Macroscopic Slag Inclusion
Macroscopic slag inclusion is visible non-metallic particles in the weld metal, often from not cleaning between passes. They can weaken the joint and cause cracks.
Physikalisch-chemischer Wirkmechanismus
Macroscopic slag inclusions form when incompletely cleaned interlayers during welding bind nonmetallic particles such as dust, paint, or contaminants with the metal. These particles remain in the weld and can become visible during cooling.
Metallurgical Relevance & Welding Risks
These slag inclusions can severely impair the mechanical properties of the weld. They lead to reduced strength and increase the risk of cracks and hot cracks. Moreover, they can contaminate the microstructure and reduce toughness.
Werkstattpraxis & Handlungsanweisungen
To avoid macroscopic slag inclusions, it is crucial to thoroughly clean interlayers. This can be achieved by removing dust, paint, and other contaminants. During welding, temperatures and times should be carefully controlled to ensure a homogeneous microstructure. If slag inclusions are suspected, the weld should be thoroughly inspected and, if necessary, re-welded.