What is Intergranular Penetration in Welding?

Intergranular penetration is the movement of filler metal along the grain boundaries of base metal.

Why is Intergranular penetration happening?

This can happen during welding if the weld pool is not properly protected from oxygen and other atmospheric contaminants. Intergranular penetration can also occur during heat treatment if the metal is not properly cooled.

Intergranular penetration can weaken the metal and make it more susceptible to corrosion. It is important to avoid intergranular penetration when welding or heat treating metals.

How to avoid intergranular penetration?

There are several ways to avoid intergranular penetration:

Welding in a vacuum or inert atmosphere can help protect the weld pool from oxygen and other atmospheric contaminants.
Using low-oxygen welding consumables can also help to prevent intergranular penetration.
Proper cooling of the metal during heat treatment is also important to prevent intergranular penetration.

If intergranular penetration is found in a weld or heat-treated metal, it can be repaired by welding over the affected area with a low-oxygen consumable. In some cases, the metal may need to be heat treated again to repair the intergranular penetration.