Phosphorus segregation bands
Phosphorus segregation lines are microscopic streaks in the rolled structure caused by uneven phosphorus distribution during solidification, leading to anisotropic mechanical properties.
Physicochemical Mechanism of Action
Phosphorus segregation bands form when phosphorus dissolves unevenly into the metal during rolling and condenses into microscopic streaks on solidification. These streaks affect the crystal structure and cause anisotropic mechanical properties, meaning the strength and hardness of the material differ in different directions.
Metallurgical Relevance & Welding Risks
The anisotropy of phosphorus segregation bands can lead to uneven mechanical properties, which poses risks for the strength and toughness of the rolled joint zone. If handled wrong during welding, these streaks can cause higher stress build-up and possible cracks or hot cracks.
Workshop Practice & Instructions
To minimize the negative effects of phosphorus segregation bands, keep a close eye on the rolling parameters and the welding process. That means holding optimal temperature and stress settings and using suitable welding methods to get even solidification and minimal stresses.