Phosphorus Segregation Bands
Phosphorus segregation streaks are microscopic inhomogeneities in the structure, formed by line-type phosphorus enrichment during ingot or continuous casting solidification. They can lead to hardness and cracks.
Physicochemical Mechanism of Action
Phosphorus segregation streaks form when phosphorus gets enriched in bands during ingot or continuous-cast solidification. This leaves microscopic inhomogeneities in the metal structure.
Metallurgical Relevance & Welding Risks
These streaks can lead to hardening and cracking, especially when they end up inside the weld. The hardened zones can cut into the mechanical strength, while the cracks shorten the service life of the part.
Workshop Practice & Instructions
To keep phosphorus segregation streaks to a minimum, make sure cooling is controlled and the weld pool stays homogeneous. With heavy phosphorus contents you can slow down the cooling rate (e.g. t8/5 > 25 s) to keep the structure softer and avoid cracks.