Phosphorus Segregation

Physical-Chemical Mechanism of Action

Phosphorus reacts with the metal in the melt, lowering the local melting temperature. This leads to a specific enrichment of phosphorus at the grain boundaries.

Metallurgical Relevance & Welding Risks

Lowering the melting temperature increases the likelihood of hot cracks because the metal in this region cools more slowly and hardens to glass-hard martensite. This can lead to cracks and distortion.

Workshop Practice & Action Guidelines

To minimize phosphorus segregation, set the melt temperature so it is above the critical point. Optimal melt time and controlled cooling are crucial. If needed, use metals with low phosphorus content.