Solidification segregation
Solidification segregation is the uneven distribution of alloying elements in the structure during the liquid-to-solid phase transition, leading to local stresses and possible cracks.
Physical-Chemical Mechanism
During cooling of the weld metal, the metal solidifies. Alloying elements with different diffusion rates are not uniformly incorporated into the solid phase, leading to uneven segregation.
Metallurgical Relevance & Welding Risks
Solidification segregation can cause local stresses and cracks in the structure. These can be especially problematic in high-carbon steels or during uneven cooling, impacting the mechanical strength of the weld.
Workshop Practice & Instructions
To minimize solidification segregation, cooling should be controlled and uniform. Use suitable coolants or cooling methods such as quenching in air or water. Ensure adequate post-weld heat treatment (tempering) to relieve stresses.