What causes porosity in TIG welding?
Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal. Leaks in the gas line, too high a gas flow rate, draughts and excessive turbulence in the weld pool are frequent causes of porosity.
How can welding porosity be prevented?
7 Ways to Eliminate Porosity in Your Welds
- Check your gas flow rate.
- Make sure you gas flow rate is not see too high.
- Check for gas leaks.
- Keep an adequate contact-tip-to-work distance (CTTWD).
- Avoid drafty conditions.
- Clean the surface to be welded.
- Watch your travel angle.
How do you fix porosity?
The best approach is to remove all of the material that has any trace of porosity. I sometimes do this with an abrasive cut-off disc, making a tiny slice in the weld, which removes the porous area.
How can crater porosity or cracks be prevented?
Finally, to prevent crater cracks – cracking that occurs if you stop welding prior to completing a pass on a weld joint – use a backfill technique to provide greater thickness to the crater. This technique entails backing up slightly to fill in the area at the end of the weld prior to extinguishing the arc.
What causes porosity in a TIG weld?
Common causes of porosity are due to contamination and moisture. Sometimes a user can use too much shielding gas that can affect the quality of the weld. Zinc coating or galvanized metal used in passivating the weld can also be a cause of porosity in TIG welding.
How can I prevent porosity in my welding area?
The first step to preventing porosity is controlling the flow of air within your shop or project area. Drafty shop or project area conditions will, unfortunately, provide a steady supply of air to the weld zone. This can be the result of an open door, wind, and weather conditions or air being emitted from machinery.
Why do TIG welds have to be spotlessly clean?
Unlike other types of welding, TIG doesn’t use any flux that can protect the weld from contaminated metal. That means all the metal has to be spotlessly clean before you crack an arc. If the metal isn’t shiny, you won’t get a good weld.
What does porosity in a welding bead mean?
Porosity in welding refers to the unfortunate release of shielded gas that’s been trapped inside the weld bead. Consequently, it leaves rounded holes outside the weld area and can also take the form of elongated holes which are known as wormholes that refers to a large amount of gas being trapped inside the weld metal.