Intercrystalline Segregation
Intergranular segregation is the enrichment of foreign atoms at interfaces between crystallites during solidification. This increases susceptibility to hot cracking and corrosion.
Physical-chemical mechanism of action
During cooling of molten materials, foreign atoms (such as oxygen, nitrogen, or hydrogen) can concentrate at interfaces between crystallites. This segregation can arise from incomplete deoxidation or chemical reactions during solidification.
Metallurgical relevance & risks during welding
Intergranular segregation leads to increased hot cracking susceptibility, as concentrated foreign atoms affect the hardness and stress tolerance of grain boundaries. It can also increase corrosion susceptibility by promoting chemical reactions at the segregates. This can lead to earlier deterioration of the metal.
Workshop practice & instructions
To avoid intergranular segregation, it is important to carry out careful deoxidation and keep melt time as short as possible. For high-quality steels, the use of shielding gases (such as argon) can also help keep foreign atoms away from the weld zone. Cooling should be controlled to ensure uniform solidification and minimal stresses.