Slag inclusion
Slag inclusion is the unintentional capturing of solidified melt mass in the weld metal, which reduces the effective cross-section and creates potential crack sites. These slag inclusions can result from inadequate cooling or improper preparation.
Physical-chemical action mechanism
Slag inclusion occurs when molten slag is not fully floated out during welding and gets trapped in the weld metal. This can be caused by too fast cooling or insufficient degassing of the weld pool.
Metallurgical relevance & welding risks
Slag inclusion reduces the effective weld cross-section and weakens the weld. This can lead to cracks, fractures, or distortion. Additionally, slag can contaminate the microstructure and impair the mechanical properties of the material.
Workshop practice & what to do
To avoid slag inclusion, careful preparation of the weld area is essential. Make sure the weld pool is fully degassed and no gas bubbles are trapped. If needed, use a proper welding technique or adjust the cooling rate to allow slag to float out.