Residual Gas Content Monitoring
Monitors residual gas content in the melt to avoid hydrogen embrittlement. High hydrogen content worsens mechanical properties and increases the risk of cracking.
Physicochemical mechanism of action
Residual gas content monitoring observes the balance between hydrogen, nitrogen, and oxygen in the melt. Too high a hydrogen content can lead to embrittlement, since hydrogen acts as a deoxidizer in the liquid state and binds oxygen.
Metallurgical relevance & risks in welding
A high hydrogen content in the melt can lead to deterioration of the mechanical properties of the joined steel. It increases susceptibility to cracking and coarsens the grain, which reduces toughness. This can lead to safety issues, especially in critical welding applications.
Workshop practice & instructions
To avoid hydrogen embrittlement, the residual gas content in the melt should be constantly monitored. A typical target range for hydrogen content is about 0.1 to 0.3 vol%. If hydrogen is excessive (e.g., above 0.5 vol%), measures such as increased outgassing or adjustment of the shielding gas mixture should be taken.