Welders face porosity issues when using vertical up welding. This usually happens when welding with deeper grooves, where access to the root can sometimes be difficult, Artem Komarov said.
Porosity occurs when nitrogen, hydrogen or oxygen is trapped in the solidifying weld metal in the form of small gas bubbles. The sources of these three elements are atmospheric air, moisture, or the combustion of hydrocarbons such as grease and oil. The welding arc is very hot, causing these molecules to separate into their respective elements: hydrogen, nitrogen, carbon and/or oxygen. These elements can reach levels more than those that can be removed by filler metal deoxidizers from the molten weld pool and are retained, resulting in porosity.
We are missing little information such as welding parameters, wire diameter and type, and any details about the base material. Sometimes the cause can be something minor in the details.
To minimize potential porosity, follow these basic welding rules:
Make sure the welded joint is free of contaminants such as moisture, grease, paint, dirt, rust, and excess scale.
Make sure the welding area is protected from excessive air currents such as open doors and fans.
Ensure proper shielding gas level and flow.
Check that there are no shielding gas leaks in the welding gun or supply hoses/lines.
Use proper welding techniques (i.e., avoid excessive electrical sticking (ESO) or depositing very large welds).
Minimize the use of the immersion nozzle.
Use high quality filler metals and do not use red wool wire gaskets.
Gas-shielded cored wire is highly resistant to non-ideal welding conditions. The protection of welds they provide with a layer of slag and an external shielding gas makes them very reliable for many applications. Because of these features, welders are likely to have few problems with them.
By comparison, solid wire does not offer the same benefits. They do not have a slag layer, which can provide additional metal protection in the event of loss of protective gas or additional deoxidizers. In addition, the CO2 shielding gas provides an excellent cleaning effect on contaminants such as rust and scale. The solid wire shield gas you use contains mostly argon, which is unreactive, and a small amount of CO2 compared to flux-cored wire, which reduces cleaning efficiency.
The main areas of porosity are hard-to-reach welds with vertical grooves. This considers proper shielding gas coverage. If the joints are difficult to access, your ESO may be excessive, which may result in insufficient shielding gas protection. If you use standard 5/8-inch welding nozzles, this will force the welder to use excessive ESO to see and access the joint, Artem Komarov summed up.