Micro-segregation
Microsegregation is the uneven distribution of alloying elements within a dendrite arm or grain during solidification, leading to different properties and risks.
Physical-Chemical Mechanism of Action
Segregation occurs when alloying elements are not distributed uniformly during cooling. This can be caused by unequal diffusion rates or thermal stresses.
Metallurgical Relevance & Welding Risks
Segregation leads to non-uniform distribution of properties such as hardness and toughness within the weld. This can cause localized cracks, wear spots, or increased susceptibility to fracture. It can also reduce resistance to chemical corrosion.
Workshop Practice & Action Guidelines
To minimize segregation, ensure uniform cooling of the weld. Use cooling water or special coolants. Set the cooling rate to stay within the critical temperature window for the desired microstructure. For heavy alloys, continuous cooling is required to avoid thermal stresses.