Porosity in Welding - Causes and Corrective Actions

Porosity is one of the common problems faced by the welders when they weld using the arc welding process, right? Here in this article, we will discuss the various type of causes of porosity and how to avoid porosity during the welding procedure and the best part is we also have in video form, check it out. So, first, let us learn what is porosity?

Porosity is a small hole or pores present in the weld bead. These holes can happen either over or under the weld surface and randomly are of different sizes.

Weld Holes

There are various reasons for the formation of pores on the weld surface. Reasons like:

• Contaminated electrode, consumable, filler wire, work surface, etc.
• Air or kind of draft disturbs the delivery of the shielded gas which results in porosity. Fan 25 feet away also can disrupt the delivery of shielded gas.
• Size of the arc also plays an important role; longer arc increases the chances of porosity.
• Defected gun nozzle, distance of nozzle from welding material, or the wrong angle of the gun can also help in forming the pores. So, always check the nozzles before you start welding.
• Presence of rust, paint, oil, chemicals, etc. releases a large volume of gas. As this decompose gas starts forming, and oxidation starts which leads to moisture and lastly gives us the nice big holes.
• Inappropriate quantity of flux. To avoid this always use the branded electrodes.
• Improper welding procedure and incorrect welding surface treatment.
• Weld surface that contains high Sulphur, Phosphorous or Silicon may result in highly gaseous composition which results in holes during the welding process.

Luckily, porosity is the defect which has 90% prevention rate, let's check out the corrective actions to take to prevent the porosity:

• The electrode or filler wire should be cleaned and made free from oil, grease, chemical, moisture, etc., not only the electrode but the base metal also should be free from moisture, oil, grease or any other toxins.
• Before welding, the oxidation process must be done without any mistakes to remove all the content of oxygen from base metal. The oxidation process will prevent contact with oxygen while the welding process. A proper deoxidant electrode should be used.
• Weld metal should not be exposed in air, which will prevent the metal from contact with oxygen or hydrogen. If the metal gets moisture by someway easy fix is to preheat the surface at the temperature between 94-degree Celcius to 104-degree Celcius.
• To avoid the weld defects the electrode, weld metal, flux or filler wire must be ensured to be free from moisture and in dry condition.
• Proper arc length and flow of current should be maintained.
• Gun nozzle should be checked before the welding procedure, the gap between the nozzle and the welding surface should not be more which results in contact with air and creates the moisture and then the porosity, again the less gap between them will overheat the welding surface.
• A 5- to 15-degree angle which is perpendicular to the joint, is an acceptable angle for forehand or backhand methods with GMAW or FCAW guns and SMAW electrodes.
• Chemical composition of the surface should be predicted prior, so the defect can be avoided. There are so many types of electrodes available in the market for different types of weld surfaces. If you are new to the welding world, take suggestions from the experienced welders or contact us, we are here happy to help. To get more information on every single type of electrode, visit this site.

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 Also, check our another article on How to weld Cast Iron and what is Phosphor Bronze.