems.
How To Prevent It: Make sure to turn the gas on at the torch and the tank. Also, see to it that the gas flows. Examine the hose to look for kinks.
Another way is to keep the tank from going empty. The gas will run out at one time. Do not keep welding if it is gone.
The third way is to see the regulator and ensure that the rate of the flow is correct. If needed, read the welder’s manual to adjust it.
7. Galvanized Metal
Galvanized steel has a zinc coating, which requires 420 degrees to melt. Then it will turn to gas at the welding temperature, causing porous welds. What is worse is the toxicity of fumes that will sicken you.
How To Prevent It: Get a grinder to grind the zinc layer of the metals. Put on a mask while you are at it to keep yourself from inhaling the dust or fumes.
8. Tube And Pipe Contamination
If you weld tubes or pipes to carry grease or oil, the contamination may get inside. If the welds are sizzling, the oil may migrate into them and create pores.
How To Prevent It: Use heat and a degreaser to clean the pipe. Wipe both the outside and the inside. Scrub out rigorously so that the oil cannot work into the welds.
9. Excessive Gas
You may use excessive gas, particularly for aluminum. Shield gas with a fast flow causes turbulence and disturbs weld pools, generating ripples or bubbles in the beads.
How To Prevent It: Take the manual and confirm the accuracy of the flow rate. If necessary, adjust your regulator. Or, if you need high flow rates, get a lens for your welding torch. The role of a gas lens is to reduce turbulence and allow for smooth beads even during high gas flows.
10. Drafts And Wind
Shield gas also has issues with drafts and wind. TIG works only with the still air surrounding the welds for smooth gas flows around the arcs and weld beads. Welding in a drafty environment will disrupt the flow and cause weld problems.
How To Prevent It: Have no rooms for wind or drafts. If you must weld outside, assemble a windscreen. Use your body, cardboard, or tarps to block the winds.
If you weld inside, look out for drafts. You will face issues with electric fans. Switch them off. You have to find some other way to manage the heat.
11. Gas Cup Issues
You may also face issues with the gas cup. Before you begin to work, check the condition. Make sure the cup has no cracks. Also, confirm that the cup size is correct for your work.
How To Prevent It: The solution is simple. If the cup is damaged or of the wrong size, buy a new one with the accurate specifications for your project.
12. Contaminated Gas
It usually does not happen, but the contamination sometimes lies in the shield gas. In that case, the problem will either be with the setup or the gas. In both situations, if the hose or the cylinder is moist, the water may react with your weld beads and make bubbles.
How To Prevent It: Make sure the gas setup has no leakage. When the gas flows, small holes will pull air and create problems. Spray the hose and the connections using soapy water. That way, the pinholes will be visible when they make bubbles.
Or, if you think the contamination is in the gas of the cylinder, take it back to the gas supplier, and have it checked.
13. Excessive Amperage
The electrode will overheat if it is very tiny for the used amps or the amps amount is too high. At this, the tungsten might blow off and contaminate your welds. You will understand that this is responsible for the pores when you see the sharp tungsten rod point has become round.
How To Prevent It: Either turn the amps down or change the electrode size by 1/32 inch.
14. Contaminated Electrode
If the electrode has anything except for tungsten, that can dribble the electrode off into the beads. It will cause porosity and pitting to form. So, you must ensure the cleaning and grinding of the electrode are perfect.
If you somehow touch the workpiece, pause at once. You have to grind your electrode to prevent any contamination. Some welders prefer preparing several electrodes beforehand to replace them immediately instead of regrinding the contaminated one.
How To Prevent It: Do not keep working with the electrode you have touched. Stop and grind again. The best option is to prepare backups.
15. Rod Contamination
Rod contamination is rare and happens when they get dirty. It will create the same problems as dirty metals.
How To Prevent It: Simply clean the rod how you clean metal. The easiest method is to use acetone. It is effective when the rods sit loosely around your workshop. Keep them in check because they will get contaminated without your noticing.
16. Torch Angle
TIG torches produce the best result when you hold them straight to the surface. Holding them too flat will keep the shield gas from covering the arcs. Then the welds will oxidize.
How To Prevent It: Fix the angle at 90 degrees. Do not let the torch tip over often, though that will happen when you weld for too long. Try making practice passes with torches before cracking arcs. That will help you see if accidentally leaning causes you to get bad beads.
17. Blowing Bubbles
If you weld sealed pipes or tubes, the air will heat up, raising the pressure. The increased pressure will make the air push through your weld’s end (while it is hot) and create holes in the beads.
How To Prevent It: If air pushes through the welds, preheat the pie’s inside to spread the air. So the heat will not make the air expand further. That means you will then never get much pressure to cause any leaks.
So, we are finally through with the causes of porous TIG welds and how to prevent them. There are so many causes, as you have read. But if you have noticed, the fixes are pretty simple. The one thing it requires you to do in every case is to keep an eye on the equipment and essential accessories. When you do that, you are halfway with prevention.
Cleaning and maintenance are the next topmost important thing here. Plus, try to use the new stuff and have backups ready. That will help you keep up with your work.
That would be all for today. Thanks for reading!