Nitrogen as Alloying and Impurity Element

Physical-Chemical Mechanism of Action

Nitrogen in dissolved form expands the metal lattice and prevents the movement of atoms. This increases strength and toughness as it reduces weak points and porosity.

Metallurgical Relevance & Welding Risks

Too high nitrogen content (above 0.1 %) can cause embrittlement of the weld. This makes the weld more prone to cracking and reduces its mechanical properties. Furthermore, embrittlement can reduce the service life of the component.

Workshop Practice & Action Guidelines

When welding steels with high nitrogen content, careful control of temperature and time is crucial. Use suitable shielding gas mixtures to control the nitrogen content in the weld zone. Too high gas flow can lead to embrittlement.