Phosphorus as Impurity Element

Physikochemical mechanism of action

Phosphorus reacts with carbon in the melting zone and forms carbon phosphide. This compound enlarges the grain boundaries and makes the metal more susceptible to cold cracking.

Metallurgical relevance & risks in welding

A high phosphorus content leads to an increased number of cracks, especially after cooling. This can lead to component failure and a reduction in the service life of the weld joint.

Workshop practice & instructions

To minimize the risk of cold cracking, the phosphorus content in the steels used should be kept as low as possible. With high phosphorus content, careful control of the cooling process is required to reduce cold brittleness.