What Is Welding Porosity?

Welding porosity is a defect that affects the integrity of welded metal components in a wide variety of industries. It appears as tiny pockets of air or gas trapped between metal pieces, which can lead to weak spots and potential failure. It is estimated that 2-5% of all welds are subject to porosity, resulting in loss of tens of billions of dollars a year in scrapped parts, repairs and legal liabilities.

In this article, we’ll explore what welding porosity is, how it occurs, and the best methods to prevent and detect it. So read on to learn more about what welding porosity is, and how to prevent it.

What is welding porosity?

Welding porosity is an issue that any welder will have to deal with in their line of work. It is an unwanted phenomenon that is often encountered while welding between two separate pieces of metal.

Put simply, it is air pockets or voids that form between the two pieces of metal being joined together, usually as a result of solidification. These air pockets can weaken the weld and compromise its integrity, making it more prone to failure.

Causes of welding porosity

Porosity often occurs as a result of the welding process itself and the materials used while welding. Poor gas shielding, incorrect wire feed speed, and incorrect voltage settings can all cause porosity to form in the weld zone.

Additionally, carbon and sulfur levels in the materials being welded, as well as the presence of oil contaminants and other corrosion-causing substances, can affect the weld area and lead to porosity. The joint design and misalignment of the materials being welded can also increase the chance of voids forming.

Preventing and repairing welding porosity

Preventing porosity is possible through understanding the causes and taking measures to prevent them before the weld.

Adequate shielding gas and maintaining the correct voltage settings is important as well as ensuring that the joint and materials being joined are aligned correctly. Cleaning the surfaces being welded of any metal oxide and contaminants can also help reduce the possibility of porosity forming.

Repairing a weld with porosity requires a filler material to be applied to voids to fill the area and unify the weld again. Depending on the sizes of the voids, the filler material can be gas metal arc welding (GMAW), flux-cored arc welding (FCAW), tungsten inert gas (TIG), or plasma arc welding (PAW).


Welding porosity is an unwanted problem that many welders face.

Though it cannot always be prevented, understanding its causes and taking the necessary measures to minimize them can help improve the quality of the welds. Repairing porosity also requires the use of filler materials, like GMAW, FCAW, TIG, or PAW, in conjunction with the welding technique used for the two pieces of metal being joined. Citation URLs: https://www. millerwelds. com/resources/articles/understanding-welding-porosity https://www. lincolnelectric. com/en-us/support/welding-how-to/Pages/how-to-prevent-and-repair-porosity-in-welds. aspx

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