Phosphorus segregation tendency
Phosphorus segregation tendency: During cooling of austenite, phosphorus forms a segregation at grain boundaries, embrittling the structure and increasing crack susceptibility.
Physical-Chemical Mechanism of Action
During cooling of austenite, phosphorus reacts with surrounding metal atoms, forms a segregation, and enlarges at the grain boundaries. This leads to embrittlement of the structure.
Metallurgical Relevance & Risks in Welding
The tendency of phosphorus segregation increases the susceptibility to intercrystalline fractures and can lead to cracks and distortions. The structure becomes softer and less tough, which reduces mechanical strength.
Workshop Practice & Action Instructions
To minimize the tendency of phosphorus segregation, the weld pool should be well protected from external phosphorus sources. Controlled cooling is required during cooling to avoid embrittlement. If needed, use austenitic steel with lower phosphorus content.