Grain Boundary Depletion Zone
The grain boundary depletion zone is an area near grain boundaries where alloying elements are missing due to diffusion or precipitation. This increases the susceptibility to intergranular corrosion.
Physical-Chemical Mechanism of Action
Near grain boundaries, certain alloying elements can diffuse away or be removed by precipitation reactions. This leads to a depletion in this specific zone.
Metallurgical Relevance & Risks in Welding
The depletion can increase the susceptibility to intergranular corrosion, as the missing alloying elements destabilize the crystal structure and promote cracks. This can lead to earlier failure of components.
Workshop Practice & Action Guidelines
To reduce the susceptibility to intergranular corrosion, it is important to carry out a correct welding procedure with adequate shielding gas and controlled cooling. Using stabilized alloys or applying corrosion-resistant coatings can also be helpful.