Dendritic Segregation Rim
Dendrite segregation band is an area around dendrite axes where incomplete diffusion remains after solidification of the melt. This leads to chemical inhomogeneity and can cause cracks or failures.
Physical-Chemical Mechanism
Dendrite segregation band forms when, during solidification of the melt, certain chemical elements do not fully diffuse and concentrate at the dendrite axes. This leads to an uneven distribution of chemical components in the metal.
Metallurgical Relevance & Welding Risks
A high dendrite segregation band can lead to increased residual stress and cracks in the weld. The uneven chemical composition can also impair mechanical properties, such as strength and hardness. This can be problematic especially in high-performance steels or under high loads.
Workshop Practice & Action Items
To minimize dendrite segregation band, it is important to perform careful weld preparation. This includes proper cleaning and removal of contaminants. Additionally, the melting process should be controlled to allow for homogeneous diffusion. For critical applications, it may be helpful to use special welding processes or filler materials that influence the diffusion rate.