Lack of Fusion Defects
Incomplete powder fusion happens when there's not enough heat input in neighboring passes or layers. This leaves unmelted particle clusters and mechanical weak spots in the part.
Physikalisch-chemischer Wirkmechanismus
Incomplete fusion of powder occurs when the thermal energy during the welding process is insufficient to fully fuse all metal particles. This can be caused by too short a heating time or too low a temperature.
Metallurgical Relevance & Welding Risks
Incomplete powder fusion results in unmelted particle clusters, which are mechanical weak points in the component. These can lead to cracks or fractures, especially under load. Additionally, loss of strength and density can occur.
Werkstattpraxis & Handlungsanweisungen
To avoid incomplete powder fusion, ensure sufficient heating time. This means the welding process should last long enough to fully fuse all metal particles. A guideline of 10-15 seconds per millimeter of part thickness is often recommended. Also, keep the temperature during welding above the melting point of the steel used to ensure complete fusion.