Areal slag inclusion
Area slag inclusion is process slag that spreads between weld layers and leads to cross-section reduction.
Physico-Chemical Mechanism of Action
Process slag forms during the welding process by crystallization of liquid metal. When this slag enters area-wise between the weld layers, it enlarges the cross-section reduction and can lead to mechanical strength losses.
Metallurgical Relevance & Welding Risks
An area slag inclusion can lead to a significant reduction in the effective cross-section of the weld. This increases the stress level and the risk of cracks or hot cracks. Moreover, the slag can act as a zinc site, leading to corrosion and further metal loss.
Workshop Practice & Work Instructions
To avoid area slag inclusion, it is important to carry out clean weld pool management. This includes regular removal of process slag and maintaining the correct melting temperature. For evaporation welding, the airflow should be optimized to minimize slag formation. For filler welding, careful preparation of the opening is required to lead the slag out of the opening.