Nickel Superalloy Grain Boundary Segregation
Nickel superalloy grain boundary segregation refers to the enrichment of trace elements such as sulfur, phosphorus, or boron at grain boundaries. This increases the susceptibility to hot cracking during welding.
Physico-chemical mechanism of action
When manufacturing nickel superalloys, trace elements such as sulfur, phosphorus, or boron can concentrate at grain boundaries. This segregation affects the crystal structure and the mechanical properties of the material.
Metallurgical relevance & welding risks
The segregation of trace elements increases the susceptibility to hot cracking, as it contaminates the structure at grain boundaries. This can lead to fine cracks and deformation, especially if the material is not cooled properly.
Workshop practice & instructions
To minimize hot cracking, it is important to ensure controlled cooling after welding. Use a slow cooling blanket or cooling powder to regulate the temperature drop evenly. Make sure the weld is not cooled too quickly to maintain a homogeneous grain structure.