Macroscopic gas inclusion porosity
Macroscopic gas pore porosity occurs when gas bubbles are trapped in the weld during solidification. This leads to visible voids, often caused by inadequate shielding gas or surface contamination.
Physicochemical mechanism of action
Gas bubbles form during welding in the molten pool and cannot be completely avoided. They get trapped if the weld cools too fast or if the shielding gas is insufficient. The bubbles expand during solidification and form visible voids in the metal.
Metallurgical relevance & welding risks
Macro porosity can significantly reduce the mechanical properties of the weld metal. The voids can cause cracks and fractures, especially under load. Porosity can also compromise the integrity of the components.
Shop practice & actionable steps
To avoid macro gas porosity, make sure you have good gas shielding and a clean surface. Use adequate travel speed and watch the cooling rate of the weld. For heavily contaminated materials, do extra cleaning passes.