Columnar Crystalline Structure
Columnar structure forms due to directed heat extraction during casting and consists of long, parallel crystals. It has strong anisotropy of mechanical properties.
Physical-Chemical Mechanism of Action
The columnar crystalline structure forms when the liquid experiences directional heat removal during casting. This leads to the formation of long, parallel crystals aligned in a specific direction.
Metallurgical Relevance & Risks in Welding
The columnar crystalline structure exhibits strong anisotropy, meaning its mechanical properties (such as hardness and ductility) depend heavily on orientation. This can lead to uneven mechanical deformation and affect the service life of components. During welding, the structure can be altered by thermal stresses, which can lead to cracking or failure.
Workshop Practice & Action Instructions
To control the columnar crystalline structure and minimize its negative effects, it is important to precisely control the heat removal during casting. This can be achieved through special casting processes or the use of stabilizers. When welding, care must be taken to avoid strong thermal stresses, which can be ensured by careful selection of the welding process and post-weld heat treatment.